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- Plenary Session on Remote Sensing in Asia-Pacific: Present and Future
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Upper Atmosphere
- Optical Remote Sensing of Atmospheric Aerosol Properties
- Optical Remote Sensing of Surface and Cloud Properties
- New Techniques, Instrument Calibration, and Data Validation
- Optical Remote Sensing of Atmospheric Aerosol Properties
- Optical Remote Sensing of Surface and Cloud Properties
- Optical Remote Sensing of Atmospheric Aerosol Properties
- New Techniques, Instrument Calibration, and Data Validation
- Radiative Transfer Modeling and Retrieval Techniques
- Optical Remote Sensing of Surface and Cloud Properties
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
- New Techniques, Instrument Calibration, and Data Validation
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
- Optical Remote Sensing of Surface and Cloud Properties
- New Techniques, Instrument Calibration, and Data Validation
- Optical Remote Sensing of Surface and Cloud Properties
- New Techniques, Instrument Calibration, and Data Validation
- Optical Remote Sensing of Atmospheric Aerosol Properties
- New Techniques, Instrument Calibration, and Data Validation
- Optical Remote Sensing of Surface and Cloud Properties
- New Techniques, Instrument Calibration, and Data Validation
- ADEOS: Instruments, Data Processing, and Science
- New Techniques, Instrument Calibration, and Data Validation
- Radiative Transfer Modeling and Retrieval Techniques
- Optical Remote Sensing of Atmospheric Aerosol Properties
- Radiative Transfer Modeling and Retrieval Techniques
- Optical Remote Sensing of Atmospheric Aerosol Properties
- Radiative Transfer Modeling and Retrieval Techniques
- Optical Remote Sensing of Surface and Cloud Properties
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
- New Techniques, Instrument Calibration, and Data Validation
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
- ADEOS: Instruments, Data Processing, and Science
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
- Radiative Transfer Modeling and Retrieval Techniques
- ADEOS: Instruments, Data Processing, and Science
- New Techniques, Instrument Calibration, and Data Validation
- Optical Remote Sensing of Surface and Cloud Properties
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Upper Atmosphere
- Radiative Transfer Modeling and Retrieval Techniques
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Upper Atmosphere
- Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
- Radiative Transfer Modeling and Retrieval Techniques
- Optical Remote Sensing of Surface and Cloud Properties
Plenary Session on Remote Sensing in Asia-Pacific: Present and Future
Strategy of simultaneous remote sensing of aerosol optical depth and surface reflectance with spaceborne spectrometry
Daren Lu,
Minzheng Duan
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In quantitative remote sensing of atmospheric and earth surface parameters with space-borne optically spectral sensors, atmospheric correction and surface (background) influence deduction are key steps for both surface and atmospheric remote sensing, respectively. In principle, these two steps are with same task, i.e., decoupling or separation of respective contributions to spectral radiance (or normalized reflectance) observed by spaceborne sensors. A lot of efforts have been paid to solve this problem. Most of them are using supplementary information obtained by ground-based observation or
climatological means for the atmosphere or surfaces. Owing to the limitations of simultaneous surface measurements and temporal and spatial variation of the atmosphere and earth surfaces, above-mentioned efforts are always faced significant error or very limited usefulness. It is commonly recognized that the best or ideal way is simultaneous remote sensing of the atmosphere and surface with spaceborne sensors alone (with least assumptions). There are at least three approaches towards simultaneous remote sensing, i.e., multi-angle measurements, multi-spectral measurements, and multipolarization measurements. In different assumptions, each of them may apply to simultaneous remote sensing. After general discussion, this paper will mainly focus on the approach with multi-spectral observation in Visible-NIR waveband. The present approach includes two steps, the first step is to establish approximate formulae which may explicitly give quantitative contribution of the atmosphere and surface to satellite-borne sensor's measurements. The
second step is to establish retrieval scheme by using the above mentioned formulae and the spectral dependence of both the atmospheric optical depth and surface reflectance, details about principle and preliminary numerical simulation are given in following sections.
Composite satellite system for global environment observation and international cooperation
Fangyun Chen,
Ainai Ma
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A composite Earth environment observation satellite system is proposed in this paper. The first step is the full utilization of the present meteorological satellites and Earth resources satellites. The second step is to implement two groups of small remote sensing satellites systems, one is of optical sensors (visible spectrum and infrared) and the other is of microwave radiometers, for monitoring the changeable Earth environments. And the third step is to launch a few RADARSATS for observation through the cloud covering. We believe the proposed system could do great benefit to the global and regional monitoring and study in spatial and temporal scales. The two multiple small satellite systems are described in greater detail in this paper, and the results of preliminary design are given. The proposed global system is presented for discussion as a possible program for international cooperation of the Asia-Pacific Area.
IMG: precursor of the high-resolution FTIR on the satellite
Hirokazu Kobayashi,
Toshihiro Ogawa,
Haruhisa Shimoda,
et al.
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The Interferometric Monitor for Greenhouse gases (IMG) was the precursor of the high-resolution sensor of Fourier transform
infrared spectroscopy (FTIR) boarded on the satellite for Earth observation. The IMG was boarded on the Advanced Earth Observing Satellite (ADEOS) launched by the National Space Development Agency of Japan (NASDA) on Aug. 17, 1996. The IMG sensor operated for only 8 months, however, the obtained high-resolution thermal infrared spectra provided abundant information on global atmospheric phenomena, and the first global maps of greenhouse gases were retrieved from these spectra.
Development and application of hyperspectral remote sensing in China
Qingxi Tong,
Lanfen Zheng,
Yongqi Xue
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The development of hyperspectral remote sensing has been conducted in the middle 1980s. Since then a number of hyperspectral imagers has been developed. The spectral response of it has covered the visible, near infrared, shortwave infrared and thermal infrared regions. In some time of the technical developments, the applications in various areas have also been conducted. For mineral exploration, the difference minerals as well as the alteration zones have been analyzed and extracted. Hyperspectral imagery enabled the detailed classification of vegetation. In case of study of wetland environment, some subspecies of wetland vegetation have been distinguished. Based on the spectral characteristics of vegetation and some artificial objects the urban environment and mapping have been tested by using of the hyperspectral remote sensing integrated with high spatial resolution data. In the studies the thermal infrared multispectral remote sensing has also been developed and dealt with the geological application.
Remote sensing of vertical profiles of atmospheric trace constituents with MIPAS limb emission spectrometers
Herbert Fischer,
Hermann Oelhaf
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In order to understand better periods of significant ozone depletion and long-term ozone trends numerous atmospheric constituents need to be measured simultaneously on a global basis. Fourier-transform infrared spectrometers are especially suited for this measurement task. A promising and challenging branch of Fourier-transform infrared spectroscopy is its application to limb emission sounding by the use of cryogenic instrumentation. The MIPAS (Michelson interferometer for passive atmospheric sounding) balloon-borne (MJPAS-B) and space-based (MIPAS-S) experiments apply this technique. While the MJPAS-B instrument has already been used for several years for stratospheric process studies, the MIPAS-S instrument is being constructed for the European Space Agency's ENVISAT mission. Instrumental aspects of these MIPAS experiments are briefly highlighted. The most important results in ozone research achieved with MIPAS-B in middle and high northern latitudes are reviewed. In addition a brief overview of the measurement capabilities of the MIPAS space experiment will be given.
Monitoring stratospheric compositions by ground-based instruments in China
Beiying Wu
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Ground based monitoring of stratospheric composition has been carried out in China since 1960s. The mainccompositions detected are ozone and aerosols. Total column and the profile of ozone have been measured by Dobson, Brewer and lidar. Volcanic aerosols from the eruptions of El Chichon and Pinatubo have been monitored by lidar and
polarimeters. This paper will introduce the main progress in this area in China.
SAGE III/EOS
W. P. Chu,
Robert Veiga
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This paper describes the SAGE III (Stratospheric Aerosol and Gas Experiment III) experiments as part of the EOS program for long term monitoring of the atmospheric ozone and aerosol for global change study. SAGE III carries the heritage from the previous sensors SAM II, SAGE I, and SAGE II, which have provided stratospheric and tropospheric measurements of key atmospheric species such as aerosol, ozone, nitrogen dioxide, and water vapor. In addition to those atmospheric species, SAGE III will measure profiles of temperature, pressure, chlorine dioxide, and nitrogen trioxide using the solar and lunar occultation techniques. Three SAGE III instruments will be launched between 1999 and 2002. The First SAGE III will be on a Russian Meteor 3M spacecraft to be launched in 1999. The second SAGE III will be on the Space Station in 2002. The third SAGE III instrument is for a Flight of Opportunity, most probably will be flying in an inclined orbit for global coverage in 2001. The mission's science objectives, in terms of providing global measurements of key species for climate change study, and the algorithms used to retrieve the geophysical information from the measurements will be discussed.
Improved limb atmospheric spectrometer (ILAS): validation and preliminary scientific results
Yasuhiro Sasano,
Makoto Suzuki,
Tatsuya Yokota,
et al.
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Improved Limb Atmospheric Spectrometer (ILAS) on board the Advanced Earth Observing Satellite (ADEOS) obtained 8-months data for stratospheric ozone layer over the high-latitude regions in both the southern and northern hemispheres. Main parameters observed by ILAS were vertical profiles of ozone, nitrogen dioxide, nitric acid, nitrous oxide, methane, water vapor, aerosol extinction coefficient (at 780 nm), temperature, and pressure. Products from ILAS measurements were validated with correlative measurement data. The instrument and data processing scheme will be overviewed, and some
results of validation and preliminary scientific analyses will be presented.
Meteorological satellite program of China
Wenjian Zhang
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China has been making her unremitting efforts on pushing her meteorological satellite program and building up the meteorological satellite as well as data application systems. The meteorological satellite program of China consists of two major systems: Polar-orbiting system and geostationary system. The main objectives of the program are to establish, with combination of polar and geostationary orbits, a comprehensive operational meteorological satellite system as well as data application systems around the turn of the century, in order to meet the needs on various aspects in China, and enhance the capability of participating international collaboration.
NPOESS program and the performance of advanced infrared sounders
Mitchell D. Goldberg,
Donald Blersch
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The NPOESS program merges the United States military and civil operational meteorological satellite systems. The convergence of both systems result in significant cost savings and most importantly increase system performance. An example of improved performance is the inclusion of an advanced high spectral resolution infrared sounder, which will greatly improve the accuracy of satellite temperature and moisture soundings and is expected to yield significant improvements in numerical weather prediction. Further benefits include nowcasting and climate studies.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Upper Atmosphere
Airglow measurements in the upper atmosphere
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Airglow measurement is an important method of studying the dynamic processes in the upper atmosphere. In this paper, we will provide a brief review for airglow measuring methods of atmospheric wind, temperature and short-period wave process in the thermosphere and mesopause region. First, we give the measuring principles, application and major measured result of Fabry-Perot optical interferometer used to the measurement of atmospheric wind and temperature. Then, airglow measurements in the mesopause region are discussed, and a brief description of the tilting-filter photometer developed by CSSAR is given. Finally we will give an introduction on the future plane of upper atmospheric optical measurements in China.
Optical Remote Sensing of Atmospheric Aerosol Properties
Optical properties of tropospheric aerosols derived from lidar measurements over Hefei
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In this paper, the solution to lidar equation for tropospheric aerosol monitoring is introduced. System structures and characteristics for L300 lidar are presented. Observation method and data processing procedure are described. Optical properties of tropospheric aerosols determined by the lidar measurements over Hefei are analyzed and discussed.
Effects of surface and atmospheric aerosols on several POLDER channels
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Atmospheric aerosol enhance greatly the atmospheric scattering which decrease the signal to noise ratio of the satellite images. It is therefore important to correctly estimate and remove the effects of the atmospheric aerosols on signals from the underlying surfaces. Depth of the absorption band of oxygen molecules at 760 nm wavelength will be changed by multiple scattering. The new generation of space-borne spectrometers under development provides sufficient spectral resolution to detect this effect. This paper discuses the possibility to distinguish the type of aerosols and retrieve aerosol optical depth from the variation of the features of the A-band at 760 nm. It is shown that this effect can be used to classify aerosols when aerosol optical depth is very large or for cases over typical land surfaces. For the visibility ranging from 5 to 20 km. Aerosol optical depth can be retrieved accurately over the ocean even if the type of aerosols is unknown. Therefore, this method can provide valuable information to current atmospheric correction and spaceborne aerosol-retrieval schemes.
New remote sensing methods of aerosol optical properties and their application
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Some new remote sensing methods of aerosol optical properties and their basic principles are described. The methods are the wide-band extinction method for deriving aerosol optical depth from global direct solar radiation detected by pyroheliometer, the method for retrieving aerosol imaginary index from downward diffuse solar radiation, and the method for deriving aerosol optical depths from joint surface visibility and water vapor pressure. These methods are used to determine aerosol optical depths over 12 meteorological observatories in China during 1980-1994, to retrieve aerosol imaginary index over Beijing and Wulumuqi, and to built aerosol optical depth map in China. Some inversion results are analyzed.
Optical Remote Sensing of Surface and Cloud Properties
Studies on remote sensing of cirrus cloud properties using near- and far-infrared water vapor bands
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In the modeling study, the characteristics, of the wavelengths ranging from the visible, near IR, and entire thermal IR spectra up to 40 μm have been investigated systematically. We find that the wavelengths of 1.38 μm and 25.0 μm located, respectively, in the near- and far-IR water vapor bands are superior to the other IR channels and have potential possibility of remote sensing of microphysical and optical properties of cirrus clouds.
New Techniques, Instrument Calibration, and Data Validation
Deconvolution method of atmospheric spectra and its application in atmospheric remote sensing
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In this paper, we discuss the method of spectrum deconvolution and its application in the atmospheric remote sensing. This paper consists of three respects of content. First, we discuss the influence of the spectrum resolution of the instrument on the atmospheric remote sensing detectable height. In the second part of this paper, we discuss the deconvolution method of the atmospheric absorption spectra and its ability of spectrum resolution enhancement. Finally, we will discus the application of the atmospheric spectrum deconvolution method in the ground-based atmospheric remote sensing. Two methods of the atmospheric inversion that use the atmospheric spectrum deconvolution method to increase the resolution of observed spectrum will be presented. One is the effective instrument function method. Another is the circulation method of ground-based atmospheric remote sensing inversion. The study indicated that the spectrum deconvolution method can be used to increase the detectable altitude of the ground-based atmospheric remote sensing.
Optical Remote Sensing of Atmospheric Aerosol Properties
Comparison of chemical composition parameterization with optical retrieval for determining aerosol apparent refractive index
Fang Li,
S. Nyeki,
U. Baltensperger
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Aerosol refractive index is an important parameter relating its chemical composition with optical properties. Contained within this paper is presentation of two approaches to estimate the aerosol apparent complex refractive index: one is the partial molar refraction approach (PMRA) based on aerosol chemical composition analysis, and another is the light extinction retrieval (LER) from the aerosol scattering and absorption properties. Both are applied to the field measurement data of a continuous experiment for three months at the Jungfraujoch high-alpine station. The three-month median of the real part of the refractive index from the PMRA is 1.52 +/- 0.04, and the imaginary part is 0.003 +/- 0.002. Comparison of the results from the PMRA with those from the LER is made for the simultaneous measurements. Consistence of them is within 5 percent for the real part of the refractive index, and within a factor of 2 for the imaginary part.
Optical Remote Sensing of Surface and Cloud Properties
Cloud distribution characteristics over the Tibetaan plateau
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We use GMS5 satellite data and ISCCP cloud detection algorithm to study the characteristics of monthly mean cloud distribution and diurnal variation over the Tibetan Plateau. We simply classify total cloud into low, middle and high categories according to the height of cloud top. For the spatial distribution, during winter season both total and high cloud amounts of the north part of the Tibetan Plateau are larger than that of the south part of the Tibetan Plateau, but during summer season the distribution patterns are the reverse, that is, the cloud amounts of the south part of the Tibetan Plateau are larger than that of the north part of the Tibetan Plateau. For the diurnal variation, the total cloud amount begins to increase after sunrise and reaches maximum at 09GMT and 06GMT for midsummer season and other months respectively. After that total cloud amount decreases slowly. But the diurnal variation of high cloud amount is different from that of total cloud amount, high cloud amount begins to increase at noon time and reaches maximum at 09GMT and 12GMT for winter and summer seasons respectively. The diurnal variation of both total and high cloud amounts of the Tibetan Plateau is larger than that of the north part of the Indian Island.
Remote sounding technique of cirrus cloud and aircraft flight experiments
Zhaoxian Zhang,
Mochang Wang,
Xingan Jiang,
et al.
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Considerations on channel selection and the design of Cirrus Cloud Sounder (CCS) are presented. The aircraft flight experiment for CCS was made in May 1997 along two airlines.Processing and analysis of the measurements were made and a primary algorithm for detecting cirrus and other kinds of clouds was summarized.
Optical Remote Sensing of Atmospheric Aerosol Properties
Comparing experiments of digital photography visiometer
XingSheng Xie,
ShangChang Tao,
XiuJi Zhou
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This paper reports a digital photography visiometer (DPV), an automatic digital photography visibility system, that can directly measure and monitor horizontal visibility during daytime through digital shooting. After shooting a scene of given black object and background via its CCD digital camera, the system can capture and transfer photographic images in the camera to a computer, as well as process the digital images and calculate the value of visibility. The formulas for calculating visibility with this method and analyzing the effect of non-black object on measured result are also given. And then the comparison of DPV observations with a lidar-visibility measurements and visual observations are carried out. The results show that the average deviation and relative average deviation of visibility acquired by DPV from lidar-visibility measurements are respectively within 0.927 km (and 0.26 km) and 6.68 percent (and 7.99 percent).
New Techniques, Instrument Calibration, and Data Validation
Noise analysis of lidar backscattering signal using forward and backward Kalman filtering algorithm with generalized random walk structures
Jialing Gao,
Zunan Wu,
Zhongliang Chen,
et al.
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Recursive estimation of high-frequency noise in lidar backscattering signal based on forward and backward linear Kalman filtering algorithms are exploded. Using state-space techniques, the lidar aerosol backscattering signal is identified following generalized random walk (GRW) structures. Comparisons of the estimation results between different Kalman-GRW filters are given in case studies. The spectral test of the given examples show that the forward and backward Kalman filtering algorithms processing with the GRW structures low-pass filters for the smoothing of lidar data.
Radiative Transfer Modeling and Retrieval Techniques
Advanced retrieval method in satellite remote sensing atmosphere: the technique of computed tomography
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Computed Tomography (CT) is a modern medical diagnostic technique in which x-ray transmission measurements at numerous angles through the human body are processed by computer to produce cross-sectional pictures of the body. This technique also has found applications in such diverse fields as materials testing, astronomy, microscopy, image processing and oceanography.In this paper, a modification of this technique, using emitted IR or microwave radiation instead of transmitted x-ray radiation, can be applied to satellite radiance measurements taken along the orbital track at various angles. The channels of IR sensors for the CT retrieval are selected from HITRAN Database, and analyzed by Eigen-value analysis. We discuss in detail the effect retrieval result of CT technique form projection-angle. Finally, using the balloon sounding data, the result of CT are compared with the result of conventional method. Because the advantage over conventional remote sensing methods is the additional information acquired by viewing a given point in the atmosphere at several angles as well as several frequencies. The results show that the temperature profiles by CT retrieval are better than the conventional method.
Optical Remote Sensing of Surface and Cloud Properties
Snow cover monitoring with microwave and other channels of TOVS
Ruiyun Liu,
Jingning Luo,
Lujun Guo
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TOVS data is used to monitor snow coverage in this study. The spectral difference between MSU-1 (centered at 50.31 GHZ) and HIRS/2-8 (centered at 11.lOμm) is used to identify the cloud free area;
the MSU-1, HIRS/2-8 and HIRS/2-19 (centered at 3.7Oμm) are combined to screen out the non-snow target with high albedo; finally the reflection character of HIRS/2-20 (centered at O.7Otm) is used to distinguish snow. Two tests were made to compare with the real cases of snow coverage in East China in January 1993, and the east of Tibetan Plateau in 1991.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
GPS remote sensing precipitable water in typhoon and severe storm background
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The principle and method of remote sensing precipitable water by Global Positioning System (GPS) are introduced. A series of tropospheric delay are obtained from the dual frequency receiver's data of global tracking stations in East Asia and precise satellite ephemeris of IGS from July 31 to August 20, 1997. During this period, typhoon and severe storm passed through the region several times. The continuous precipitable water (PW) with the interval of 30 minutes are estimated at Shanghai and Wuhan GPS sites. The results are compared with PW from conventional radiosonde during the same period, and the RMS is about 0.50 cm. They fit well in main tendency and agree with each other at most of the time, especially when severe storm affects the region. The continuous change of precipitable water reflects the weather process precisely.
New Techniques, Instrument Calibration, and Data Validation
Remote sensing of lightning return stroke current parameters: feasibility and uncertainty
Boayou Zhu,
Shanchang Tao
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Recently, lightning location system with LF/VLF bandwidth has been widely used in the world, therefore it is interesting to investigate the feasibility and uncertainty of deriving lightning return stoke current parameters from remote electromagnetic fields measured by lightning location system. Calculations are presented to check the validity of the electric field expression which was given by Uman [1970] on hypothesis of Transmission Line Model (TLM), and the results show that TLM somewhat underestimates the peak of the currents and the risetime of current deduced from the model may be unconvincing. A modified expression dealing with the peak of electric field vs. the current is developed by using modified transmission line model as well as taking into account propagation attenuation and effect of slant lightning certainty of the derived current peak depends on the truth of the assumed return stroke (RS) velocity and the precision of measured electric field and distance. Due to propagation effect the risetime of the electric field is different from that of the current and the increase of the rise of the electric field against that of the current varies with propagation conditions and the current waveform. The risetime of current waveform can be roughly estimated form that of the electric field waveform, but there exists considerable uncertainty due to uncertainty of assumed ground conductivity.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
Column abundance of atmospheric CH4 and precipitable water measurements from ground-based infrared solar spectra
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Infrared solar spectra were measured automatically by an infrared solar spectrometer (ISS) capable of 0.4 cm-1 resolution. Good signal-o-noise ratio (SNR) and relatively high resolution made it possible to select unsaturated, temperature insensitive intervals for a specific absorption gas with minimal overlap by other interfering gases. In the wavelength range of 3.410-3.438μm, the absorption is mainly due to atmospheric methane and water vapor. A line-by-line (LBL) computation method was used to calculate theoretical atmospheric absorption. By adjusting the total column density to obtain an exact agreement between the calculated and observed absorption, the total column density of atmospheric methane and water vapor were obtained. In the paper, some result observed by ISS for more than one year were reported. Since the April of 1997, we have been monitoring the column abundances of atmospheric CH4 and H2O continually on every clear cloudless day with the method indicated above. The results show that CH4 has little variation in one day, but has considerable seasonal variation. More than one high density peaks were found, two of which occurred in hot summer and cold winter, and the smallest value was found in spring. The reason is explained as emissions of local sources and atmospheric transport. The precipitation of column water vapor has a largely variation even in one day, the smallest precipitation appeared in winter, the biggest value was found in hot summer, seasonal variation could be as large as 40 times.
Optical Remote Sensing of Surface and Cloud Properties
Extraction of satellite cloud texture features and automatic cloud classification
Desheng Fu
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Based on the gray scale distribution on satellite cloud pictures (SCP), the gray level co-occurrence matrices are delt with, followed by cloud texture features sampled for identifying their characteristics quantities. Thus, the equation of automatic SCP classification is established for the purpose of microcomputer grouping.
Estimating surface radiation budget over China in summer from GMS satellite data
Weimin Chen,
Qingxian Gao,
Gang Hong
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The surface radiation budge is an important essential radiation parameter. In this paper, the basic relation between the measurements from the visible/IR channel in satellite and the surface radiation budgets has been derived. According to this relation, some useful models of estimating the surface radiation budget are obtained by the observational data from the visible/IR channel in GMS satellite and the observational data from surface radiation budget stations. With the most excellent one of these models, the distribution of radiation budget across China is obtained by the interpolation method. Compared to the actual observational data, this distribution has a better consistency with the actual result, which shows that this model is very effective in estimating the radiation budgets in China.
Estimating solar direct and diffuse radiation in a cloudless atmosphere from satellite data
Weimin Chen,
Bingsang Fu,
Duo Bian
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Based on the theory of multiple scattering of radiation in a plane parallel atmosphere, solar direct and diffuse radiations in various spectral bands at different heights have been computed with the discrete ordinate algorithm using the radio observations, radiative observations, and retrieval from the TIROS/N operational vertical sounder (TOVS). The LOWTRAN program is also used for computation of radiative transfer parameters such as optical thickness. The computed radiation are then used to set up the statistical relationship with satellite observations in the VIS and IR. The results have shown that the correlation coefficient is up to 0.9 in the upper atmosphere and 0.70-0.85 in the lower atmosphere. Thus satellite observations in the VIS and IR channel may be used to estimate the solar direct and diffuse radiations in a cloudless atmosphere.
New Techniques, Instrument Calibration, and Data Validation
Monitoring severe drought in northern China in 1997 using meteorological satellite remote sensing
Qianguang Xiao,
Weiying Chen,
Peng Du,
et al.
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During the summer of 1997, the air temperature is the highest in the same periods during recent forty years. On the condition of low precipitation and high evapotranspiration driven by it, severe drought happened in the north of China. Several methods of monitoring summer drought using NOAA meteorological satellite data are described in this paper. When vegetation cover is relatively low, thermal inertia method can be used to monitor drought. However drought often happens in summer, during which vegetation cover is relatively high. In order to solve this problem a new method, called Water Supplying Vegetation Index (WSVI), was developed. This new method detects drought information by combining vegetation with temperature retrieved from NOAA satellite data. The drought range and degree can be obtained using WSVI method. In order to verify these results, the satellite-monitored results are compared with the precipitation anomaly and soil moisture observed by agricultural meteorological stations. Compare indicates a close relationship between remote sensing methods and meteorological observation methods. The remote sensing methods are better than conventional methods in the observation range and accuracy.
Observation and analysis of solar spectral radiation in solar eclipse at Mohe
Jianhui Bai,
Qinxin Kong
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The observation data of solar UV, visible, IR and total radiation during the 9 March 1997 solar eclipse at Mohe have been analyzed, results are the following: during period of solar eclipse, variation trends of solar UV, visible, IR and total radiation were similar, their energy deficits and percentages of energy deficit increased area of the sun 's surface covered by the moon's umbra, and reached the maximum of the solar eclipse. The energy losses of solar UV, visible, IR and total radiation in solar eclipse were 0.09, 0.55, 0.72 and 1.28 MJ/m2, respectively. There were still good relationships among solar UV, visible, IR and total radiation during the solar eclipse.
Optical Remote Sensing of Surface and Cloud Properties
Sea surface temperature retrieval from geostationary meteorological satellite (GMS-5) infrared split-window channels
Weiying Chen
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This paper describes algorithm of cloud detection and atmospheric correction for deriving sea surface temperature using GMS-5 IR split-window channels. It also briefly introduce GMS-5 Sea Surface Temperature (SST) operational processing system. The comparative result of SST retrieved from GMS-5 with the conventional measurements from ship show that root mean square deviation is about 1.2 degrees C.
New Techniques, Instrument Calibration, and Data Validation
Easily performed method of solar total irradiance measurement in space
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For usual solar total irradiance monitor, the absolute radiometer is mounted on a sun auto tracking system. This paper introduces a new method of measuring solar total irradiance on Heliosynchronous Polar-Orbit Satellite. The solar total irradiance monitor is made up of the three same absolute radiometers with ±7.5° field-of-view which are mounted onto one section plane. Because the angle between the orbit plane and solar meridian plane is stationary for sun-synchronous polar-orbit satellite, the three radiometers are mounted on the plane which is parallel to the solar meridian plane. When the satellite runs in orbit, measurement will be taken at the overhead time when the sunscans over the three radiometers' field of view respectively. The three absolute radiometers are cavity electrically-calibrated absolute radiometers with measurements precision and uncertainty of less than 0.05 percent and 0.2 percent, respectively. In our method, since the variation of primary aperture area with angel is different from that of tracking mode, we use a simplified model in which the area variation with angle is expressed by cosine function. Formulae and curves obtained by differential equation of thermodynamics of the simplified mode in non-tracking model are similar with that in the sun- tracking mode. The theoretical analysis and simulation calculation proved the precision by our method could reach the same level as that of the sun-tracking mode, but the construction of instrument is much simple.
Remote sensing model for CO2 flux in wheat fields
Renhua Zhang,
Xiaomin Sun,
Zhilin Zhu,
et al.
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In this paper we presented a model for calculating CO2 flux in the wheat field based on field simulate test. We adopted crop transpiration as 'information picker' of CO2 flux instead of the potential evaporation and crop water stress index. Another crucial factor is leaf index and air vapor saturation deficit. Experimental coefficient is equal to 1/58. Calculating values have a good agreement with real measurements. The model is useful to estimate regional distribution of CO2 flux.
Optical Remote Sensing of Atmospheric Aerosol Properties
Study of dust storms in China using satellite data
Xinjiang Zheng,
Feng Lu,
Xiang Fang,
et al.
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Northwest China is a major region of dust storm. With NOAA and GMS-5 satellites, the dust storms can be effectively monitored. The relationship of the distribution of dust storm and the Normalized Difference Vegetation Index is discussed, it is pointed out that the dust storm frequently occurs at the areas with few vegetation cover, such as desert or Gobi. Several cases used with ANHRR/NOAA and GMS-5 satellite images are presented in the paper for the monitoring of the dust storms.
New Techniques, Instrument Calibration, and Data Validation
Staring imager concept for a geostationary orbit meteorological satellite
Dunjie Cui
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With reference to GOES-9 5-channel Imager and use of 5000-by-5000 pixels areal array CCD and 1000-by-1000 pixels IR FPA, a conceptual design of a staring optical remote sensor for the Geostationary Orbit Satellite has been carried out, and the characteristics that this sensor can reach is discussed and compared with the reference sensor, the results demonstrate that the staring sensor is superior to the scanning-type sensor in the aspect of mass, power assumption, viewing efficiency, frame refresh duration, etc.
Improvement of Changchun satellite laser ranging system
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Satellite Laser Ranging (SLR) is a very important technical means in geodesy and geodynamics. It is also a very important tool to calibrate the spaceborne altimeter, such as Geos-3, Seasat, Geosat, ERS 1 and 2, TOPEX/Poseidon, and just launched GFO-1, and it is the only way to calibrate the spaceborne altimeter satellite on-orbit. So the precision and accuracy of SLR system will play an important role in determining the measurement accuracy of the altimeter. This paper presents the improvement of range precision and stability laser ranging system in Changchun Artificial Satellite Observatory, the range precision and stability of the satellite laser ranging system have been greatly improved. A high quantum efficiency, low time walk, compensated, low work voltage and fast response time single photon avalanche diode was applied to the system, besides a portable calibration system and three new near ground targets. Now, the system produces subcentimeter single-shot precision and precision for mm level for normal point data. The long term system stability is improved from 4 cm to better than 2 cm, the range bias is less than 6 cm, and the time bias is less than 50 μs.
Optical Remote Sensing of Surface and Cloud Properties
Calculating surface reflection characteristics by optical remote sensing
Quanhua Liu
Show abstract
A retrieval algorithm for calculating surface bi-directional reflectance from satellite measurements is developed with the matrix operator method. In method is applied in the matrix operator method, which makes the mathematical derivation of the explicit expression simple and straightforward by exactly decoupling the surface reflection term from the radiance and the atmospheric terms. It is shown that the explicit expression is very stable mathematically. Sensitivity test show that the mean random error of 10 percent in the aerosol profile has little effect on the retrieval of the surface bi-directional reflectance. The retrieval error can reach about 2 percent on average when maximum random error of 5 percent is introduced in the satellite measurements. The present method is limited to the clear-sky case. An application is carried out based on the field of radiance, which were made with the Earth radiation budget (ERB) instruments on the satellite Nimbus 7. The retrieved bi-directional reflectance from the ERB measurements for desert surface, land surface, and snow surface show the anisotropic behaviors of the surface reflection. They all have the large anisotropy for large viewing angles. The snow surface has a strong anisotropy of reflection in the forward direction, indicating somehow mirror reflection.
New Techniques, Instrument Calibration, and Data Validation
Preliminary results on the performance degradation of Earth radiation spectra measured by GOME
Cristina P. Tanzi,
Ernst Hegels,
Ilse Aben,
et al.
Show abstract
The Global Ozone Monitoring Experiment (GOME) is a nadir-viewing spectrometer covering a broad wavelength range, from the UV to the near infrared. It has been operating since 1995 on board the ESA ERS-2 satellite, monitoring a large range of atmospheric trace constituents, with particular emphasis on ozone. The performance of the instrument is monitored in- flight by means of routine on-board calibration measurements, observing the sun and, occasionally, the moon. In this way, degradation of optical components in space can be monitored. For example, the performance of the broad-band detectors which monitor the polarization state of the incoming light is analyzed by means of solar measurements. The measurements of the polarization detector which samples UV light show a degradation of 6 percent per year. The optical components affected have been identified by monitoring the fractional polarization, which is a characteristic of the light back-scattered by the Earth's atmosphere. The influence of the observed degradation of Earth radiation measurements is estimated to be in the order of 1.5 percent per year in the UV wavelength range.
ADEOS: Instruments, Data Processing, and Science
Intercomparison of ILAS/ADEOS with MIPAS-B measurements in late March 1997
Hermann Oelhaf,
Herbert Fischer,
Gerald Wetzel,
et al.
Show abstract
Embedded in the ILAS validation campaign a balloon flight was carried out with the limb emission sounder MIPAS-B in the early night of March 24, 1997. MIPAS-B is capable is capable of simultaneously measuring profiles of all molecules ILAS was covering. Key reservoir molecules like ClONO2 and N2O25 which are not or hard to measure with ILAS complement the ILAS set of target species and allow the partitioning and budge to NOy to be studied. The balloon was launched from Kiruna/Sweden. The distance of the mean location of tangent points between the satellite and the balloonborne observation was less than 150 km and the time was offset by less then 4 hours for the most adjacent overpass of ADEOS. The balloon observations covered the altitude range of 11.0 to 29.5 km. Vertical profiles of N2O, CH4, H2O, HNO3 NO2 and aerosol extinction obtained with MIPAS-B have been compared to those obtained with ILAS based on the three most adjacent ADEOS overpasses. Model calculations with the 3D chemical transport model KASIMA were used to account for nay deviations in the dynamical and chemical properties of the airmasses observed at the different times and locations of observation. The paper demonstrates the progress made in the consistency of the data sets when going from Version 3.0 to Version 3.1 of the ILAS data processing software. Excellent agreement between balloon and satellite observation has been found for HNO3 on the basis of the Version 3.1 results. The same holds for NO2 above 20 km provided the diurnal variation is taken into account. Discrepancies still exist with the Version 3.1 results in the lowermost part of the stratospheric for most gases and generally in the case of N2O.
New Techniques, Instrument Calibration, and Data Validation
Characterization of a hardened ultrastable UV linear variable filter and recent results on the radiometric stability of narrowband interference filters subjected to temperature/humidity, thermal/v
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A series of in-band and out-of-band transmittance measurements of filters covering the wavelength range from 317 to 1019 nm and a linear variable filter for the 300 to 400 nm range have been made. The bandpass filters and the linear variable were fabricated using the ion-assisted-deposition or similar processes. The radiometric stability of the central wavelength, bandpass (FWHM), and peak transmittances were measured before and after exposures to combined high temperature and humidity, a thermal vacuum cycle, an ionizing particle radiation environment, flight on the Space Shuttle and at two temperature ranges. Representative radiative signal-to-noise ratios are given for solar irradiance observations with a silicon photodiode detector.
Radiative Transfer Modeling and Retrieval Techniques
Retrieval of carbon monoxide, methane, and nitrous oxide from SCIAMACHY measurements
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The atmospheric spectrometer SCIAMACHY to be launched on board ESA's Envisat satellite in 2000 will measure UV, visible and IR spectra from nadir, limb and occultation with spectral resolution between 0.2 and 1.4 nm. SCHIAMACHY's channel 8 covering the wavelength range 2265-2380 nm will allow the global determination of concentrations of methane, carbon monoxide and nitrous oxide. Sensitivity studies using the most recent values for the instrument parameters show that the minimum values for the accuracies for total vertical columns are of order 5 Dobson units (DU) for carbon monoxide, 3 DU for methane, and 6 DU for nitrous oxide, for a 1 s SCIAMACHY nadir observation. The detection of the IR spectra features novel InGaAs detectors, specially developed for the SCIAMACHY project. While providing the required sensitivity in this wavelength domain, these detectors are limited by noise levels that vary strongly from pixel to pixel. This poses special challenges to the retrieval of molecule concentrations from the measured detector signals. Ways to overcome this problem are discussed.
Optical Remote Sensing of Atmospheric Aerosol Properties
Local aerosol concentrations and optical characteristics influenced by the Indonesian forest fire
Jianfei Ru,
Mitsuo Minomura,
Hiroaki Kuze,
et al.
Show abstract
Indonesian forest fire took place on Kalimantan and Sumatera islands in 1997 and continuously influenced the atmospheric conditions of South-East Asia nearly throughout the last half of that year. The color composed images of visible, near IR and IR channels from NOAA AVHRR daily data, arbitrarily assigned to red, green and blue respectively, were synthesized for distinguishing the smoke area. The data of three periods, the beginning, mid, and ending parts of the fire, were collected and analyzed in order to show the variation of atmosphere with the development of fire. A retrieval algorithm was established by use of Mie theory calculation and the radiative transfer code (MODTRAN 3). Local aerosol concentrations and properties over ocean parts between the two islands were derived. It is found that the aerosol optical thickness increased in accordance with the exacerbation of the fires. The changes of Ångstrom exponents show that smaller particle amounts were raised by the effects of burning.
Radiative Transfer Modeling and Retrieval Techniques
Microwindow optimization for atmospheric spectroscopy
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Microwindows are sets of consecutive gridpoints which are analyzed for retrieval of atmospheric state parameters rather than the spectrum as a whole. A good microwindow contains one or more prominent transitions of the target species. Interfering signal form non-target species shall be minimum. An objective and quantitative method is presented to optimally define microwindow boundaries such that retrieval errors are minimized.
Karlsruhe optimized and precise radiative transfer algorithm: III. ADDLIN and TRANSF algorithms for modeling spectral transmittance and radiance
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Two sets of subroutines for calculating absorption cross section spectra and transmission or radiance fields are presented. These libraries will be used in the operational data processing of the MIPAS/ENVISAT level-2 off-line processor and are part of the Karlruhe Optimized and Precise Radiative transfer Algorithm (KOPRA). The objective in developing these libraries was to accommodate flexibility and simplicity in use without substantial loss of accuracy and efficiency. The ADDLIN library uses an efficient method for calculating absorption cross section spectra line-by-line to arbitrary high numerical accuracy. Computational efficiency is achieved by calculating each spectral line on its own optimum set of sampling points. Absorption cross section spectra are stored on flexible, non-equidistant frequency grids. The TRANSF package provides integration routines that can be quickly configured for a variety of specific applications and measurement scenarios. The routines operate on the non-equidistant frequency grids produced by ADDIN and allow the researcher to implement the radiative transfer in a simple and almost natural way. Computational efficiency results from the reduced number of sampling points on the non-equidistant frequency grids produced by ADDIN and allow the researcher to implement the radiative transfer in a simple and almost natural way. Computational efficiency results from the reduced number of sampling points on the non-equidistant frequency grids compared to equidistant frequency grids of uniform intervals.
Karlsruhe optimized and precise radiative transfer algorithm: II. Interface to retrieval applications
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The new Karlsruhe Optimized and Precise Radiative transfer algorithm (KOPRA) is a line-by-line model for use in retrieval processors for atmospheric observations. It simulates IR spectra by taking into account physical properties of the atmospheric observations. It simulates IR spectra by taking into account physical properties of the atmosphere and of the instrument. Besides spectrum calculation, KOPRA has the capability to determine the derivatives of the spectrum with respect to many retrieval parameters. Comparisons between analytical and numerical derivatives, which are generally within a few percent, demonstrate that approximates due to run time optimized implementations are small. Furthermore, a flexible scheme is presented for handling various parameterizations of atmospheric profiles as implemented in the code in order to support different retrieval approaches.
Karlsruhe optimized and precise radiative transfer algorithm: I. Requirements, justification, and model error estimation
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We present the Karlsruhe Optimized and Precise Radiative transfer Algorithm (KOPRA) which has been specifically developed for data analysis of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) going to be launched on ESA's polar-orbiting Environmental Satellite 1 (ENVISAT-1) in 1999. KOPRA has been designed to account for the particular instrument requirements of MIPAS and the observation scenarii during the ENVISAT mission, in particular with respect to the viewing direction and the altitude coverage of the atmosphere. The conceptual details of KOPRA, which reflect the requirements set up by the instrument design details, the observation scenarii, and the link to a retrieval concept with high flexibility, are presented. The forward model error due to discarding individual physical processes and properties of the atmosphere as well as an over-all error budget with respect to these parameters is assessed in order to demonstrate the improvements of retrieval accuracy expected by usage of KOPRA.
Optical Remote Sensing of Atmospheric Aerosol Properties
Preliminary airborne lidar results in the Canadian Arctic during FIRE III
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Simultaneous upward/downward airborne lidar profiles were recently obtained in the Canadian Arctic during the First ISCCP Regional Experiment III. The lidar was mounted on board the National Research Council Canada Convair 580. Additional instrumentation aboard the CV580 included several particle sizing and imaging proves, liquid water content probes, a sensitive meteorological package and a chemistry package to measure particle speciation and bulk aerosol and gas phase properties. Within the four week period 18 flights were accomplished including 4 flights over the surface heat budget of the arctic ice camp. A depolarization channel was added to both the upward and downward lidar to help distinguish particle phase and sphericity. Preliminary lidar results from various ice crystal years, arctic haze layers, and boundary layer growth over open water will illustrate the uniqueness of this dataset. The lidar was also able to detect open leads and refrozen leads by examining the 'ground return' of both the polarized and depolarized channels.
Radiative Transfer Modeling and Retrieval Techniques
International ATOVS processing package: algorithm design and its preliminary performance
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The International ATOVS Processing Package (IAPP) is under development at the Cooperative Institute for Meteorological Satellite Studies, University of Wisconsin-Madison. The IAPP will be available to world wide users for processing real time ATOVS data. The retrieval algorithm of the IAPP is described with specific reference to retrieval of atmospheric temperature profile, moisture profile, total ozone, surface skin temperature, and microwave surface emissivity. Nine adjacent HIRS/3 spot observations together with the AMSU footprint remapped to the HIRS/3 resolution, are used to retrieve one atmospheric temperature profile and the other parameters within that domain. The algorithm is tested using simulated ATOVS data for both clear and cloudy sky conditions. Results demonstrate the potential use of IAPP for processing the real time ATOVS data.
Optical Remote Sensing of Surface and Cloud Properties
Geometric retrieval of cloud top height from MISR imagery
Jia Zong
Show abstract
The multi-stage imaging spectroradiometer (MISR) instrument, a part of NASA's the Earth Observing System (EOS), is to be launched in 1999 aboard the EOS AM-1 satellite. The MISR instrument consists of nine pushbroom cameras pointing at discrete view angles. Multi-angle imagery form MISR creates opportunities to retrieve new scientific parameters relating to the earth's aerosols, clouds, and surface. This paper focuses on the accurate geometric retrieval of cloud top height from MISR data. It consists of three major processing steps. The first process projects and registers multi-angle MISR radiance imagery to an ellipsoidal earth surface represented by the WGS-84 ellipsoid. The results of this processing provides not only surface registration but also near epipolar imaging geometry. The next processing step separates the cloud motion and cloud height. Traditionally, this has been considered a singular problem in photogrammetry even with stereo imagery. However, a separation condition does exist with satellite imaging and multiple MISR camera look-angles. The last processing step automatically retrieves cloud-top height field in high resolution from ellipsoid-projected MISR radiance imagery. This paper present the above three processing steps starting from an accurate and efficient projection of multi-angle MISR image data to the ellipsoid surface, followed by a mathematical derivation which separates the cloud motion and height, and finally an automatic image matching and ray intersection algorithm for high resolution cloud top height retrieval.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
Retrieval of total atmospheric ozone from GOES sounder radiance measurements with high spatial and temporal resolution
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The potential for using Geostationary Operational Environmental satellite (GOES) Sounder radiance measurements to monitor total atmospheric ozone is examined. A statistical regression using GOES channel 1 (4.7 μm), 2 (14.4 μm), 3 (14.1 μm), 4 (13.6 mu;m), and 9 (9.7 μm) radiances, followed by a physical iterative retrieval using only the channel 9 radiance, allows retrieval of total atmospheric ozone. Simulations show that the algorithm is suitable for retrieving total ozone with reasonable accuracy. At the conference, real GOES retrieved ozone values will be compared with total ozone mapping spectrometer ozone measurements from the Earth Probe satellite. Both qualitative and quantitative comparisons will show that the GOES retrievals are able to capture the main structure of the ozone distribution. Given the hourly measurements and high spatial density provided by the GOES Sounder, the potential use of GOES ozone retrievals and associated products is promising.
New Techniques, Instrument Calibration, and Data Validation
Optical balloon hygrometer for upper-troposphere and stratosphere water vapor measurements
Vladimir Yushkov,
Valery Astakhov,
Serafim Merkulov
Show abstract
An optical hygrometer has been upgraded to make night-time measurements of water vapor in the upper troposphere and stratosphere using the technique of photofragment fluorescence. Hygrometer uses the fluorescence at wavelength near 310 nm of excited OH molecules produced in the photodissociation of water molecules by UV radiation with hydrogen lamp. A coaxial optical scheme and photon counting mode are used. A compact hydrogen lamp is aligned along the axis of the instrument, inside the annular fast focusing optics. It provides the effective convergence of fluorescence from a large angle and thus increase the sensitivity of this method. Total weight of the optical hygrometer is about 2 kg. It can be easily integrated with the Vaisala RS-80 radiosonde. This allows to obtain reliable real-time data on temperature, pressure and water vapor concentration in the upper troposphere and stratosphere and conduct the validation of the remote sensing data.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
TOMS ozone data analysis of Indonesian forest fire effect on total ozone
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Biomass burning can result in tropospheric ozone increasing. In 1997, Indonesia big forest fire in dry season as a result of El Nino emitted large amounts of biomass burning plumes into the atmosphere, which produce ozone in troposphere via photochemical reaction. We mapped three day average of Earth Probe TOMS data from July to December 1997 in Latitude of 20 degrees S to 20 degrees N, and Longitude of 30 degrees E to 180 degrees E, which involves the forest fire area. As a composition we got every day ADEOS TOMS maps in the same area and the same period in 1996. From this maps we can find that in October 1997 the largest total amount of ozone was about 30 Dobson unit larger than the average in the same period of 1996. The area of largest amount was twice appeared in September 8 to 13 and October 11 to 19 which lasted about ten days. The location of that was in the west not far from the forest fire area which can be considered as a result of seasonal wind form east to west. Besides that a fairly large amount ozone area form east Indonesia through the west, we can find that ozone amount was largely increased than that of 1996.
ADEOS: Instruments, Data Processing, and Science
Latitudinal distribution of methane as observed by IMG sensor aboard ADEOS satellite
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Interferometric Monitor for Greenhouse gases aboard advanced earth observing satellite (ADEOS) is a Fourier transform type spectrometer which had been developed for measuring greenhouse gases in the atmosphere, particularly in the troposphere. It had been operated for about 7 months from November 1996 up to the end of the life time of the ADEOS on June 1997. During the operational period IMG had measured over 138000 terrestrial thermal emission spectra of which the signal to noise ratio is sufficient for retrieving atmospheric parameters such as temperature and gas concentrations. As most of the data had been obtained during the 4-days operational period which had been scheduled twice in each system request period, we have obtained about 15 global data sets of the IMG data during the whole IMG operational period. A cloud detection and correction method which was based on the analysis of the initially retrieved temperature profiles were presented. Using the cloud correction method, latitudinal distribution of methane was preliminary analyzed and an example of the result was shown.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
Method and instrument for the observation of the integral content of NO2 in the troposphere from an aircraft by reflected solar radiation
Eleonora A. Chayanova
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The integral content of NO2 in the troposphere layer below an aircraft flight level has been measured based on solar radiation reflected by the earth. These measurements were made using a spectrometer with a tunable interference-polarization filter in region 430-450 nm, looking at "nadir" from board an aircraft. There are short descriptions of the instrument, methodology an estimate errors. Results measurements compared with calculations by using models vertical distribution of NO2 in the troposphere. At the middle latitudes of the European and Asian parts of Russia the troposphere integral NO2 amount is 3.0•1016 - 3.2•1016 molec cm-2 during daytime in summer. In polar regions the troposphere integral NO2 amount during daytime in summer ranges within 1.0•1016 - 1.5•1016 molec cm-2, it can be attributed to the absence of ground sources there. A diurnal NO2 variation in the troposphere has been revealed which is inverse to that in the stratosphere. By sunset, NO2 content decreases nearly by a factor of 2. It has been detected that NO2 amount increases in the northern part of Western Siberia to range within 4.6•1016 - 5.8•1016 molec cm-2. This can be accounted for by the influence of industrial sources located in this region. Their effect is noticeable at distances up to 1000 km.
Radiative Transfer Modeling and Retrieval Techniques
Accuracy estimation of the SAGE-III retrieval algorithm for nitrogen dioxide, aerosol, and ozone
Eleonora A. Chayanova,
Yury A. Borisov
Show abstract
The procedure of nitrogen dioxide, aerosol and ozone vertical profile's inversion for the SAGE III transmission data in the spectral regions 430-450 nm, 560-616 nm and 290 nm is proposed. SAGE III instrument will measure slant path transmission function in range 430-450 nm at 20 spectral channels with 1 nm width, in range 560-616 nm at 5 spectral channels with 14 nm width. Nitrogen dioxide absorption has a quasi periodic structure in the first region that permits to separate a small extinction of this gas from a significant background of aerosol and Rayleigh extinction. For the separation of the total extinction into the compounds have been used retrieval algorithm both for each optical range individually and for all 26 wavelength conjointly. Second way use all information and lead to increase the retrieved profiles accuracy. For SAGE III data simulation, the forward calculation of the atmospheric transmission at 26 spectral channels for the tangent heights form 0 up to 80 km with 1 km step has been done. Transmission function in the calculations includes spherical refractive geometry, Rayleigh and aerosol scattering, and molecular absorption of the O3 and NO2 gases.
ADEOS: Instruments, Data Processing, and Science
Analysis of spectral radiance measurements by IMG on ADEOS
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The Interferometric Monitor for Greenhouse Gases (IMG) uses Fourier transform spectrometry to measure the top of the atmosphere spectral radiance between 3.3 μm and 14 μm in 3 separate bands. It was launched aboard the Japanese ADEOS satellite in August 1996, and has an unapodized spectral resolution of 0.05 cm-1. IMG spectral radiance measurements over different geographical spectral resolution of 0.05 cm-1. IMG spectral radiance measurements over different geographical regions are compared with standard line-by-line radiative transfer model calculations. CO retrieval and comparison between synthetic spectra calculated by FASCOD3 and IMG observations during the WINter Clouds Experiment (WINCE) are discussed as a case study. Preliminary analysis indicates that the retrieved CO from IMG spectral radiance measurements agrees with in-situ measurements made by the Climate Monitoring and Diagnostics Laboratory of the National Oceanic and Atmospheric Administration (NOAA/CMDL) at the nearby Park Falls monitoring site.
New Techniques, Instrument Calibration, and Data Validation
Remote sensing of tropospheric carbon monoxide amd methane from space by MOPITT: validation plan and prelaunch activities
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The measurement of pollution in the troposphere (MOPITT) is an eight-channel gas correlation radiometer to be launched on EOS/AM1 spacecraft in 1999. The goal of the experiment is to support studies of the oxidizing capacity of the lower atmosphere on large scales by measuring the global distributions of carbon monoxide (CO) and methane and thus, will represent a significant advancement in the application of space based remote sensing to global tropospheric chemistry research. Validation of data processing algorithms and products is an essential component of the MOPITT project. Strategies and techniques to verify MOPITT measurement precision, accuracy, and resolutions will be described. Correlative measurements for MOPITT algorithm and data validation include measurements will be described. Correlative measurements for MOPITT algorithm and data validation include measurements by airborne remote sensing and in-situ techniques and ground-based spectroscopic techniques. The MOPITT data processing algorithms are being tested and validated using existing airborne and satellite observations before launch. Pre-launch validation campaigns have been conducted to intercompare different correlative measurement techniques and associated data processing algorithms.
Optical Remote Sensing of Surface and Cloud Properties
Cloud parametrization for spaceborne lidar applications
Shiv R. Pal,
David P. Donovan,
J. P. Blanchet,
et al.
Show abstract
This paper discusses a cloud parameterization scheme for lidar application to cloud measurements by a space-borne lidar system. In lidar measurements generally the information on cloud particle size and number density is not available. Therefore, cloud parameterization becomes essential to derive from lidar observations the cloud optical parameters such as the extinction and backscatter coefficients and optical depth. In this study the lidar forward and retrieval models have been developed based on the lidar parameters for a conceived space-borne lidar system and applied to a derived cloud field which generates cloud definition parameters identical to the GCM-III. The lidar applicability to derive cloud physical and optical parameters has also been discussed.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Upper Atmosphere
Meteor-3M(1)/Stratospheric Aerosol and Gas Experiment III (SAGE III) jointly sponsored by the National Aeronautics and Space Administration and the Russian Space Agency
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The SAGE III is a joint Earth Observing System (EOS) mission between the US NASA and the Russian Space Agency (RSA) to fly aboard the Russian Meteor-3M(1) spacecraft to be launched from the Baikonur Cosmodrome in mid-1999. SAGE III is a spectrometer that measures attenuated radiation in the 282 nm to 1550 nm wavelength range which can be inverted to yield vertical profiles of ozone, aerosols and other species that are critical in studying trends and global change. In addition to SAGE III, the Meteor-3M(1) spacecraft carries nine Russian instruments for analyzing and forecasting environmental change and climate, for hydro-meteorological monitoring and for helio-geophysical research. Both the RSA and NASA are coordinating the activities associated with the joint mission development and implementation, including instrument development, spacecraft development, and mission operations.
Nitrogen dioxide monitoring with an automatic DOAS station at Terra Nova Bay, Antarctica
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During the last few years UV-Vis spectrometers were developed at the FISBAT Institute and are used for application of differential optical absorption spectroscopy method to detect many atmospheric trace gases playing important roles in the stratospheric chemistry. After several test both in laboratory and in Antarctic region, one of the spectrometers, called GASCOD2/2, was modified in collaboration with ENEA for unattended and automatic measurement in extreme high-latitude environment. The instrument was installed in December 1995 in the Italian Station at Terra Nova Bay. The aim of this research is to study the dentrification processes during the formation of the so-called ozone hole over the Antarctic region. The preliminary results for the first year of nitrogen dioxide measurement are presented and discussed.
Corrections for temperature dependence of the ring effect in DOAS measurements of stratospheric trace gases
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The present work deals with the problem regarding the improvement of the differential optical absorption spectroscopy (DOAS), applied to study the stratospheric ozone and other trace gases involved in this chemistry. In particular, the temperature dependence of the Ring effect and the related changes of the NO2 slant column caused by this dependence is verified. The temperature dependence of NO2 is also taken into account. It is shown that the stratospheric temperature variations of about +/- could modify the Stokes and anti-Stokes Raman component and hence modify the Ring effect. The presented results demonstrate that, if such temperature variations are ignored, the related NO2 slant column could be over- or underestimated of about 10 percent.
Radiative Transfer Modeling and Retrieval Techniques
Optimized forward and retrieval model for MIPAS near-real-time data processing
Show abstract
The IR emission limb sounder MIPAS will be operated as an ESA core instrument on the ENVISAT-1 satellite. Near real time retrieval of pressure, temperature and volume mixing ratio of five key species from calibrated spectra will be performed in the Level 2 processor of the ENVISAT Payload Data Segment. In order to develop an optimized retrieval algorithm suitable for the implementation in MIPAS Level 2 processor, an ESA supported study is being carried out. In the framework of this study, an optimized forward/retrieval code based on the global fit approach was implemented. In this approach all the spectra of a limb-scanning sequence are simultaneously fitted, so that error propagation in the altitude domain is avoided. The attained accuracy performances of the retrieval code are the following: (i) temperature accuracy < 2 K at all the altitudes covered by the standard MIPAS scan; (ii) tangent pressure error: < 3 percent; (iii) error on the retrieved VMR of the key species: < 5 percent at most of the latitudes of scientific interest covered by the standard MIPAS scan. The run-time required to perform p,T and VMR retrieval of the five MIPAS target species from a limb-scanning sequence of 16 limb-views is less than 6 minutes on a SUN SPARCstation 20. The most effective code optimization were implemented in the radiative transfer model and in the computation of the jacobian of the retrieval.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
Comparison of passive microwave sounding data with numerical weather prediction profiles
Stephen J. English,
Jeff K. Ridley,
Richard J. Renshaw,
et al.
Show abstract
The Advanced Microwave Sounding Unit (AMSU), launched on May 13, 1998, is a twenty-channel passive microwave radiometer designed to provide information on atmospheric temperature and humidity structure in clear and cloudy conditions, complementing existing infra-red radiometers which provide information only in clear areas. AMSU has some channels similar to those flown on existing missions and others which are new. Observed radiances from the Special Sensor
Microwave Imager (SSM/I) and the Microwave Sounding Unit (MSU) are compared with radiances calculated from numerical weather prediction (NWP) model profiles, and the differences discussed. A processing method for ATOVS radiances is described, and differences from previous techniques are highlighted. An initial evaluation of AMSU data is given. Finally the impact of passive microwave observations on the skill of numerical weather forecasts is discussed.
Global warming estimation from MSU
Cuddapah Prabhakara,
R. Iacovazzi Jr.,
J.-M. Yoo,
et al.
Show abstract
In this study, we develop an independent method to derive global temperature trend from Microwave Sounding Unit (MSU) radiometer observations in Ch 2 (53.74 GHz), made from sequential, sun-synchronous, polar-orbiting NOAA operational satellites. Also, a detailed examination of the systematic errors in these data is performed with the objective to improve this method. Partitioning these data from 75N to 75S into global land and ocean sets, and further subdividing them into am and pm subsets with the help of the LECT, enables us to perform this examination. The systematic errors in the MSU Ch 2 data are mainly related to differences in the MSU instrument calibration and the Local Equatorial Crossing Times (LECT) of successive satellites. They can be removed from these data with the help of the overlapping observations made by successive satellites. Errors in the MSU Ch 2 data are also introduced by orbital drift, which is the progressive change in the LECT of a satellite. Changes of the AM and PM observation times due to orbital drift causes Ch 2 brightness temperatures from each satellite to be affected by the diurnal cycle. In addition, orbital drift alters
satellite illumination by sun, and thereby the instrument alibration. These errors introduced by orbital drift cannot be eliminated objectively. However, in this study, the uncertainty in the global temperature trend resulting from the cumulative
error generated by drifts of all the satellites is inferred with an indirect approach. Based on our method of analysis of the MSU
Ch 2 data, we find a global temperature trend from 1980 to 1996 of 0.11 K decade-1 with an uncertainty of 0.06 K decade-1.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Upper Atmosphere
Advanced ground-based monitoring of stratospheric trace gas profiles: calibration, data analysis, and results
Gerd Hochschild,
Hermann Berg,
Gerhard Kopp,
et al.
Show abstract
The 268-280 GHz radiometer MIRA2 was constructed for ground-based monitoring of vertical profiles of minor stratospheric constituents and has been optimized especially for the observation of the extremely weak chlorine monoxide signature at 278 GHz and its diurnal variation. For calibration an adjustable internal load was developed, which provides any required brightness temperature from cryogenic to ambient temperatures, dependent on mechanical adjustment. In comparison to the well established external beam switching method this new technique results in a higher contrast in particular under critical conditions of the troposphere. For inversion of the measured spectra the modified Constrained Linear Inversion and the Optimal Estimation Method were used alternatively. The extensions of these well established methods include the fit of standing waves within the inversion process itself and the joint retrieval of several spectral lines. The advances in calibration and inversion techniques became obvious during the evaluation ofthe data measured at Kiruna, Sweden, 1996 and 1998, and Ny-Alesund, Svalbard, 1997. Profiles of the trace gases Ozone, N20, HNO3 and ClO could be retrieved. From the data measured in Ny-Alesund a unique time series of ClO- and Ozone has been achieved which shows diurnal and long term variations of ClO and Ozone, respectively.
Comparison of ozone profiles derived from ground-based microwave lidar measurements
Li Song,
Paul Hartogh,
Christopher Jarchow,
et al.
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A ground-based microwave heterodyne spectrometer for detection of middle atmospheric ozone has been developedmat Max-Planck-Institut für Aeronomie (MPAE), Germany. It was in operation from October 1995 until May 1996 atmthe Arctic Lidar Observatory for Middle Atmospheric Research (ALOMAR) near Andenes, Norway (69.3N, 16.0E). The microwave system provided ozone profiles in the altitude range from 15 to 80 km. During this period, a lidar system has been operated at the same location. The ozone profiles from the lidar covered the altitude range from 10 to 44 km. An intercomparison of 60 ozone profiles between the two instruments shows a good agreement. The mean microwave data were lower than the convolved mean lidar data by only 3% at 24 - 38km, and higher by only 5% at 20 — 24km. Above 38km the lidar measurements become more and more noise dominated, resulting in increasing errors and disagreement with the microwave measurements. The intercomparison suggests that the ozone profiles, provided by the microwave instrument, are not modulated by tropospheric transmission variations and that the other systematic error sources like residual baselines are properly modeled.
Joint Session With 3503: Optical and Microwave Remote Sensing of the Atmosphere--Lower Atmosphere
Experimental study of atmospheric boundary layer
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The Atmospheric Boundary Layer (ABL) is the most accessible layer of Earth's atmosphere. It is also the most important layer to the atmospheric research. We measure the wind arid turbulence profile in the ABL with a Doppler Sodar which can cover from 30m up to 300 500m, and a Boundary Microwave Wind Profiler, which can cover from 1OOm up to 3000m. With all these experimental sets, we can get the
continuous profiles of wind, refractive index structure function parameter, C2 and the wind structure function C2 from the ground up
to 3000m. From the results of these sets, we can obtain the characteristics of profiles and diurnal variations.
Radiative Transfer Modeling and Retrieval Techniques
Monitoring of total CO amount in the atmosphere using solar spectroscopy
Gengchen Wang,
Qinxin Kong,
Guangren Liu,
et al.
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Growing tendency of CO concentration in the atmosphere especially over city area, absorbs more and more attention from scientists and policy makers in many countries. CO, as a minor constituent and pollution gas in the atmosphere, plays an important role in the atmospheric chemistry processes in the troposphere. A ground-based spectroscopic method for determination of CO column amount in the atmosphere and some monitoring results in Beijing area are given and discussed in this paper.
Optical Remote Sensing of Surface and Cloud Properties
Principles and methodology for the geometrical parameter calculation of BRD
Xianhua Li,
Mingzhen Chen,
Genong Yu,
et al.
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This paper describes the principles and methodology to express and calculate bi-directional reflection (BDR) parameters of ground targets by using radioactively decomposed remotely sensed image under the support ofGIS and DTM. The principles and theoretical basis are that the difference of slope and its orientation changes the relative position of pixel ground, sun, and satellite sensor and results in the variety of solar direct radiance of similar pixels. The differences reflect the bi-directional reflectance. The bi-directional reflectance could be studied through the analysis of the difference and its relation with sun position and satellite position under the support of GIS and DTM, using direct radiance digital images. Topics, covered in this paper, include calculation geometrical parameters of BRDF, on both slopes and plains and for both satellite and sun.