Remote sensing observations provide an essential data contribution for operational meteorology, climate and environmental monitoring. They support public and private decision making and generate important socio-economic benefits. EUMETSAT is providing a European contribution to such operational services since more than 30 years. This talk will address the current and future geostationary Meteosat and polar EPS/Metop meteorological programmes, as well the optional programmes such as Jason and the third-party services with data and products from partners agencies. Finally, the contributions to the European Union’s Copernicus Programme will also be addressed.

The Joint Polar Satellite System 2 (JPSS-2) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is the third in a series (S-NPP VIIRS launched in October 2011 and JPSS-1 VIIRS in November 2017) of highly advanced polar-orbiting environmental satellites. JPSS-2 VIIRS underwent a comprehensive sensor-level Thermal Vacuum (TV) testing at the Raytheon's El Segundo facility in the summer of 2017. While the test program provided characterization for many spatial, spectral, and radiometric aspects of the VIIRS sensor performance, this paper focuses on the radiometric performance of the 14 reflective solar bands (RSB) that cover the wavelength range from 0.41 to 2.3 μm. Key calibration parameters, such as the instrument gain, signal- to-noise ratio (SNR), dynamic range and radiometric uniformity, were derived in TV environment for both the primary and redundant electronics at three instrument temperature plateaus: cold, nominal, and hot. This paper shows that all the JPSS-2 VIIRS RSB detectors have been well characterized, with the key performance metrics comparable to those in the prelaunch characterization of the previous two VIIRS instruments. Comparison of radiometric performance to sensor requirements as well as a summary of key sensor testing and performance issues will be presented.

In support of the prelaunch calibration of the Joint Polar Satellite System-1 (JPSS-1) Visible Infrared Imaging Radiometer Suite (VIIRS), the Bidirectional Reflectance Factor (BRF) and Bidirectional Reflectance Distribution Function (BRDF) of a VIIRS solar diffuser (SD) witness sample were determined using the table-top goniometer (TTG) located in the NASA GSFC Diffuser Calibration Laboratory (DCL). The BRF of the sample was measured for VIIRS bands in the reflected solar wavelength region from 410 nm to 2250 nm. The new TTG was developed to extend the laboratory’s BRF and BRDF measurement capability to wavelengths from 1600 to 2250 nm and specifically for the VIIRS M11 band centered at 2250 nm. We show the new features and capabilities of the new scatterometer and present the BRF and BRDF results for the incident/scatter test configuration of 0°/45° and for a set of angles representing of the VIIRS on-orbit solar diffuser calibration. The BRF and BRDF results of the SD witness were used to assist in finalizing the set of BRF values of J1 VIIRS SD to be used on-orbit. Comparison of the BRF results between the JPSS-1 VIIRS SD witness sample and the flight SD panel was made by varying different sample clocking orientations and by analyzing the ratio of BRF to total hemispherical reflectance in effort to minimize the uncertainty of the extrapolated flight BRF value at 2250 nm. Furthermore, differences between the prelaunch BRF results and those used in the VIIRS on-orbit BRF lookup table were examined to improve the VIIRS BRF calibration for future missions.

The Landsat-9 Operational Land Imager 2 (OLI-2) instrument, currently under development for launch in late 2020, is a clone of the Landsat-8 OLI instrument, which was launched in 2013. Ball Aerospace built and rigorously characterized the Landsat-8 OLI and is repeating the process for the Landsat-9 OLI-2. A major difference between the testing for OLI and OLI-2 will be spectral test equipment. The instrument-level spectral test for OLI made use of a double monochromator; the OLI-2 test will use of Goddard Laser for the Absolute Measurement of Radiance (GLAMR). The GLAMR system is a set of lasers, which collectively cover the entire spectral range of the OLI-2 spectral bands. The laser outputs are fed to a 30” integrating sphere via fiber optic cables, which OLI-2 can view from its position inside the thermal vacuum chamber. The laser-based spectral characterization offers several major advantages over the monochromator-based methods: (1) higher signal levels as compared to the lamp in the double monochromator providing better signal to noise and capabilities to measure out of band response, (2) full aperture illumination and flood illumination of multiple focal plane modules so that all detectors are tested and crosstalk effects can be observed, as opposed to the approximately 60 detectors illuminated by the slit image of the monochromator (3) an absolute spectral response characterization as opposed to relative spectral response. OLI-2 spectral testing with GLAMR should begin in late 2018. This work describes the spectral-radiometric test plan, test requirements, and GLAMR performance demonstrated prior to OLI-2 characterization.

The Thermal Infrared Sensor-2 (TIRS-2) aboard Landsat 9 will continue Landsat’s four decade-long legacy of providing moderate resolution thermal imagery from low earth orbit (at 705 km) for environmental applications. Like the Thermal Infrared Sensor aboard Landsat 8, it is a pushbroom sensor with a cross-track field of view of 15° and provides two spectral channels at 10.8 and 12 μm. To ensure radiometric, spatial, and spectral performance, a comprehensive pre-launch testing program is being conducted at NASA Goddard Space Flight Center at the component, subsystem, and instrument level. This paper will focus on the results from the subsystem level testing where the instrument is almost completely assembled. This phase of testing is specifically designed to assess imaging performance including focus and stray light rejection, but is also used to provide a preliminary assessments of spatial and spectral performance. The calibration ground support equipment provides a flexible blackbody illumination source and optics to conduct these tests. The spectral response test setup has its own illumination source outside the chamber that propagates through the calibration ground support equipment in an optical configuration designed for this purpose. This test configuration with the calibration ground support equipment and TIRS-2 subsystem in the thermal vacuum chamber enables a large range of illumination angles for stray light measurements. The results show that TIRS-2 performance is expected to meet all of its performance requirements with few waivers and deviations.

A KHz Pulsed Laser Detection System was developed employing the concept of charge integration with an electrometer, in the NASA Goddard Space Flight Center, Code 618 Calibration Lab for the purpose of using the pulsed lasers for radiometric calibration. Comparing with traditional trans-impedance (current-voltage conversion) detection systems, the prototype of this system consists of a UV-Enhanced Si detector head, a computer controlled shutter system and a synchronized electrometer. The preliminary characterization work employs light sources running in either CW or pulsed mode. We believe this system is able to overcome the saturation issue when a traditional trans-impedance detection system is used with the pulsed laser light source, especially with high peak-power pulsed lasers operating at kilohertz repetition rates (e.g. Ekspla laser or KHz OPO). The charge integration mechanism is also expected to improve the stability of measurements for a pulsed laser light source overcoming the issue of peak-to-peak stability. We will present the system characterizations including signal-to-noise ratio and uncertainty analysis and compare results against traditional trans-impedance detection systems.

The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) will measure the temperature of plants and use that information to better understand how much water plants need and how they respond to stress. The radiometer on-board the ECOSTRESS payload provides 5 TIR spectral bands with approximately 70m pixels and a nearly 400km swath. This radiometer has two on-board blackbodies to maintain calibration every sweep of the scan mirror (1.4s). The system has undergone an end-to-end test in a thermal-vacuum (TVAC) chamber showing excellent pre-flight radiometric results. This performance is in part enabled by a newly developed, high-speed, low noise, readout electronics. The readout electronics converts all 32-analog channels to digital for on-board processing and down link. Noise equivalent delta temperature (NEDT) measurements and brightness temperature (BT) retrievals are well within requirements. The optical modulation transfer function (OMTF) is also within specification.

Teledyne has a well-established heritage of supplying sensors for Earth observation space missions. Since early involvement in the SPOT satellites and Envisat, the French and UK Teledyne 2v sites have continued to develop sensors for Earth observation satellite suppliers and space agencies. For high-resolution imaging, panchromatic and multispectral TDI CCDs have been developed as the main sensors for the PLEIADES satellites and subsequent follow on Earth-imaging missions. The latest TDI CCD developed in combination with the ESA Enhanced CCD Design and Process ESCC Evaluation is presented, the CCD283-00 has 8μm anti-blooming pixels, multi-TDI stage integration time selection and multiple outputs for fast line advance time up to 5 kHz at 10 MHz pixel readout. The next generation of CMOS TDI sensors under design are described, with on-chip charge domain signal TDI combined with CMOS on-chip digital outputs. For Earth science, Teledyne e2v is a major contributor to the Copernicus Programme, successfully packaging and testing Sentinel-2 CMOS sensors and delivery of Sentinel-3 CCDs. For the recently launched Sentnel-5P TROPOMI hyperspectral imaging instrument, a custom CCD275 sensor was designed. Details are presented describing the improved radiation hardness, fast frame transfer design for up to 750ns per line and high UV and NIR quantum efficiency. For the next generation MTG and MetOp satellites, an overview is given of the Sentinel-4 UVN spectrometer, the Sentinel-5 UVNS and 3MI CCD sensors. Customised CMOS sensors specifically designed for space by Teledyne-e2v are in development for the MTG FCI and for MetOp. Details and progress are presented.

Recent major natural disasters highlighted the emergence of a new type of risk that manifests itself when the natural and technological worlds collide. The impact of a natural disaster on a facility storing or processing dangerous substances can result in the release of hazardous materials with possibly severe off-site consequences through toxic-release, fire or explosion scenarios. EU regulation, namely Directive 2012/18/EU, among its new elements explicitly requires the analysis of NaTech (natural hazard triggering technological disasters) hazards. Main issue related to NaTech accidents is the simultaneous occurrence of a natural disaster and a technological accident, both of which require simultaneous response efforts in a situation in which lifelines needed for disaster mitigation are likely to be unavailable. In addition, hazardous-materials releases may be triggered from single or multiple sources in one installation or at the same time from several hazardous installations in the natural disaster's impact area, requiring emergency-management resources occupied with responding to the natural disaster to be diverted. In this paper it is proposed and evaluated the application of multi-rotor systems for NaTech accident emergency management. The drone should be equipped with visible and near-infrared sensors, a thermal camera and dedicated sensors for the sensing and monitoring of dangerous substances. The multi-rotor systems allow stationary flight inside the industrial plants avoiding the presence of a human operator near hazardous-materials release source. The WiFi connection allows real time data processing and management of the situation. This methodology represent an effective approach to NaTech disasters management and consequences evaluation.

The Spectrometer Arduino Mega (SpAM) is a prism spectrometer that has been designed and fabricated by the Remote Sensing Group (RSG) at the College of Optical Sciences of the University of Arizona. SpAM is designed to be a low budget, stand alone, solar powered field spectrometer. RSG plans to use SpAM to measure the reflectance of natural surfaces in the field. After the laboratory calibration of SpAM, it will be deployed to the Radiometric Calibration Test Site (RadCaTS) at Railroad Valley, Nevada. A satellite uplink will allow RSG to upload SpAM measurements on a daily basis. SpAM measures and records the spectral composition of a light source or light reflected from a surface. The prism inside of SpAM refracts the input light onto a linear array of 512 silicon detectors. The detector-prism combination produces a spectral resolution of ~2 nm, and the overall spectral range is 433–760 nm. The spectral radiometric measurements produced by SpAM are stored and processed by an Arduino mega micro controller with network capabilities for field applications. SpAM will be used to analyze the spectral reflectance of Railroad Valley dry lake, and its accuracy and performance will be determined by a comparison with filter-based radiometers that have been produced by RSG. This work presents the design and instrumentation of SpAM, and an assessment of its ability to provide radiometric results for satellite calibration and other radiometric measurement applications.

Hawkeye is an ocean color instrument designed, manufactured and characterized at Cloudland Instruments, CA. It is a push broom instrument that has 8 spectral bands similar to SeaWiFS and a spatial resolution of 120 m. Each spectral band has 1800 detectors (pixels) and all 14,000 detectors (pixels) need to be calibrated independently. This paper describes the preliminary design of on-orbit calibration method to correct for the instrument response’s temperature sensitivity, scan angle dependency in radiometric sensitivity, relative spectral response (RSR), nonlinearity, and polarization sensitivity. We will provide a brief description on how each of the calibration parameters are used to address the instrument characteristics and how the calibration parameters are derived from instrument test data and use to retrieve ocean color products.

The GOES-16 Advanced Baseline Imager (ABI) is the first of four of NOAA's new generation of Earth imagers. The ABI uses large focal plane arrays (100s to 1000s of detectors per channel), which is a significant increase in the number of detectors per channel compared to the heritage GOES O-P imagers (2 to 8 detectors per channel). Due to the increase in number of detectors there is an increased risk of imaging striping in the L1b & L2+ products. To support post-launch striping risk mitigation strategies, customized ABI special scans (ABI North South Scans - NSS) were developed and implemented in the post-launch checkout validation plan. ABI NSS collections navigate each detector of a given channel over the same Earth target enabling the characterization of detector-level performance evaluation. These scans were used to collect data over several Earth targets to understand detector-to-detector uniformity as function of a broad set of targets. This effort will focus on the data analysis, from a limited set of NSS data (ABI Ch. 1), to demonstrate the fundamental methodology and ability to conduct post-launch detector-level performance characterization and advanced relative calibrations using such data. These collections and results provide critical insight in the development of striping risk mitigation strategies needed in the GOES-R era to ensure L1b data quality to the GOES user community.

The weather instrument of Advanced Baseline Imager (ABI) is the mission critical instrument on-board the GOES-16 satellite. Compared to the predecessor GOES Imager, GOES-16 ABI has many new advanced technical devices and algorithms to improve the data quality, including the double scan-mirror system. To validate the in-orbit response versus scan-angle (RVS), the Moon is used as a reference target for this purpose. During the post-launch test (PLT) and post-launch product test (PLPT) period, a series of special scans were conducted to chase and collect the lunar images at optimal phase angle range when it transited across the space within the ABI Field of Regard (FOR) from West to East. Analyses of the chasing events above and below the Earth indicated that the RVS variations at the East-West (EW) direction are generally less than 1% for all the six solar reflective bands. Same method is being applied to validate the GOES-17 ABI spatial uniformity for the visible and near-infrared (VNIR) bands.

GOES-16, the first new generation of NOAA’s geostationary satellite, was launched on November 19, 2016. The Advanced Baseline Imager (ABI) is the key payload of the mission. The instrument performance and satellite intercalibration results show that infrared (IR) radiances are well calibrated and very stable. Yet during its early post-launch tests (PLT) and post-launch product tests (PLPT) period, several calibration anomalies were identified with the IR bands: 1) the IR measurements of the Continental United States (CONUS) and mesoscale (MESO) images demonstrated an artificial periodicity of 15 minutes - Periodic Infrared Calibration Anomaly (PICA), in line with the Mode-3 timeline; and 2) the calibration coefficients displayed small discontinuities twice a day around satellite noon and midnight, which resulted in slight detectable diurnal calibration variations. This work is to report our investigation to the root causes of these anomalies, validation of the anomaly corrections, and assessment of the impacts of the corrections on the radiance quality. By examining the radiometrically calibrated space-swath radiance collected from the moon chasing events, it was found that these anomalies were attributed to the residuals of the spatial uniformity corrections for the scan mirrors. A new set of scan mirror emissivity correction Look-Up Tables (LUTs) were later delivered by the Vendor and implemented operationally. Further analyses showed that the new emissivity LUTs significantly reduced the periodic radiometric variation and diurnal variations. The same method will be applied to validate the IR spatial uniformity for the future GOES-R series ABI instruments.

The US Geostationary Operational Environmental Satellite – R Series (GOES-R) was launched on November 19, 2016 and was designated GOES-16 upon reaching geostationary orbit ten days later. After checkout and calibration, GOES-16 was relocated to its operational location of 75.2 degrees west and officially became GOES East on December 18, 2017. The Advanced Baseline Imager (ABI) is the primary instrument on the GOES-R series for imaging Earth’s surface and atmosphere to significantly improve the detection and observation of severe environmental phenomena. A team supporting the GOES-R Flight Project at NASA’s Goddard Space Flight Center developed algorithms and software for independent verification of ABI Image Navigation and Registration (INR), which became known as the INR Performance Assessment Tool Set (IPATS). In this paper, we will briefly describe IPATS on top concept level, and then introduce the Landsat chips, chip registration algorithms, and how IPATS measurements are filtered. We present GOES-16 navigation (NAV) errors from flight data from January 2017 to May 2018. The results show a) IPATS characterized INR variations throughout the post-launch test phase; and b) ABI INR has improved over time as post-launch tests were performed and corrections applied. Finally, we will describe how estimated NAV errors have been used to assess and understand satellite attitude anomalies and scale errors etc. This paper shows that IPATS is an effective tool for assessing and improving GOES-16 ABI INR and is also useful for INR long-term monitoring.

A primary objective of the GOES-16 post-launch airborne science field campaign was to provide an independent validation of the SI traceability of the Advanced Baseline Imager (ABI) spectral radiance observations for all detectors post-launch. The GOES-16 field campaign conducted sixteen validation missions (March to May 2017), three of which served as the primary ABI validation missions and are the focus of this work. These validation missions were conducted over ideal Earth targets with an integrated set of well characterized hyperspectral reference sensors aboard a high-altitude NASA ER-2 aircraft. These missions required ABI special collections (to scan all detectors over the earth targets), unique aircraft maneuvers, coordinated ground validation teams, and a diplomatic flight clearance with the Mexican Government. This effort presents a detector-level deep-dive analysis of data from the targeted sites using novel geospatial database and image abstraction techniques to select and process matching pixels between ABI and reference instruments. The ABI reflective solar band performance (ABI bands 1-3 & 5-6) was found to have biases within 5 % radiance for all bands, except band 2; and the ABI thermal emissive band performance was found to have biases within 1 K for all bands. Additional inter-comparison results using targeted ABI special collections with the Low Earth Orbit reference sensor S-NPP/VIIRS will also be discussed. The reference data collected from the campaign has demonstrated that the ABI SI traceability has been validated post-launch and established a new performance benchmark for NOAA’s next generation geostationary Earth observing instrument products.

The Advanced Baseline Imager (ABI) is a critical instrument onboard GOES-16 which provides high quality Reflective Solar Bands (RSB) data though radiometric calibration using onboard solar diffuser. Intensive field campaign for post-launch validation of the ABI L1B spectral radiance observations was carried out during March-May, 2017 to ensure the SI traceability of ABI. In this paper, radiometric calibrations of the five RSBs of ABI are evaluated with the measurements by Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) onboard the high-altitude aircraft ER2. The ABI MESO data processed by the vendor with ray-matching to AVIRIS-NG during the field campaign was compared with the AVIRIS-NG measurements for radiometric bias evaluation. Furthermore, there were several implementations and updates in the solar calibration of ABI RSBs which resulted in different versions of detector gains and nonlinear calibration factors. These calibrations included the calibration by the operational ground processing system, by vendor and the calibration with updated nonlinear calibration factor table for striping mitigation and accounting for the integration time difference between solar calibration and Earth view. The North-South Scan (NSS) field campaign data of ABI were re-processed with these calibration coefficients to quantitatively evaluate the detector uniformity change. The detector uniformity difference are traced back to the difference in the implementation of the solar calibration.

As part of the geolocation accuracy assessment of lightning flashes detected by the Geostationary Lightning Mapper (GLM) on the GOES-16 and GOES-17 satellites (Geostationary Operational Environmental Satellite), two satellite laser ranging stations employed laser beacon systems to generate transient light pulses that simulate natural lightning around 777.4 nm to validate the pre-launch spec of 5 km. The pulse width, repetition rate, wavelength, and power of the laser-pulses were configured to produce sufficient instrument response to be detected as synthetic lightning events by the GLM instrument. During the testing period from April 2017 to January 2018, the laser systems illuminated the GOES-16 satellite to observe diurnal variation of the GLM system response, with particular emphasis on geolocation accuracy. The final GOES-16 laser beacon tests, which used the latest updates of the geolocation algorithms implemented by the GOES-R Ground Segment, showed the offsets between the GLM geolocated location and the known laser locations were within 5 km.

EUMETSAT is providing space observations for operational meteorology and climate monitoring, operating geostationary and sun-synchronous polar orbiting satellites through mandatory programmes. Optional programmes provide complementary observations for altimetry and oceanography. Data and products from partner agencies’ satellites are made available by to the user community through EUMETSAT third party programmes. EUMETSAT’s current fleet of operational geostationary spacecraft comprises the four satellites of the Second Generation of Meteosat (MSG), Meteosat-8, Meteosat-9, Meteosat-10 and Meteosat-11. Meteosat-11 was being taken out of in orbit storage and become the prime satellite in early 2018. Meteosat-8 continues to contribute to the IODC service. The EUMETSAT Polar System (EPS) provides data from sun-synchronous polar orbit with currently two satellites: Metop-B, launched in September 2012 and currently the prime satellite, and Metop-A, the first of the series, in orbit since October 2006. The third of the series of three satellites, Metop-C is planned to be launched in November 2018. These satellites are part of the Initial Joint Polar System (IJPS) together with the US. EUMETSAT’s first optional programme continues to provide data from the Jason-2 and Jason-3 satellites. To assure continuity in the mandatory missions the development of Meteosat Third Generation (MTG) is ongoing. The EPS-SG (EPS Second generation) programme is also under full development. In the frame of the Copernicus Programme EUMETSAT operates the Sentinel-3A satellite and provides operational marine products. Sentinel-3B, a second satellite, was launched in April 2018 and is currently under commissioning.

The 3MI instrument is one of the missions of the EPS-SG program to be launched in 2021. This polarimetric mission is a heritage of the POLDER mission, with improved capabilities and now placed in a fully operational long- term framework. The spectral range was extended from the visible-near-infrared (410 to 910nm) to the shortwave- infrared domain (up to 2200nm). The spatial resolution (4km at nadir) and the swath (2200×2200km²) were also improved compared to previous POLDER instruments. The 3MI concept of the multi-viewing, multi-spectral and multi- polarized Imaging will be described, especially how these 3 information are acquired together with one instrumental concept that remains simple. The performance necessary to meet the mission requirements will be initially reached before launch through a fully dedicated ground campaign and maintained once in orbit through an extensive vicarious calibration strategy. The level 1 products available to the users will be geolocated Stokes vectors on the native geometry (Level 1B) and geoprojected multi-directional and spectral Stokes vectors (Level 1C). Level-2 products will provide geophysical and microphysical parameters for aerosol and clouds. The presentation will detail the 3MI concept, overview the mission characteristics, and browse the foreseen ground campaign and in-flight strategy necessary to reach the performance, as well as the products available to the users.

As a space agency in Taiwan, NSPO is used to design satellites with good heritage of space-graded parts and components to reduce program risks. However, the local industrial companies were hard to get the chance to join the space programs in the past decades because they were not qualified vendors in the beginning. Taiwan’s government would like NSPO to actively promote local space industry recently, so we try a different approach for the new remote sensing satellite program. The first step is to identify key components and core technologies that will be used in the future space program. The second step is to survey local companies and research institutes to find the potential partners for developing space products. The third step is to derive specifications and verification plan for those components that we want to develop. If the developed components can pass the qualification tests, they will be used in the new remote sensing satellite program. We try to minimize the hardware cost with COTS (Commercial off-the-shelf) approach, so the overall cost of each satellite can be reduced. The new satellite platform will be treated as flight demonstration platform for the future mission satellites due to its low cost. Any new components or new technologies will be verified with this platform. There are more than fifteen key components and technologies will be developed and verified. The latest development status are described in this paper.

The Atmospheric Infrared Sounder (AIRS) radiometric calibration coefficients convert the counts measured from the instruments A/D converters (Level 1A) to SI traceable radiance units (Level 1B). The calibration equations are based on how the instrument operates and follow a simple second order relationship between counts and radiance. Terms are included to account for nonlinearity of the detectors, emissivity and temperature knowledge of the on-board calibrator (OBC) blackbody and radiometric offset due to coupling of the polarization of the scan mirror with the spectrometer. In this paper, we re-derive the radiometric calibration equation with a little more rigor and account for the view angle of each of the 4 space views. We then derive new polarization coefficients from the 4 space views over the mission and use them re-derive the coefficients for blackbody emissivity and nonlinearity. We then compare new coefficients (Version 7k) with the latest operational version of the AIRS radiometric calibration coefficients (Version 5). The AIRS Version 5 coefficients were sufficiently adequate that an update has never been made since AIRS launch in 2002. However, it can be seen, when we compare to the Cross-track Infrared Sounder (CrIS), that better agreement is made in Version 7. The impact of the new coefficients is highest at cold scene temperatures and very warm temperatures.

With global warming at the rate of 10 mK/yr, it is important to carefully characterize instrument related trends, if the AIRS data are used for climate change research. We evaluated the stability of the AIRS Level 1B version 5 calibration for seven atmospheric window channels between 2002 and 2018 under clear ocean clear conditions. We do this by analyzing the trend in the difference between the observed brightness temperatures and those calculated based on the daily Sea Surface Temperature product provided by NOAA. Trends for the 961, 1128 and 1231 cm^-1 channels are close to +3 mK/yr, at 790 and 901 cm^-1 the trends are 6 mK/yr. For all observation the AIRS window channels read increasingly warmer. The observed trends are day/night consistent and insensitive to changes in the clear filter. The effects of scattering due to scan mirror contamination are evident at 2508 and 2616 cm^-1 for extremely cold scenes surrounded by warm scenes, but scattering does not produces the observed warming trends for warm scenes. It is possible that much of the observed warming in the AIRS window channels is due to a shift in the day/night and skin effect corrections, which was not accounted for in our analysis. This would be a new geophysical effect related to the warming of the oceans, which requires more careful evaluation.

There are now five hyperspectral infrared sounders in orbit (AIRS, two CrIS instruments, two IASI instruments). A long-term record spanning these instruments and continuing forward with future instruments holds great promise for the study of weather and climate. This long-term record must separate the effects of instrument artifacts and weather variability. We introduce the “StratRad” stratified radiance means product, containing means of groups of spectra for AIRS on Aqua and CrIS on SNPP. We show how this product can be used both to illuminate instrument artifacts and to study common observations of weather patterns at an accuracy of better than 0.1 K. Radiances are stratified by latitude, longitude, day/night, land/sea, and observation angle.

The Clouds and Earth Radiant Energy System (CERES) program has the objective of producing a multi-decadal Climate Data Record (CDR) of Earth Radiation Budget (ERB) measurements. CERES Flight Model 6 was placed in orbit in November 2017 aboard the NOAA-20 spacecraft. FM-6 joined the FM-1 and FM-2 aboard the Terra, FM-3 and -4 aboard the Aqua, and FM-5 aboard the S-NPP spacecraft to seamlessly continue the Earth radiation budget CDR. FM-6 is the most highly calibrated CERES instrument due to improvements in the extensive pre-launch ground calibration campaign. Operations in orbit began with functional check-outs followed immediately by a period of intensive calibrations and validation checks and then transition to the long-term Cal/Val protocol. Initial results demonstrate agreement with ground calibrations within 0.5%. Operations to inter-calibrate with other CERES instruments will commence in the Spring of 2018. The current effort will document the results of the intensive post launch cal/val campaign completed in early 2018 as well as continued radiometric performance and including intercomparisons with other CERES instruments already on orbit.

The Clouds and the Earth’s Radiant Energy System (CERES) scanning radiometer is designed to measure the solar radiation reflected by the Earth and thermal radiation emitted by the Earth. Five CERES instruments are already in service; two aboard the Terra spacecraft, launched in 1999; two aboard the Aqua spacecraft, launched in 2002, and one aboard the S-NPP spacecraft launched in 2011. A sixth instrument, flight model 6 (FM6), launched in November 2017 aboard the JPSS-1 satellite, began taking radiance measurements on January 6th, 2018. The CERES FM6 instrument uses three scanning thermistor bolometers to make broadband radiance measurements in the shortwave, total, and longwave regions. An internal calibration module (ICM) used for in-flight calibration is built into the CERES instrument package consisting of an anodized aluminum blackbody source for calibrating the total and longwave sensors, and a shortwave internal calibration source (SWICS) for the shortwave sensor. The calibration sources are used to define shifts or drifts in the sensor response over the life of the mission. Additional validation tests including solar calibrations and coastline detections are used to validate the pointing accuracy of the instrument and supplement the ICM data. This paper presents the results of FM6 on-orbit internal calibrations, discusses any ground to flight changes, describes trends in the calibration data, summarizes the results of the solar calibration and coastline detection analysis, and discusses strategies for comparing FM6 to other CERES instruments.

Earth Radiation Budget (ERB) instruments that are used to measure the incoming solar and outgoing longwave radiation have been a crucial part of studying the Earth's radiation balance. Over the years, the science community has made considerable advancements in making these measurements more accurate with the help of modeling tools that allow for on-ground parametric analysis. Therefore, in order to understand and characterize the instrument’s complex design, NASA Langley Research Center has partnered up with the Thermal Radiation Group of Virginia Tech to develop a complete end-to-end modeling tool that aims to enhance the interpretation of an Earth radiation budget-like instrument on orbit. This is a complete end-to-end, first-principle, dynamic, electro-thermal numerical model for a generic scanning radiometer that starts with photons arriving at the entrance aperture of the instrument to reading the data out as digital counts. This modeling tool accounts for the different subcomponents of the instrument, such as on-board calibration targets, optical module, detector elements, and signal conditioning electronics. This end-to-end model will help understand the science data stream output and help the science and the engineering community in quantifying any anomalous effects and uncertainties that arise from unknown knowledge of system parameters.

Radiation Budget Instrument (RBI) is a scanning radiometer that measures earth reflected solar radiance and thermal emission at the top-of-atmosphere. RBI has three radiance channels that cover 0.25-5μm, 5-100μm and 0.25-100μm spectral bands respectively. To ensure highly accurate measurement throughout mission life, RBI is equipped with two internal calibration targets to routinely calibrate the radiance channels on orbit. A highly stable Electrical Substitution Radiometer (ESR) based Visible Calibration Target (VCT) is used to calibrate RBI short wave and total channel; A 3- bounce specular trap blackbody Infrared Calibration Target (ICT) with high emissivity, High accuracy temperature measurement is used to calibrate the RBI long wave channel. Prior to launch, RBI will undergo a comprehensive ground calibration campaign in a thermal vacuum chamber developed for RBI at the Space Dynamics Laboratory (SDL). A set of calibration targets developed by SDL, including short wave radiance source (SWRS), long wave infrared calibration source (LWIRCS), and a space view simulator (SVS) were used for RBI ground calibration. The plan is to characterize RBI absolute radiance measurement accuracy and repeatability, tie internal calibration targets to ground calibration, to carry the ground calibration to orbit. In fall 2017, the RBI Engineering Development Unit (EDU) went through the ground calibration campaign, as the pathfinder for flight unit. A large discrepancy was observed between the SDL target based calibration and RBI internal target based calibration. In this paper, we describe the discrepancy observed, the root cause analysis, and some lessons learned.

The NOAA-20 Visible Infrared Imager Radiometer Suite (VIIRS) was launched on November 18, 2017. VIIRS has been scheduled to view the Moon approximately monthly with a spacecraft roll maneuver after its NADIR door open on December 13, 2017. To reduce the uncertainty of the radiometric calibration due to the view geometry, the lunar phase angles of the scheduled lunar observations are confined in the range from -51.5° to -50.5°, which is same as the range used for SNPP VIIRS lunar calibration and where the negative sign for the phase angles indicates that the VIIRS views a waxing moon. Different from the MODIS lunar observations but same as those of SNPP VIIRS, the scheduled VIIRS lunar observations occur on the day side of the Earth. The lunar observations can be used to identify inoperable detectors. They can be used to check if there are crosstalk contaminations among the instrument’s bands and to track on-orbit changes in the Reflective Solar Bands (RSB) detector gains. In this paper, we report our results using the lunar observations to identify inoperable detectors, to examine the on-orbit crosstalk effects among NOAA-20 VIIRS bands, to track the VIIRS RSB gain changes in first few months on-orbit, and to compare the gain changes derived from lunar and SD/SDSM calibration.

Two MODIS instruments (Terra and Aqua) and two VIIRS instruments (S-NPP and JPSS-1) are currently operated in space, continuously making global earth observations in the spectral range from visible (VIS) to long-wave infrared (LWIR). These observations have enabled a broad range of environmental data records to be generated and distributed in support of both operational and scientific community. Despite extensive pre-launch calibration and characterization performed for both MODIS and VIIRS instruments and routine on-orbit calibration activities carried out using their onboard calibrators (OBC), various spacecraft maneuvers have also been designed and implemented to further enhance the sensor on-orbit calibration and data quality. This paper focuses on the use of observations made during spacecraft pitch maneuvers of MODIS and VIIRS in support of their on-orbit characterization of thermal emissive bands (TEB) response versus scan-angle (RVS). In the case of Terra MODIS, lunar observations made from instrument nadir view during spacecraft pitch maneuvers are used to compare with that made regularly through instrument space view (SV) port to evaluate on-orbit changes in RVS and band-to-band registration (BBR) for the reflective solar bands (RSB). In addition to results derived from spacecraft pitch maneuvers performed for MODIS and VIIRS, discussion is provided on the advantages, challenges, and lessons for future considerations and improvements.

The radiometric performance of the reflective solar bands (RSBs) of NOAA-20 VIIRS, recently launched on 18 November 2017, is evaluated through an intercomparison with Aqua MODIS. The analysis adapts a “nadir-only” refinement of the simultaneous nadir overpass (SNO) to generate comparison time series for assessment of the on-orbit calibration of NOAA-20 VIIRS RSBs using the official sensor data records (SDRs). The comparison result reveals an unstable and varying early radiometric performance upward of 5%. SNPP VIIRS, the precursor VIIRS, is also used to generate a comparison time series against Aqua MODIS. The result shows that NOAA-20 VIIRS RSBs have a 2 to 8% radiometric deficit relative to SNPP VIIRS RSBs.

Near-nadir observations of the Libya 4 site from the S-NPP VIIRS Day-Night Band (DNB) and Moderate resolution Bands (M bands) are used to assess the detector calibration stability and half-angle mirror (HAM) side differences. Almost seven years of Sensor Data Records products are extracted from the Libya 4 site center over an area of 32×32 pixels. The mean values of the radiance from individual detectors per HAM side are computed separately. The comparison of the normalized radiance between detectors indicates that the detector calibration differences are wavelength dependent and the differences have been slowly increasing with time for short wavelength bands, especially for M1-M4. The maximum annual average differences between DNB detectors are 0.77% in 2017 at HAM-A. For the M bands, the maximum detector differences in 2017 are 1.7% for M1, 1.8% for M2, 1.3% for M3, 1.2% for M4, 0.67% for M5, 0.75% for M7, 0.57% for M8, 13% for M9, 0.63% for M10, and 0.66% for M11. The average HAM side A to B difference in 2017 are 0.00% for DNB, 0.22% for M1, 0.17% for M2, 0.15% for M3, 0.09% for M4, -0.07% for M5, 0.02% for M7, 0.01% for M8, 1.4% for M9, 0.01% for M10, and 0.03% for M11. Results for M6 are not available due to the signal saturation and M9 results are not accurate because of the low reflectance from the desert site and the strong atmospheric absorption in this channel. The results in this study help scientists better understand each detector’s performance and HAM side characteristics. Additionally, they provide evidence and motivation for future VIIRS calibration improvements.

Accurate radiometric cross calibration is critical for guaranteeing the consistency of measurements from different Earth observation sensors, and fully using the combined data in quantitative applications. It becomes even more indispensable with the rapid increase of remote sensing data availability from numerous sensors. The assessment of the Spectral Band Adjustment Factor (SBAF) is a key component of the cross-calibration method. The SBAF compensates for intrinsic differences in sensor response caused by Spectral Response Function (SRF) mismatches. Currently, Sentinel and Landsat data represent the most widely accessible medium spatial resolution multispectral satellite data. Hence, in this study, the SBAF of the Multi-Spectral Imager (MSI) on-board Sentinel-2 and the Operational Land Imager (OLI) on-board Landsat-8 was estimated over pseudo-invariant calibration sites (PICS) located in North Africa. The SBAF depends on the hyperspectral profile of the target and the sensor SRF. Here, the hyperspectral profile was derived from the Hyperion hyperspectral imager on-board the EO-1. Finally, it is important to highlight that an estimate of the SBAF is incomplete unless accompanied with its uncertainty. The uncertainty analysis of the SBAF was implemented using Monte Carlo simulation. The results obtained in this study can be utilized by any user who needs the SBAF of the OLI and MS1 over North Africa Desert sites.

The Radiometric Calibration Test Site (RadCaTS) is a suite of commercial and custom instruments used to make measurements of the surface reflectance and atmosphere throughout the day at Railroad Valley, Nevada. It was developed in response to the need for daily radiometric calibration data for the vast array of Earth-observing sensors on orbit, which is continuously increasing as more nations and private companies launch individual environmental satellites as well as large constellations. The current suite of instruments at RadCaTS includes five ground-viewing radiometers (GVRs), four of which view the surface in a nadir-viewing configuration. Many sensors such as those on Landsat-7 and Landsat-8 view Railroad Valley within 3° of nadir, while others such as those on Sentinel-2A and -2B, RapidEye, Aqua, Suomi NPP, and Terra can view Railroad Valley at off-nadir angles. Past efforts have shown that the surface bidirectional reflectance distribution function (BRDF) has minimal impact on vicarious calibration uncertainties for views <10°, but the desire to use larger view angles has prompted the effort to develop a BRDF correction for data from RadCaTS. The current work investigates the application of Railroad Valley BRDF data derived from a BRF camera developed at the University of Arizona in the 1990s (but is no longer in use) to the current RadCaTS surface reflectance measurements. Also investigated are early results from directional reflectance studies using a mobile spectro-goniometer system during a round-robin field campaign in 2018. This work describes the preliminary results, the effects on current measurements, and the approach for future measurements.

Optical and electronic cross-talk effects are present in the Terra MODIS sensor. Those effects are reviewed and the physical (engineering) characteristics that give rise to the effects are described when they are known. The potential for performance degradation also is assessed for each effect. The long-term consequence of these effects is to give rise to Terra MODIS to Aqua MODIS performance trend differences and researchers are cautioned to use care in interpretation of these trend differences as potential diurnal environmental effects.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on board the Terra and Aqua space- craft are equipped with several on-board calibrators (OBCs) and continue to operate normally since launch. One such calibrator is the Spectro-Radiometric Calibration Assembly (SRCA), whose regular calibrations provide accurate measurements in radiometric, spatial and spectral modes. The SRCA is able to monitor and measure the center wavelength (CW) shift, the bandwidth (BW) shift and a major portion of the relative spectral response (RSR) for each of the MODIS reflective solar bands (RSBs) while operating in spectral mode. However, there are several factors that influence the uncertainties when calculating these results. This paper provides a brief overview of the SRCA in spectral mode, along with how the CWs, BWs and RSRs of the MODIS RSBs are calculated. The operational factors that contribute to the spectral uncertainty are also discussed, including the variation of the half-included angle (β) and the grating motor offset angle (θ_off ) of the monochromator. A comparison between the theoretical and on-board CW uncertainty is also provided.

Calibration of the on-orbit gain changes of the narrow bandwidth reflective solar bands (RSB) of Terra and Aqua MODIS is usually based on the band center wavelength. The relative spectral response (RSR) of each band is assumed to be constant on orbit and the time dependence of an overall gain factor is calculated. Any on-orbit changes to the RSR of the MODIS bands will introduce some error into the calibration and may also have an impact on the Earth scene radiance retrieval. We consider two different ways to track how the RSR of the MODIS RSB may be changing on orbit, and the effect that these changes will have on the calibration. First, we examine in-band RSR measurements from the spectro-radiometric calibration assembly (SRCA) carried on-board both MODIS instruments. Second, we study the broadband degradation of the MODIS scan mirror and how it may be changing the effective out-of-band response of the RSB. We find that RSR changes have a small effect on the radiance calibrated using the on-board solar diffuser, generally less than 0.5% in all cases at any time in the missions, with bands 1, 8, and 9 impacted the most.

This study presents a modeling approach to improve solar diffuser (SD) degradation determination from SD stability monitor (SDSM) measurements. The MODIS instrument uses a SD to calibrate its reflective solar bands (RSBs) on-orbit. Due to the imperfectly designed SDSM sun view screen, the SD reflectance tracked by SDSM has large noise. The SDSM measurements noise is spectrally coherent and can be minimized by normalizing measurements to the least degraded detector 9 (936 nm). In this study, a SD degradation model is used to determine the SD degradation’s wavelength dependency and the detector 9 degradation is estimated by the model solution. The results show the SD degradations measured at 6 SDSM detectors (554 - 936 nm) have stable relationships, where the degradation is inversely proportion to 1/wavelength^4. The model estimated SD degradation at SDSM detector 9 wavelength (936 nm) is ~0.9% from 2002 to 2018. Based on the SD degradation model solution, the SD degradation at short/mid wave bands are estimated to improve short/mid wave bands calibration. The model can also be used to improve interpolating SD degradation at SDSM detectors to RSB wavelengths. Compared to linear interpolation, bands 9 and 10 show the largest differences of up to 0.3 and 0.4% respectively. These differences directly impact the calibration coefficients of these bands.

Development of remote monitoring systems (RMS) demands the decision of some problems of the organisation of data flows of measurements. These systems the important place is occupied with the systems focused on studying of marine systems. The technique of detection offered in given work and identification of the abnormal phenomena in the marine environment (microwave and optical) combines presence with application of possibilities of remote measurements algorithmic and the software, allowing to solve measurement and detection problems in real time. The effective decision of these problems is impossible without wide introduction in practice of researches of the automated systems of gathering, storage and data processing on the basis of modern computer systems with application of technology of open systems In this paper presented, a remote monitoring system for detecting anomalies on the sea surface is considered. Estimates of the effectiveness of a multichannel solver are obtained. As an informative sign of waiting for the detection of anomalies on the sea surface, a model of the "spotting" of the surveyed surface was developed on the basis of empirical data. Also estimates were obtained of the feasibility of the fixing block RMS in the case of mobile anomalies The experimental verification of the effectiveness of the algorithms considered is based on data from the "Intercosmos-21" satellite for the Pacific regions.

Change detection techniques for remote sensing images are increasingly applied to many fields, such as disaster monitoring, vegetation coverage analysis and so on. With the increase of image spatial resolution, noises and details increased significantly, compared with the low-resolution image. How to improve the accuracy of change detection for high resolution image has been a critical topic. In this paper, a new method for high resolution image change detection based on pyramid mean shift smoothness and morphology is proposed. Firstly, the difference image is generated by fusing the difference feature and log difference feature based on stationary wavelet transform. Secondly, two-layer pyramid mean shift smoothness algorithm is applied to highlight the objects that may be changed and to eliminate interference regions, meanwhile, to retain the obviously different features. Thirdly, in order to enhance the contrast between the change objects and unchanged regions, the improved frequency-tuned saliency detection strategy is utilized to further enhance the change objects. Lastly, change objects are extracted by the fuzzy local C-means cluster algorithm and the final change map is generated by morphological operation. The method has been tested on four-temporal datasets, meanwhile, compared with other typical methods.

Hyperspectral imaging has been widely applied in many fields due to the advantage of high spectral resolution. However, consisting of acquisition, transmission, reception and display, a hyperspectral imaging system may be disturbed in each part and thus leads to degradations that limit the precision of subsequent processing. It is therefore an important preprocessing step to remove the noise of acquired image data as much as possible. In this paper, we propose a novel regularization method for hyperspectral image denoising. Firstly, the low-rank and sparsity constraints are jointly used to establish the regularization model. For each spectral band, the low-rank constraint is for exploiting inter-column/- row correlations, while the sparsity constraint aims to exploit intra-column correlations. Secondly, reweighed ℓ¹ norm strategy, which solves a sequence of weighted norm optimization problems and updates the weights with the solution ℓ₁ of the last iteration, is introduced to approximate norm to achieve improved priori performance of the two ℓ₀ constraints. Lastly, we apply the alternating direction method (ADM) under the augmented Lagrangian multiplier (ALM) framework to solve the model efficiently. Both low-rank and sparsity priors are reweighted at each iteration to promote low-rankness and sparseness of the solution. The denoising effect of our method is tested on real hyperspectral image data with different noise level. The experiments demonstrate the practicality of our proposed method.

With close to 40 years of satellite observations, from which, cloud, land-use, and aerosol parameters can be measured, inter-consistent calibrations are needed to normalize retrievals across satellite records. Various visible-sensor inter-calibration techniques have been developed that utilize radiometrically stable Earth targets, e.g., deep convective clouds and desert/polar ice pseudo-invariant calibration sites. Other equally effective, direct techniques for intercalibration between satellite imagers are simultaneous nadir overpass comparisons and ray-matched radiance pairs. Combining independent calibration results from such varied techniques yields robust calibration coefficients, and is a form of self-validation. One potential source of significant error when cross-calibrating satellite sensors, however, are the often small but substantial spectral discrepancies between comparable bands, which must be accounted for. As such, visible calibration methods rely on a Spectral Band Adjustment Factor (SBAF) to account for the spectral-responsefunction-induced radiance differences between analogous imagers. The SBAF is unique to each calibration method as it is a function of the Earth-reflected spectra. In recent years, NASA Langley pioneered the use of SCIAMACHY-, GOME-2-, and Hyperion-retrieved Earth spectra to compute SBAFs. By carefully selecting hyperspectral footprints that best represent the conditions inherent to an inter-calibration technique, the uncertainty in the SBAF is greatly reduced. NASA Langley initially provided the Global Space-based Inter-calibration System processing and research centers with online SBAF tools, with which users select conditions to best match their calibration criteria. This article highlights expanded SBAF tool capabilities for visible wavelengths, with emphasis on spectral range filtering for the purpose of separating scene conditions for the channel that the SBAF is needed based on the reflectance values of other bands. In other words, spectral filtering will enable better scene-type selection for bands where scene determination is difficult without information from other channels, which should prove valuable to users in the calibration community.

Molecular collisions are manifested as a perturbation of the shapes of molecular optical resonances. Therefore, on the one hand, the line-shape analysis of accurate molecular spectra constitutes an important tool for studying quantum scattering and testing ab initio molecular interactions [1]. On the other hand, the collisional effects can deteriorate the accuracy of atmospheric measurements of the Earth and other planets, modify the opacity of the exoplanetary atmospheres as well as influence the accuracy in optical metrology based on molecular spectroscopy [2,3]. Recently a new relational structure has been introduced to the most extensively-used line-by-line spectroscopic database HITRAN [4,5], enabling the collisional, beyond-Voigt line-shape effects to be represented. It is, however, extremely challenging to populate the entire database with purely experimental parameters for all the molecular transitions and thermodynamical conditions (all the bands, branches and temperature ranges). We demonstrate a new methodology of generating a comprehensive dataset of the beyond-Voigt line-shape parameters from fully ab initio quantum-scattering calculations. We also demonstrate first such a complete dataset for the benchmark system of helium-perturbed H2 line. We provide the temperature dependences for the pressure broadening and shift parameters, as well as for the Dicke parameter using generalized spectroscopic cross sections resulting from quantum scattering calculations on accurate ab initio potential energy surfaces. The results are consistent with the recently adapted HITRAN parameterisation of the Hartmann-Tran profile [4]. The calculations and methodology are also validated on the ultra-accurate experimental data of the H2-He system. References [1] Wcisło P et al. 2015 Phys. Rev. A 91, 052505. [2] Moretti L et al. 2013 Phys. Rev. Lett. 111, 060803. [3] Wcisło P et al. 2016 Phys. Rev. A 93, 022501. [4] Wcisło P et al. 2016 J. Quant Spectrosc. Radiat. Transfer 177, 75-91. [5] Gordon I E et al. 2017 J. Quant. Spectrosc. Radiat. Transfer 203, 3 – 69. 3

The Suomi National Polar-orbiting Partnership (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS) has been on-orbit for more than 6 years. VIIRS has 22 spectral bands, among which fourteen are reflective solar bands (RSB) covering a spectral range from 0.410 to 2.25 μm. The SNPP VIIRS RSB have performed very well since launch. The radiometric calibration for the RSB has also reached a mature stage after almost six years since its launch. Numerous improvements have been made in the standard RSB calibration methodology. Additionally, a hybrid calibration method, which takes the advantages of both solar diffuser calibration and lunar calibration and avoids the drawbacks of the two methods, successfully finalizes the highly accurate calibration for VIIRS RSB. The successfully calibrated RSB data record significantly impacts the ocean color products, whose stringent requirements are especially sensitive to calibration accuracy, and helps the ocean color products to reach maturity and high quality. Nevertheless, there are still many challenge issues to be investigated for further improvements of the VIIRS sensor data records (SDR). In this presentation, SNPP VIIRS RSB calibration and performance in the past six-year since launch will be presented.

The NOAA-20 Visible Infrared Imager Radiometer Suite (VIIRS) includes several on-board calibration sources for on- orbit radiometric calibration. In the Visible/Near Infrared (VISNIR) and Short-Wave Infrared (SWIR) bands, the on- orbit radiometric calibration is carried out by using a reference called Solar Diffuser (SD). The degradation of the SD surface reflectance is measured by another independent radiometer called Solar Diffuser Stability Monitor (SDSM). These two on-board calibrators provide a degradation-free reference to monitor degradation of the Reflective Solar Band (RSB) detectors. In this study, we describe the characterization and evaluation procedures of SD degradation from the SDSM observations, related on-orbit VIIRS Post Launch Testing (PLT) activities and events within the 100 days of since launch (DSL). The prelaunch version of the SDSM Sun screen transmittance and SDSM SD Bidirectional Reflectance Function (BRF) showed abnormally high oscillations in the H-factors, yaw maneuver derive LUTs were used for version 1 H-factors. The version 2 H-factor was derived from the yaw maneuver data and on-orbit SDSM data sets to fill the gaps between the yaw maneuvers to update the SDSM Sun transmittance LUT. By adding SDSM data set, H-factor versions were mitigated but SDSM detector 6, 7 and 8 showed abnormally high degradation rate compared to the SNPP case. It was caused by the SDSM detector gain changes in these detectors and they were corrected by a ratio approach. Finally, the NOAA-20 VIIRS H-factor results are compared to performance of the near-identical Suomi-NPP VIIRS to identify the best practices for the NOAA-20 VIIRS RSB calibration.

The NOAA-20 Visible Infrared Imager Radiometer Suite (VIIRS) was launched on November 18, 2017 and started to collect Earth view visible/reflective imagery on December 13, 2017. VIIRS has 22 bands, among which 14 are reflective solar bands (RSBs) covering a spectral range from 0.410 to 2.250 μm. The RSBs are calibrated on orbit using an onboard solar diffuser (SD), whose on-orbit degradation is tracked by an onboard SD stability monitor (SDSM). The SD and the SDSM are illuminated by the sunlight through the screens in front of the SD port and the SDSM sun view port only in a very short time period when the instrument passes the southern pole from the night side to day side of the Earth in each orbit. Thus the accuracies of the SD and SDSM calibration strongly depend on the selection of the data collection period, so called “sweet spots”, the accuracies of transmittances of the screens, so called vignetting functions (VFs), and the bidirectional reflectance factors (BRFs) for both SDSM view and the RSB view. In this paper, the “sweet spots” are carefully selected and the BRFs and VFs are accurately derived from the on-orbit yaw and prelaunch measurements. The SD on-orbit degradation, so called Hfactors, and the RSB on-orbit calibration coefficients, so called F-factors, are derived from the SDSM and SD calibrations. The results are presented and compared with those of the SNPP VIIRS. The challenge issues of the RSB calibration using the SD and SDSM are also addressed and discussed.

We describe a new variant of the on-orbit calibration methodology for the reflective solar bands (RSBs) of SNPP VIIRS using the entire illumination interval of the solar diffuser (SD), instead of the smaller “sweet spot” within the illumination interval used by the standard procedure, to compute the calibration coefficients, or F-factors. The instrument response from the full-illumination profile per orbit over the whole mission is directly used to carry out a step-by-step fitting and characterization analysis to arrive at the new F-factors. The new F-factor result is compared with that of standard, lunar-based calibration, and Earth-scattered light approach, expectedly demonstrating very good agreement for bands of longer wavelength but also discrepancies for Bands M1 to M4, the four shortest wavelength bands. The difference is attributed to the angular-dependence in the degradation of the SD that is manifested by the different approaches having different angles of incidence of light to the SD. Thus this result demonstrates the inherent systematic and worsening error for all SD-based on-orbit RSB calibration methodologies to mitigate. On its own, the full-profile approach achieves remarkable stability and robustness on the level of 0.1%, making it a very competitive or better alternative to the current methodology.

The Visible Infrared Imaging Radiometer Suite (VIIRS) on the S-NPP satellite has been in successful operation for more than six years. One of the key performance parameters of the instrument detectors is the saturation of their digital counts (DN). For VIIRS, when the scene spectral radiance level is high enough, before reaching the digital maximum that can be accommodated by the number of bits, the DN for the detector stops increasing and often decreases with increasing scene radiance. Consequently, for some high scene radiances, the pixel spectral radiance calculated from the DN does not accurately reflect the true radiance. To inform the data product user that the calculated pixel radiance may not be accurate, a quality flag is used to indicate that the pixel may be inaccurate. In the current S-NPP VIIRS L1B product, the DN saturation flag is turned on once the DN exceeds a fixed threshold level. In this study, the VIIRS Reflective Solar Band (RSB) detectors’ true threshold levels are characterized by studying their responses to high radiance scenes. The long-term trending of these true threshold levels for each detector is analyzed to examine whether the threshold levels are time dependent. Some saturation effects that may be amenable to correction are also investigated, resulting in more useful data. The results from this study will improve data quality with more accurate DN saturation flags.

The NOAA-20 Visible Infrared Imager Radiometer Suite (VIIRS) was launched on November 18, 2017 and started to collect Earth view visible/reflective imagery on December 13, 2017. VIIRS is a whiskbroom radiometer that provides ±56.28° scans of the Earth view. It has 22 bands, among which 14 are reflective solar bands (RSBs) covering a spectral range from 0.410 to 2.250 μm. The NOAA-20 VIIRS RSBs are much more sensitive to the polarization of incident light than the SNPP VIIRS RSBs. For VIIRS, it is specified that the polarization factor should be smaller than 3% for 410 and 862 nm bands and 2.5% for other RSBs for the scan angle within ±45°. Prelaunch polarization sensitivity tests demonstrated that most of NOAA-20 VIIRS RSBs are out of the polarization sensitivity specification, especially bands M1 and M4, and the polarization are strongly scan angle, detector as well as wavelength dependent. In this paper, it will be shown that the polarization effect induces strong stripping in sensor data records (SDR) Earth view (EV) imagery due to polarization sensitivity differences among the detectors of same band and the stripping are strongly scan angle and band dependent. In this analysis, the polarization effect correction is applied to SDR products to mitigate the impact of the polarization effect. It is demonstrated that the correction can successfully remove the polarization effect in the NOAA-20 VIIRS RSB SDR products and restore the quality of the EV imagery as well as accuracy of EV radiometry for the RSBs.

The first NOAA/NASA Join Polar Satellite System (JPSS-1) satellite was successfully launched on November 18, 2017, becoming NOAA-20. Instruments on-board NOAA-20 satellite include the Visible Infrared Imaging Radiometer Suite (VIIRS). This instrument is the second build of VIIRS, with the first flight instrument on-board NASA/NOAA Suomi National Polar-orbiting Partnership (SNPP) satellite operating since October 2011. The purpose of these VIIRS instruments is to continue the long-term measurements of biogeophysical variables for multiple applications including weather forecasting, rapid response and climate research. The geometric performance of VIIRS is essential to retrieving accurate biogeophysical variables. This paper describes the early on-orbit geometric performance of the JPSS-1/NOAA-20 VIIRS. It first discusses the on-orbit orbit and attitude performance, a key input needed for accurate geolocation. It then discusses the on-orbit geometric characterization and calibration of VIIRS geometry and an initial assessment of the geometric accuracy. This section includes a discussion of an improvement in the geometric model that corrects small geometrical artifacts that appear in the along-scan direction. Finally, this paper discusses on-orbit measurements of the focal length and the impact of this on the scan-to-scan underlap/overlap.

The Day/Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard SNPP represents a major advancement in night time imaging capabilities. The DNB senses radiance spanning 7 orders of magnitude in one panchromatic (0.5-0.9 μm) reflective solar band and provides imagery of clouds and other Earth features over illumination levels ranging from full sunlight to quarter moon. When the satellite passes through the day/-night terminator, the DNB sensor is affected by stray light due to solar illumination on the instrument. Current operational stray light correction for Suomi-NPP VIIRS DNB is based on monthly stray light correction Look-up-Table (LUT) which is separated into LUTs for northern and southern hemisphere. Granules with stray light around new Moon are first visually inspected for minimum light contamination such as artificial light, aurora or other light sources and then are selected for stray light correction LUT generation. This paper developed a light contamination ranking index (LCRI)- based algorithm to automate DNB granule selection and stray light correction LUT generation. This method provides means to evaluate the light contamination quantitatively. In this method, an evaluation region is defined across multiple granules in one orbit for northern and southern hemisphere, respectively. The pixel radiance in the prescribed evaluation region is quantitatively scored with Light Contamination Index (LCI), and percentage of pixels with radiance ratio value above the threshold is evaluated. Imagery quality score can be assessed as percentage of bad pixels in the region of interest. The LCI of DNB images are ranked and images with LCI below certain threshold are selected to ensure containing minimum light contamination. This paper demonstrated the effectiveness of LCRI-method in constructing stray light correction LUT and removing stray light from DNB images.

With comprehensive analysis of the VIIRS DNB on-board calibrator blackbody (OBCBB) data and Earth View (EV) data, it is shown that the DNB OBCBB data can only track the dark current component of the DNB HGS EV dark offset. The DNB observation of deep space during the spacecraft pitch maneuver was also contaminated by star lights. With these acquired knowledge, we propose an improved algorithm for determining the DNB HGS dark offset that is both free from light contamination and capable of tracking drifts continuously. The new algorithm is expected to improve the DNB radiometric performance at low radiance level.

With high demand in performances, ring laser is proposed as an angular measuring transducer, due to its many considerable advantages compared to other means of angle’s measurement, since it’s based on the physical fundamentals, methods, equation/logarithms are developed and experimental work using high precision goniometer, this paper focus on reducing the instability, zero shift, the resolving power to as low as 0.05, the technique required to determine the output frequency within angle of periods in the RL output signals in an entire rotation (2π), The output characteristics instability of scale factor (K₁) and zero shift (K_o ) was observed with time and the effect of instability on the rotational velocity of RL in regard to component error in measurement was minimized, the type of RL used proved to be the square type as different values based on CW and CCW was recorded.

This research work focuses on attaining optimal parameter settings for precise identification of seismic signals at the output of large ring laser gyro through the application of the STA/LTA trigger algorithm. Lately, the sensitivity of rotations has been improved by at least 5 orders of magnitude because of significant upscaling of very large perimeter ring laser gyroscopes. This process in rotational sensors technology brought about the successful detection of rotational signals resulting from earthquakes several thousand of kilometers away. The identification of seismic signals at the output of the large ring laser Gyro may be carried out using the trigger algorithm. As soon as an assumed seismic event is detected, recording and storing of all incoming signals begins. It stops after trigger algorithm 'declares' the end of the seismic signal. The ‘short-time-average through long-time-average trigger' (STA/LTA) is the most widely used algorithm in weak-motion seismology. It constantly calculates the average values of the absolute amplitude of a seismic signal in consecutive moving- time windows. All records, along with those falsely triggered, must be inspected. The completeness of the event records is checked (seismic noise, the P arrivals, the coda waves), and the causes of the false triggers are analyzed. After the evaluation is completed, the parameters are modified consistent with its findings and the new settings archived for documentation purposes. By repeating this process one will progressively discover the satisfactory parameter setting.

A new generation of imaging instruments, the Advanced Baseline Imager (ABI), was launched on November 19, 2016 aboard the first satellite of the Geostationary Operational Environmental Satellite - R Series (GOES-R). This premier satellite became GOES-16 shortly after launch, and replaced GOES-13 as NOAA’s operational GOES-East satellite on December 18, 2017. ABI has 16 bands covering the spectrum between 0.47μm and 13.3 μm to provide continuous data stream for weather forecasting and disaster monitoring. After launch, it is critical to monitor and evaluate the instrument calibration performance in a timely manner using data processed by the GOES-16 Ground Segment, starting at Post-Launch Tests (PLT) and continuing throughout mission life. For this purpose, the GOES- 16 Calibration Working Group (CWG) has developed an Instrument Performance Monitor (IPM) system that includes metrics for GOES-16 ABI striping identification and characterization. In particular, it includes individual band striping identification, flagging, frequency, and image quality provided at minute to mission-life time scales, and sample and pixel level. Using this tool, severe striping in several ABI bands - e.g., band01-03, band05, and band14-16 were characterized. The root cause of striping has been found to predominately arise from calibration algorithm deficiencies and artifacts. Identification and characterization of such striping thus motivates root-cause study and calibration improvement activities. Working as part of the CWG IPM system, the striping identification and characterization metrics help to make the user well informed of Ground Segment implemented calibration improvements and updates for GOES-16 ABI, but also provides clues for resolving anomalies.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on-board the Terra and Aqua space- craft are equipped with several on-board calibrators (OBCs) and continue to operate normally since launch. One such calibrator is the solar diffuser (SD), which allows for the calibration of the 20 reflective solar bands (RSBs) with wavelengths ranging from 0.41 to 2.3 μm. In order to accurately characterize the RSBs on-orbit, the changes associated with the SD bi-directional reflectance factor (BRF) are tracked using a solar diffuser stability monitor (SDSM). The SDSM consists of nine detectors located within a spherical integration source (SIS) and covers wavelengths from 0.41 to 0.94 μm. During each calibration event, the SDSM alternately views sunlight through an attenuation screen and the sunlight reflected from the SD in order to accurately characterize the degradation of the SD at those nine wavelengths. This paper provides a brief overview of the SD/SDSM calibration and operation, with more emphasis on the recent performance of the SD degradation and the SDSM detectors. A methodology to compute the signal-to-noise ratio (SNR) for each of the SDSM detectors is formulated and the noise performance is tracked over the mission lifetime. The importance of the detector noise to the RSB calibration uncertainty and to other instruments, such as the VIIRS SDSM, is also discussed.

The MODIS instruments on the Terra and Aqua spacecraft are cross-track scanning radiometers that view the Earth scene, a space view port, and the on-board calibrators using a two-sided scan mirror. The reflectivity of the scan mirror varies with the angle of the incident light, and changes in this response versus scan angle (RVS) need to be tracked on orbit in order to maintain accurate calibration. In this paper, we review various methods of RVS calibration of the reflective solar bands using pseudo-invariant desert targets and discuss potential advantages and disadvantages for use in future calibration.

NOAA-20 was successfully launched on Nov. 18, 2017. Intensive radiometric calibration and validation activities for VIIRS onboard NOAA-20 were carried out immediately after the sensor data become available. Several bands of NOAA-20 VIIRS such as M6, and M8 have maximum dynamic range requirements or waivers on the saturation value and require post-launch assessment of the impacts on the L1B (or EDR) products. Since the saturation threshold in data processing is defined as the measured Digital Number (DN) count, the corresponding saturation radiance value in the L1B data product can vary due to detector difference and degradation in the sensor optical throughput. On the other hand, users of L1B data care more about the accuracy of scene-dependent radiance value and the impact of detector saturation on the radiance data. In order to validate the detector saturation level and assess their impacts on the radiance data products, histogram-based Probability Distribution Function (PDF) is derived both at detector level and at band level from the daily global radiance data. With such distribution function, the saturation level in radiance can be identified from the sharp fold-over and cut-off at the high radiance value in the distribution. In addition, the percentage of the affected pixels in the global data can be quantified and the detector performance can be compared. Since NOAA- 20 and SNPP are 50 minutes apart in the same orbital plane and have the same equator-crossing time, the probability distribution function method also enables comparison of the radiometric calibration performance between the two sensors. For example, the saturation radiance value for VIIRS M6 on NOAA-20 is ~44.2 (W/m²-sr-um) on 01/11/2018, which is ~26% lower than that of SNPP VIIRS. Such difference can be traced to the more rapid degradation of rotating telescope assembly mirror reflectance in SNPP VIIRS. In addition to saturation analysis, the PDF method allows us to analyze the VIIRS Day/Night Band (DNB) according to the solar zenith angle range, and the performance of stray light correction can be compared between SNPP and NOAA-20 as well.

The Advanced Baseline Imager (ABI) onboard NOAA’s GOES-16 satellite has been operational as GOES-East since December 18th, 2017. It is a multi-channel passive imaging radiometer with 16 spectral bands covering the visible, near infrared and infrared (IR) spectra, to captured variable area imagery and radiometric information of the Earth’s surface, atmosphere and cloud cover. The Level 1B (L1b) radiance images of these channels are geometrically and radiometrically corrected to provide high quality input data to the user communities. Three series of tests are undertaken to validate the product maturity levels: Post-launch Test (PLT), Post-launch Product Test (PLPT) and Extended Validation (EV). Engineering-focused metrics reflecting the radiometric quality of ABI L1b radiance image are assessed in these tests, such as signal-to-noise ratio (SNR)/noise-equivalent-differential temperature (NEdT), background coherent noise pattern, detector dynamic range, detector linearity, etc. Direct Earth view image analysis using image processing tool such as Fourier transform can also reveal information about its quality. In this presentation, initial results of selected PLPTs undertaken by GOES-R Calibration Working Group (CWG) are provided with the focus for IR bands. The results show that the general criterion for product maturity have been largely met. Occasional artifacts still existing at smaller scale are reported. There has been continuous effort to monitor, analyze and resolve these artifacts to further improve the L1b image quality.

The AQUA, SNPP, and NOAA 18-20 PM sun-synchronous satellites were designed with similar local time, local solar zenith angles, and overlapping temporal coverage. Although the satellites are expected to have fixed local equator- crossing time, during the satellite lifetime, the equator-crossing times of these satellites drift. For NOAA 18-19, the drift in equator-crossing time is significant (few hours) and no correction has been done over the lifetime. For SNPP and AQUA, correction in the orbital inclination angle was periodically performed to maintain the equator-crossing time around the designed value. The impact of systematic drift of the local observation time during the satellite life cycle can be significant and should be accounted for when using multi-year time series of satellite products in long-term environmental studies. In this paper, the equator-crossing time drift of AQUA, SNPP, and NOAA 18-20, the correction of SNPP and AQUA equator-crossing time via orbital inclination angle change, and the consequent local solar zenith angle variation are evaluated. The impact of such drift on low-latitude mean brightness temperature trend derived from the similar ~11 μm thermal emissive channel of AQUA MODIS CH31, SNPP Visible Infrared Imaging Radiometer Suite (VIIRS) CH15 and NOAA 18-19 HIRS CH08 are analyzed. The drift in the mean brightness temperature measured by these sensors is combined as a function of local time and analyzed using diurnal cycle analysis. The mean brightness temperature drift for SNPP VIIRS is reconciled within the context of much larger temperature drift of NOAA 18-19.

The MODIS reflective solar bands (RSB) are calibrated on-orbit using a solar diffuser (SD) with its on-orbit degradation, or change in the bi-directional reflectance factor (BRF) monitored using a solar diffuser stability monitor (SDSM). By performing alternate observations of direct sunlight via an attenuation screen and of sunlight reflected diffusely off the SD, the SDSM monitors the on-orbit degradation of the SD. The MODIS SDSM has 9 detectors, covering wavelengths from 0.41 to 0.94 μm. Both Terra and Aqua MODIS instruments have successfully operated for more than 16 years on-orbit, with the SD experiencing significant degradation at the shortest wavelength (about 50% for Terra MODIS and about 20% for Aqua MODIS at 0.41 μm). The first VIIRS instrument on the Suomi NPP spacecraft was launched in October, 2011 and the follow-on instrument was launched in November, 2017 on the JPSS-1 spacecraft (now NOAA-20). Both the VIIRS instruments carry a MODIS-like SD and SDSM system with an improved design based on the lessons learned from MODIS. Unlike MODIS, the VIIRS SDSM collects data using 8 detectors covering a similar wavelength range as MODIS. A similar wavelength dependent SD degradation pattern is also observed in both VIIRS instruments. This paper provides a comparison of the on-orbit performance of the four instruments in terms of the on-orbit changes in the SDSM detector responses and on-orbit degradations of their SDs. The NOAA-20 VIIRS instrument is still in its first year of operation and hence the early performance of the Terra and Aqua MODIS and SNPP VIIRS is discussed to provide a perspective comparison.

Object detection is a fundamental problem faced in remote sensing images analysis. Most of object detection methods mainly focus on single-source image and utilize single spectral or spatial information. Therefore, they are easily affected by illumination angle, brightness and the structure similar to the object. To overcome these defects, a novel object detection framework is proposed using superpixel segmentation and multisource features in multispectral and panchromatic images. During multisource feature extraction stage, the local region spectral information and the spatial information are extracted from multispectral and panchromatic patches respectively. Then, we embed these spectral features into spatial features to construct the new multisource features. During the detection stage, superpixel segmentation method is applied to extract candidate patches based on the superpixel centers from multisource images, which makes detection more efficient. Then, multisource features are also extracted from these candidate patches, which are input to SVM for detection. Experiments are implemented using two groups of the panchromatic and multispectral images by WorldView 2. The results indicated that, compared with single-source detection result, the proposed method can effectively improve the detection performance both on precision and recall rate.

The region of interest (ROI) extraction is of crucial importance in the preprocessing of object detection, especially when the spatial resolution of the remote sensing image becomes extremely high and the field of view becomes relatively large. To conduct the detection approaches directly on the image usually yields unsatisfactory result, and is time consuming. Saliency models based on visual attention mechanism are the general solution to this problem. However, the conventional saliency models deal with the pixel intensity, color statistics or contrast, while neglect the characteristics and spatial distribution of the ROI, which would results in the false alarm in the extraction. In this paper, taken residential area as the region of interest, a ROI extraction method based on saliency, and enhanced by corner density is proposed. The saliency model is adopted to extract the potential area preliminarily. In spite of the efficiency of the model, it suffers from certain defect, that is, the preliminary extracted region contains plenty of false alarms due to the high contrast of bare land and water reflection. Therefore, corner density feature is constructed to refine the extraction, based on the idea of residential area showing higher edge and corner density compared to rural area. In the experimental part, the proposed method is compared with three saliency models. The experimental results reveal that the proposed method is effective in eliminating the false alarm caused by high intensity or contrast of the pixel.

With the development of space satellites, a large number of high-resolution remote sensing images have been produced, so the analysis and application of high-resolution remote sensing images are very important. Recently deep learning provides a new method to increase the accuracy of land-cover classification. This study aims to propose a classification framework based on convolutional neural network (CNN) to carry out remote sensing scene classification. After remote sensing images are trained by CNN, a model which can extract complex characteristic from the image for classification is created. In this paper, GaoFen-2(GF-2) satellite data is used as data sources and Jilin province of China is selected as the study area. Firstly, the preprocessed images are made into a GF-2 satellite data sets. Secondly, CaffeNet is used to train the data sets through Caffe platform and the classification result is obtained. The CNN overall accuracy is 89.88%, the Kappa coefficient is 0.8026. Compared with the traditional BP neural network classification result, it is obviously find the CNN is more suitable for remote sensing image classification.

Building edge or boundary extraction is always one of the most important issues for earth observation, city planning, and other applications. However, for accurately extracting building edge, there are commonly two difficult challenges. Firstly, unwanted strong edges from road and other things can be hardly avoided to be recognized. Secondly, it is more serious that many low or very low contrast weak edges will be not detected. In order to deal with these two issues to a certain extent, in this paper, based on sparse SVM with dual-scale features, we propose a Building Edge Extraction method in a Dual-scale Classification way with Decision Fusion embedded (DC-BEE). Specifically, with global linearity information as priori knowledge, training samples are selected automatically at first. Next, a sparse SVM classifier is trained using the dual-scale local edge features of the training samples. And then, the trained sparse SVM is employed to classify all extracted edges. Finally, the dual-scale decision fusion strategy is performed for final building edge extraction. Visual analysis and quantitative analysis of the experimental results from different style city regions illustrated that the proposed DC-BEE method can efficiently fulfill the building edge extraction task automatically.

In 2015, NSPO (National Space Organization) began to develop the sub-meter resolution optical remote sensing instrument of the next generation optical remote sensing satellite which follow-on to FORMOSAT-5. The multi-spectral strip filter has been developed by NSPO in collaboration with MORRISON Opto-Electronics (MOE) Ltd, meeting the emerging demands of the new TDI CMOS image sensor of the Korsch type optical remote sensing instrument for next satellite mission. This paper represents the technology to deposit the multi-spectral band-pass strip filters on single synthetic silica substrate. The optical multi strip filter is installed in front of TDI CMOS image sensor to capture multi-spectral images of the earth surface. The optical multi strip filter composed of five band-pass filters on single substrate, including three bands in visible bands (400nm to 700nm) called VIS, one panchromatic band including whole visible spectrum and one band in near infrared (NIR). MORRISON Opto-Electronics (MOE) Ltd is responsible to integrate micro-structuring process base on lithography and ion beam-assisted deposition (IAD). These made multi spectral optical thin film coating in a small area with high dimension accuracy deposited possible on the substrate and achieve the robust process of patterning photoresist and removing the photoresist. By repeating the process five times, we have deposited five kinds of band-pass strip filters on single substrate.