For more than 15 years, NASA Langley Research Center (LaRC) has contributed in developing several 2-micron carbon dioxide active remote sensors using the DIAL technique. Currently, an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development at NASA LaRC. This paper focuses on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of wavelength control, packaging and lidar integration. In addition, receiver development updates will also be presented, including telescope integration, detection systems and data acquisition electronics. Future plan for IPDA lidar system for ground integration, testing and flight validation will be presented.

A 2-micron Ho:YLF laser end-pumped by 1.94-micron Tm:fiber laser was developed. A ring resonator oscillator of 3 m length and amplifier system was adopted. The laser was operated at high repetition rates of 200-5000 Hz in room temperature. The amplifier outputs were about 7.4W in CW and more than 6 Win Q-switch operation of repetition rates more than 500 Hz. This laser was developed to be used for coherent wind and CO2 measurements. Then, injection seeding was applied to the ring resonator and single mode laser emission was obtained. The laser was used for Doppler wind lidar measurements and wind profiles were obtained.

An airborne 2-m triple-pulse integrated path differential absorption (IPDA) lidar is currently under development at NASA Langley Research Center (LaRC). This IPDA lidar system targets both atmospheric carbon dioxide (CO₂) and water vapor (H₂O) column measurements. Independent wavelength control of each of the transmitted laser pulses is a key feature for the success of this instrument. The wavelength control unit provides switching, tuning and locking for each pulse in reference to a 2-μm CW laser source locked to CO₂ line-center. Targeting the CO₂ R30 line center, at 2050.967 nm, a wavelength locking unit has been integrated using semiconductor laser diode. The CO₂ center-line locking unit includes a laser diode current driver, temperature controller, center-line locking controller and CO₂ absorption cell. This paper presents the CO₂ center-line locking unit architecture, characterization procedure and results. Assessment of wavelength jitter on the IPDA measurement error will also be addressed by comparison to the system design.

Accurate measurements of forest biomass are important to evaluate its contribution to the global carbon cycle. Forest biomass correlates with forest canopy height; therefore, global measurements of canopy height enable a more precise understanding of the global carbon cycle. Space-borne lidar has the unique capability of measuring forest canopy height. A vegetation lidar named Multi-footprint Observation Lidar and Imager (MOLI) has been designed to make accurate measurements of canopy height and is currently being studied in the Japan Aerospace Exploration Agency. This papers introduces an overview of MOLI and its current status.

A long-lived UV laser is an enabling technology for a number of high-priority, space-based lidar instruments. These include next generation cloud and aerosol lidars that incorporates a UV channel, direct detection 3-D wind lidars, and ozone DIAL (differential absorption lidar) systems. In previous SBIR funded work we developed techniques for increasing the survivability of components in high power UV lasers and demonstrated improved operational lifetimes. In this Phase III ESTO funded effort we are designing and building a TRL (Technology Readiness Level) 6 demonstrator that will have increased output power and a space-qualifiable package that is mechanically robust and thermally-stable. For full space compatibility, thermal control will be through pure conductive cooling. Contamination control processes and optical coatings will be chosen that are compatible with lifetimes in excess of 1 billion shots. The 1064nm output will be frequency tripled to provide greater than 100 mJ pulses of 355 nm light at 150 Hz. The laser module build was completed in the third quarter of 2015 at which time a series of life tests were initiated. The first phase of the lifetime testing is a 532 nm only test that is expected to complete in April 2016. The 532 nm lifetest will be followed by a 4 month half power UV life test and then a four month full power UV life test. The lifetime tests will be followed by thermal/vacuum (TVAC) and vibration testing to demonstrate that the laser optics module design is at TRL 6.

Water vapour profiling of surface layer, which constitutes the lowest hundred meters from earth’s surface, can aid in the understanding of spatial variability of atmospheric turbulence and the dynamics of boundary layer. In lidars, the effective area of an optical fiber-based receiver, also called the aperture stop diameter, controls the field of view of the telescope which in turn governs the overlap function. We determined overlap function vs altitude for different aperture stop diameters which showed that lower altitude profiling requires fibre receivers of larger effective area positioned at the location of blur disk or the position of maximum capture of back scattered light. We report on the design of a receiver which comprises of a converging lens system in conjunction with a commercially available fibre bundle of fused hexagonal shaped fibres of adequate numerical aperture and enhanced effective light capturing area. For a specified biaxial Raman lidar system with an excitation laser emitting at 532 nm, placing a one inch diameter lens at the plane of blur disk of diameter ~21 mm and the aforesaid fibre bundle of diameter 7.3 mm at the image plane of the blur disk was found to be suitable for relatively efficient light capture to enable profiling from an altitude of ~8m and above. The light capturing efficiency of the system was determined and compared with that of a conventional circular fibre-based bundle of same diameter. The proposed receiver design offers potential solution for low altitude profiling with reduced central obscuration.

The clouds occur at high altitude have a significant impact on climate system. Much of the high altitude clouds generally occur in the tropical latitudes due to significant convective phenomena occurring in this region. These clouds occur in different forms such as anvil and stratus trails and sometimes not visible to satellite based instruments. The only means to detect this type of cloud in the atmosphere is using the Light Detection and Ranging (LIDAR) Technique. At National Atmospheric Research Laboratory (NARL), a Department of space unit located at Gadanki near Tirupati in Andhra Pradesh a portable LIDAR was developed and has been made operational since 2005. The LIDAR system employs 532nm wavelength Light Amplification by Stimulated Emission of Radiation (LASER) and used for monitoring the high altitude clouds during Nocturnal Periods. In this paper, the occurrence of high altitude clouds during the monsoon period has been detected using Ground based LIDAR. Using this synergical instrumentation data the occurrence, transport phenomena, optical properties and dynamism of high altitude clouds have been explained over tropical site Gadanki.

The present study describes Mie lidar observations of the cirrus cloud passage showing transition between double thin layers into single thick and single thick layer into double thin layers of cirrus over Gadanki region. During Case1: 17 January 2007, Case4: 12 June 2007, Case5: 14 July 2007 and Case6: 24 July 2007 the transition is found to from two thin cirrus layers into single geometrically thick layer. Case2: 14 May 2007 and Case3: 15 May 2007, the transition is found to from single geometrically thick layer into two thin cirrus layers. Linear Depolarization Ratio (LDR) and Back Scatter Ration (BSR) are found to show similar variation with strong peaks during transition; both LDR and Cloud Optical Depth (COD) is found to show similar variation except during transition with strong peaks in COD which is not clearly found from LDR for the all cases. There is a significant weakening of zonal and meridional winds during Case1 which might be due to the transition from multiple to single thick cirrus indicating potential capability of thick cirrus in modulating the wind fields. There exists strong upward wind dominance contributed to significant ascent in cloud-base altitude thereby causing transition of multiple thin layers into single thick cirrus.

In recent years weather modification activities are being pursued in many countries through cloud seeding techniques to facilitate the increased and timely precipitation from the clouds. In order to induce and accelerate the precipitation process clouds are artificially seeded with suitable materials like silver iodide, sodium chloride or other hygroscopic materials. The success of cloud seeding can be predicted with confidence if the precipitation process involving aerosol, the ice water balance, water vapor content and size of the seeding material in relation to aerosol in the cloud is monitored in real time and optimized. A project on the enhancement of rain fall through cloud seeding is being implemented jointly with Kerala State Electricity Board Ltd. Trivandrum, Kerala, India at the catchment areas of the reservoir of one of the Hydro electric projects. The dual polarization lidar is being used to monitor and measure the microphysical properties, the extinction coefficient, size distribution and related parameters of the clouds. The lidar makes use of the Mie, Rayleigh and Raman scattering techniques for the various measurement proposed. The measurements with the dual polarization lidar as above are being carried out in real time to obtain the various parameters during cloud seeding operations. In this paper we present the details of the multi-wavelength dual polarization lidar being used and the methodology to monitor the various cloud parameters involved in the precipitation process. The necessary retrieval algorithms for deriving the microphysical properties of clouds, aerosols characteristics and water vapor profiles are incorporated as a software package working under Lab-view for online and off line analysis. Details on the simulation studies and the theoretical model developed in this regard for the optimization of various parameters are discussed.

LIDAR (LIght Detection And Ranging) is an optical remote sensing technique which can be used to probe middle atmosphere (stratosphere & mesosphere) from where RADAR (RAdio Detection And Ranging) system fails to get scattering. The Mie and Rayleigh lidar system installed at National Atmospheric Research Laboratory (NARL), Gadanki (13.5°N, 79.2°E) has been operating at 532 nm green laser with increased energy of ~600 mJ/pulse and pulse repletion frequency of 50 Hz since 2007. From the Rayleigh lidar observations, vertical profiles of atmospheric density and temperature can be obtained above ~25-30 km (where the aerosols are almost negligible) at high spatial and temporal resolutions. The temperature profiles often show mesospheric inversion layers (MILs), the causative mechanisms of which are yet to be understood. In the present study, the improved performance of the lidar system is demonstrated by showing the height profile of temperature and its error obtained with the high power laser (~12 W per pulse) on 20 January 2007 when compared to the same obtained using the low power laser (~5 W per pulse) on 05 February 2007 over Gadanki. The temperature errors observed at ~80 km are ~3.5 K, ~18 K with high and low power lasers respectively. A large MIL has been observed on 20 January 2007 above ~78 km with amplitude of ~31 K from the lidar temperature operated with high power laser. The dominant gravity wave (GW) period and vertical wavelengths are found to be T~66 min and λ_z~6.4 km in the inversion region. The wave saturation ratio and eddy diffusion coefficient due to the GW breaking are calculated and it is found that the wave gets saturated at ~84-85 km and the eddy diffusion coefficient increases from ~25 m²/sec above the inversion region (~83 km). This result suggests that the occurrence of this large MIL event is probably due to gravity wave breaking.

Urban forest planning is important for providing better urban ecosystem services and conserve the natural carbon sinks inside the urban area. In this study, a demand based urban forest plan was developed for Chennai city by using Analytical Hierarchy Process (AHP) method. Population density, Tree cover, Air quality index and Carbon stocks are the parameters were considered in this study. Tree cover and Above Ground Biomass (AGB) layers were prepared at a resolution of 1m from airborne LiDAR and aerial photos. The ranks and weights are assigned by the spatial priority using AHP. The results show that, the actual status of the urban forest is not adequate to provide ecosystem services on spatial priority. From this perspective, we prepared a demand based plan for improving the urban ecosystem.

SAR and LiDAR remote sensing have already shown the potential of active sensors for forest parameter retrieval. SAR sensor in its fully polarimetric mode has an advantage to retrieve scattering property of different component of forest structure and LiDAR has the capability to measure structural information with very high accuracy. This study was focused on retrieval of forest aboveground biomass (AGB) using Terrestrial Laser Scanner (TLS) based point clouds and scattering property of forest vegetation obtained from decomposition modelling of RISAT-1 fully polarimetric SAR data. TLS data was acquired for 14 plots of Timli forest range, Uttarakhand, India. The forest area is dominated by Sal trees and random sampling with plot size of 0.1 ha (31.62m*31.62m) was adopted for TLS and field data collection. RISAT-1 data was processed to retrieve SAR data based variables and TLS point clouds based 3D imaging was done to retrieve LiDAR based variables. Surface scattering, double-bounce scattering, volume scattering, helix and wire scattering were the SAR based variables retrieved from polarimetric decomposition. Tree heights and stem diameters were used as LiDAR based variables retrieved from single tree vertical height and least square circle fit methods respectively. All the variables obtained for forest plots were used as an input in a machine learning based Random Forest Regression Model, which was developed in this study for forest AGB estimation. Modelled output for forest AGB showed reliable accuracy (RMSE = 27.68 t/ha) and a good coefficient of determination (0.63) was obtained through the linear regression between modelled AGB and field-estimated AGB. The sensitivity analysis showed that the model was more sensitive for the major contributed variables (stem diameter and volume scattering) and these variables were measured from two different remote sensing techniques. This study strongly recommends the integration of SAR and LiDAR data for forest AGB estimation.

Day night imaging application requires high dynamic range optical imaging system to detect targets of interest covering mid-day (>32000 Lux)^[1], and moonless night (∼1mLux)^[1] under clear sky- (visibility of >10km, atmospheric loss of <1dB/km) and hazy (visibility of >500m, atmospheric loss of >15dB/Km) conditions. Major governing factors for development of such camera systems are (i) covert imaging with ability to identify the target, (ii) imaging irrespective to the scene background, (iii) reliable operation , (iv) imaging capabilities in inclement weather conditions, (v) resource requirement vs availability power & mass, (vi) real-time data processing, (vii) self-calibration, and (viii) cost. Identification of optimum spectral band of interest is most important to meet these requirements. Conventional detection systems sensing in MWIR and LWIR band has certain draw backs in terms of target detection capabilities, susceptibility to background and huge thermo-mechanical resource requirement. Alternatively, range gated imaging camera system sensing in NIR/SWIR spectrum has shown significant potential to detect wide dynamic range targets. ToF Camera configured in NIR band has certain advantages in terms of Focal Plane Assembly (FPA) development with large format detectors and thermo-mechanical resource requirement compared to SWIR band camera configuration. In past, ToF camera systems were successfully configured in NIR spectrum using silicon based Electron Multiplying CCD (EMCCD), Intensifier CCD (ICCD) along with Gating device and pulsed laser source having emission in between 800nm to 900nm. However, these systems have a very low dynamic range and not suitable for clear sky mid-day conditions. Recently silicon based scientific grade CMOS image sensors have shown significant improvement in terms of high NIR responsivity and available in bigger formats (5MP or more), adequate Full well capacity for day time imaging (>30Ke), very low readout noise (<2e) required for night imaging and higher frame rate (more than 100fps). Taking advantage of these, laser based camera system configuration was worked out and presented in this paper using scientific grade CMOS sensor and NIR Laser. Camera can image target range from 4km to 5km with resolution of 5cm. Camera can have instantaneous coverage of 100mx100m (at 5km). Scientific grade CMOS sensor could also be used for clear sky day time imaging conditions with Laser off condition. To reduce the laser energy requirement, FPA required to be operated in multi-integration mode where multiple low energy pulses could be thrown within given integration time and detector and its associated electronics will collect and accumulate only those photons which are reflected back from the target of interest using appropriate gating control mechanism. Paper will bring out system engineering aspects for finalization of imaging spectrum, optical parameters in terms of aperture & focal length, required laser energy, highlighting advantage of pulse mode operation of laser compared to continuous mode operation in terms of laser energy & back-scattered light, silicon based optical detector performance results and post processing aspects for target detection. Paper will also discuss achieved performance of proto-model camera.

The National Atmospheric Research Laboratory (NARL), a unit of Department of Space (DOS), located at Gadanki village (13.5°N, 79.2°E, 370 m AMSL) in India, is involved in the development of lidar remote sensing technologies for atmospheric research. Several advanced lidar technologies employing micropulse, polarization, Raman and scanning have been developed at this site and demonstrated for atmospheric studies during the period between 2008 and 2015. The technology of micropulse lidar, operates at 532 nm wavelength, was successfully transferred to an industry and the commercial version has been identified for Indian Lidar network (I-LINK) programme. Under this lidar network activity, several lidar units were installed at different locations in India to study tropospheric aerosols and clouds. The polarization sensitive lidar technology was realized using a set of mini photomultiplier tube (PMT) units and has the capability to operate during day and night without a pause. The lidar technology uses a compact flashlamp pumped Qswitched laser and employs biaxial configuration between the transmitter and receiver units. The lidar technology has been utilized for understanding the polarization characteristics of boundary layer aerosols during the mixed layer development. The demonstrated Raman lidar technology, uses the third harmonic wavelength of Nd:YAG laser, provides the altitude profiles of aerosol backscattering, extinction and water vapor covering the boundary layer range and allows operation during nocturnal periods. The Raman lidar derived height profiles of aerosol backscattering and extinction coefficient, lidar ratio, and watervapor mixing ratio inform the tropical boundary layer aerosol characteristics. The scanning lidar technology uses a near infrared laser wavelength for probing the lower atmosphere and has been utilized for high resolution cloud profiling during convective periods. The lidar technology is also used for rain rate measurement during small scale rain periods over the tropical station, Gadanki. This paper describes the lidar technologies developed and observations conducted using the technologies demonstrated.

It is well established that atmospheric aerosol play a vital role both directly and indirectly in the Earth’s radiation budget. The transport of anthropogenic aerosol from the urban locations increases the aerosol loading in the surrounding semi-urban regions. The solid waste disposal in the semi-urban regions also adds up to the total anthropogenic aerosol density in the region. In this study we investigated the aerosol characteristics in the Cheeryal Village (17.51° N, 78.62° E), which is located at a distance of about 20 Km in the suburbs of Hyderabad, India. A multi-wavelength laser radar was developed in-house and made operational at this location about 2 years back. The Nd:YAG laser (M/S Bright Solutions, Italy) based multi-wavelength lidar operates at 532 nm and 1064 nm with a pulse energy of 50uJ at both the wavelengths. The two wavelengths are generated coaxially with a pulse width of 10ns and the laser operates up to a PRF of 4 KHz. The receiver system consists of a 360 mm Newtonian optical telescope, 10 nm of interference filters and the Licel Gmbh, Germany make 250 MHz Photon Counting recorder. Lidar observations are conducted on relatively clear days during the one year period from January 2014 to December 2014. The aerosol extinction profiles are derived and compared with the model values corresponding to the Hyderabad urban region. It is observed that there is a heavy aerosol loading periodically at this location in relation to the sources of anthropogenic aerosols at Hyderabad urban area. The role of prevailing meteorological conditions, measured in real time, on the transport of the urban aerosol to this region is studied.

A single channel elastic-backscatter lidar system was developed in-house at National Atmospheric Research Laboratory, an institution under Department of Space and Government of India, for studies on boundary layer dynamics during convective periods. The developed lidar system operates at the second harmonic wavelength of Nd: YAG laser and uses biaxial configuration. The lidar system utilizes a mini PMT for detecting laser returns from the atmosphere and operates in the analogue mode of data acquisition. The analogue recorder operates at 20 MHz sampling and uses a 12 bit A to D converter. The lidar system capable to operate at a maximum vertical resolution 7.5 m and 1-sec time sampling. However, in the present study, the lidar was operated with 30 m vertical resolution and 30-sec time sampling to understand the boundary layer dynamics during convective periods. The lidar measurements conducted between January and March 2014 were used in the present study. The laser backscatters obtained at 532 nm wavelength were corrected for noise and range before application of above mentioned analytical methods.

This study presents evaluation of mixed layer height (MLH) from lidar using different analytical methods such as gradient, variance and wavelet techniques and presentation of inter-comparison between methods to achieve suitable method for assessment of MLH. The estimated MLH is then compared with the simultaneous radiosonde observations and empirical model values. We computed the MLH growth rates and observed that a significant enhancement was seen during the transition from winter to pre-monsoon period which could be attributed to increased convective activity over the tropical site. We present the lidar measurements and discuss the MLH retrieval and growth rates over Gadanki using lidar measurements.

High-resolution dual polarized micropulse lidar (MPL) observations have been used to investigate the diurnal evolution of atmospheric boundary layer (ABL) during winter (2008–2011) over Thiruvananthapuram (8.5°N, 77°E), a tropical coastal station located at southwest Peninsular India, adjoining the Arabian Sea. The lidar observations are compared with the boundary layer characteristics derived from concurrent balloon-borne radiosonde observations. This study shows that the mixed layer height over this coastal station generally increases from <300 m in the morning to ∼1500 m by the afternoon. Growth rate of the mixed layer height is rapid (∼350 m/hr) during 09–11 IST and slows down with time to <150 m/hr during 11–14 IST and <90 m/hr during 14–16 IST. Thermal internal boundary layer during the afternoon, caused by sea breeze circulation, extends up to ∼500 m altitude and is characterized by highly spherical aerosols, while a distinctly non-spherical aerosol layer appear above this altitude, in the return flow arising from the landmass.

This paper describes the measurements carried out on shape and size information of boundary layer aerosol particles using a lidar system developed at NARL, Gadanki. The lidar system profiles the boundary layer at 1064 and 532 nm wavelengths, which are fundamental and second harmonic components of Nd:YAG laser. However, the polarization measurements are conducted at 532 nm only. Using an external dichroic mirror in the laser path, the Nd:YAG laser output is separated into its harmonics. The fundamental harmonic of Nd:YAG laser is steered into atmosphere using a hard coated mirror and the atmospheric returns at 1064 and 532 nm are collected using two independent telescopes. The laser backscatter corresponding to 1064 nm is detected using an Avalanche photodiode; whereas the co and cross polarized signals returns corresponding to 532 nm laser are detected using a set of mini-PMT units. A three channel transient recorder unit is employed for recording the signals utilizing the analog and photon counting electronics. The lidar system is possible to operate in daylight period and can provide information on scattering properties of boundary layer aerosols.

In the present study, measurements during long range transport events were performed at NARL, Gadanki during the year 2012. We proposed to present two case studies on long range transport that occurred during the year 2012. We present the results in terms of aerosol backscattering coefficient, depolarization ratio and color ratio with support of back trajectory analysis.

In this paper we focus on the estimation of the Signal-to-Noise (SNR) ratio of a 3-channel commercial (Raymetics) volcanic ash detection system, (LR111-D300), already operating in UK, and also, we perform a basic lidar polarization sensitivity analysis. The results show that SNR values are higher than 10 for ranges up to 13 km for daytime conditions. This is a quite good result compared with other values presented in bibliography and prove that such system is able to detect volcanic ash detection over a range of 20 km. We also assess the lidar polarization sensitivity and then, we estimate the linear depolarization ratio. By careful choice of the optical components (emitting and receiving optics), it has been shown that uncertainties of polarization states at receiver (and thus too depolarization ratio estimation) can be much reduced.

Continuous monitoring of aerosol profiles using lidar is helpful for a quasi-real-time indication of aerosol concentration. For instance, volcanic ash concentration and its height distribution are essential information for plane flights. Depolarization ratio and multi-wavelength measurements are useful for characterizing aerosol types such as volcanic ash, smoke, dust, sea-salt, and air pollution aerosols. High spectral resolution lidar (HSRL) and Raman scattering lidar can contribute to such aerosol characterization significantly since extinction coefficients can be measured independently from backscattering coefficients. In particular, HSRL can measure aerosol extinction during daytime and nighttime with a high sensitivity. We developed an HSRL with the iodine filter method for continuous observation of aerosols at 532nm in the northern region of Argentina in the framework of the South American Environmental Atmospheric Risk Management Network (SAVER.Net)/SATREPS project. The laser wavelength of the HSRL was controlled by a feedback system to tune the laser wavelength to the center of an iodine absorption line. The stability of the laser wavelength with the system satisfied the requirement showing very small systematic errors in the retrieval of extinction and backscatter.

There is growing interest in development of electro-optical systems capable of operation over long atmospheric distances in various atmospheric conditions. Some of these systems include laser communications, remote sensing, active and passive imaging, target tracking and designation and laser beam projection (directed energy) systems. As increasingly sophisticated electro-optical systems are used in the atmosphere, the character of the medium becomes important. Optical turbulence is one of the most important characteristics for propagation through the atmosphere. A single ended experimental setup using the Nd: YAG laser operating at 1064nm is used to study the temporal and spatial variations of refractive index structure parameter C_n² experimentally. In this paper we present the details of the experimental setup used for the measurement of range resolved refractive index structure parameter C_n², over a two way slant 4.0 km free space laser path. Some of the results obtained using the experimental setup are presented and discussed.

Applicability of a KTA crystal-based laser system with optical parametric oscillators (OPO) generation to lidar sounding of the atmosphere in the spectral range 3–4 μm is studied in this work. A technique developed for lidar sounding of trace atmospheric gases (TAG) is based on differential absorption lidar (DIAL) method and differential optical absorption spectroscopy (DOAS). The new technique uses broadband radiation and a CCD detector, which ensures measurement of backscattering signals with simultaneous altitude and wavelength resolution. The DIAL-DOAS technique is tested to estimate its efficiency for lidar sounding of atmospheric trace gases. The numerical simulation performed shows that a KTA-based OPO laser is a promising source of radiation for remote DIAL-DOAS sounding of the TAGs under study along surface tropospheric paths. The laser system design provides a possibility of narrowing the laser line within the 0.01–5 cm^-1 limits. This possible improvement along with a small step of laser line tuning and the presence of absorption lines of other atmospheric gases, including atmospheric pollutants, in the spectral range under study make this laser a unique instrument for atmospheric sounding.

Airborne LiDAR is fast becoming an innovation for forest inventory. It aids in obtaining forest characteristics in areas or cases where actual field inventory would be very tedious. This study aims to estimate diameter at breast height (DBH) using airborne LiDAR point-cloud parameters with Worldview-2 satellite images, and to validate these with actual measurements done in the field. The study site is a field plot with forest inventory at Mt. Makiling, Laguna, Philippines that was surveyed into 20m, 10m and 5m subplots or grids. The estimation of DBH was carried out by extracting the said parameters from the LiDAR point-cloud, and extracting different bands from the Worldview image and performing linear and log-linear regression of these values. The regressions were done in four different cases, namely: LiDAR parameters without intensity (case1), LiDAR parameters without intensity with Worldview bands (case 2), intensity of LiDAR points (case 3), and LiDAR parameters with intensity and Worldview bands (case 4). From these it was found that the best case for estimating DBH is with the use of LiDAR parameters with intensity and Worldview bands in a 10x10 grid, in Log-Linear regression with a root mean squared error of 1.96 cm and an adjusted R² value of 0.65. This was further improved through stepwise regression, and adjusted R² value was 0.71.

LiDAR Overlap is the area that is common to two or more flight lines. This is essential to ensure the continuity of data as the acquisition moves from one flight line to another. Looking into overlaps is important when doing DBH Estimation using point cloud data because it doubles the density of points in the overlap region. To remove this effect when determining the DBH of a forest area, the LiDAR data was processed using a point-cloud processing software. The processes include separating flight lines using the GPS time when the points were acquired. After separating, the number of points in the overlap region were decreased by removing excess points within the area of twice the point spacing. The parameters needed for DBH estimation were then obtained. The absolute number of points in the whole overlap area was originally 4,960,726 after decreasing the number of points, it was reduced to 1,479,884. The number of points would have an effect on DBH estimation because the values obtained were significantly different at 95% level of confidence.

The extent at which mangrove forest characterization can be done through utilization of Light Detection and Ranging (LiDAR) data is investigated in this paper. Particularly, the ability of LiDAR parameters, such as its point density to provide height and structural information was explored to supplement manual field surveys which are time-consuming and requires great effort. Point cloud information was used to produce separability measure within a mangrove forest. The study aims to validate the point density distribution curves (PDDC) that were established to characterize the structural attributes between Rhizophoraceae and Avicenniaceae. The applicability of the PDDC was applied to fifteen (15) 5x5 sample plots of pure Rhizophoraceae and fifteen (15) 5x5 sample plots of pure Avicenniaceae in a one hectare (1ha) natural riverine mangrove forest. 15 out of 15 plots were correctly discriminated as Rhizophoraceae; however, Avicenniaceae plots were not correctly discriminated using the established separability measure. This study had determined that the two mangrove families are difficult to separate in terms of point density distribution alone. Enhancement of the PDDC as a separability measure should be improved to pave way for a more sensitive and robust way to separate the two families.

The paper introduces the technique of recovering profiles of ozone vertical distribution considering temperature and aerosol correction in atmosphere lidar sounding by DIAL. The authors have determined wavelengths, promising to measure ozone profiles in the upper troposphere — lower stratosphere. To obtain promptly the results of the methodology the authors developed the software based on DIAL with user-friendly interface in the programming language C# using the lidar measurements. The recovered ozone profiles, resulting from the program operation, were compared with IASI satellite data and Kruger model. The results of applying the developed technique to recover the profiles of ozone vertical distribution considering temperature and aerosol correction in the altitude range of 6–18 km in lidar atmosphere sounding by DIAL confirm the prospects of using the selected wavelengths of ozone sensing 341 and 299 nm in the ozone lidar.

Atmospheric monitoring stations are being developed in Argentina. The most important targets are volcanic ashes, desert aerosols in particular Patagonian dust and biomass burning aerosols. Six stations deployed in the Patagonian Region and Buenos Aires have lidar systems, sun photometers integrated to the AERONET/NASA monitoring network, in situ optical particle analyzers, four solar radiation sensors (pyranometer, UVA, UVB and GUV), and meteorological equipment. The stations are in the main international airports of the Regions (San Carlos de Bariloche, Comodoro Rivadavia, Neuquén, Rio Gallegos) and in Buenos Aires (Aeroparque Jorge Newbery and at CEILAP/CITEDEF). CEILAP and the National Institute of Environmental Studies (NIES) at Tsukuba, Japan developed the first iodine cell-based high spectral resolution lidar (HSRL) in Argentina to add in the lidar network. We upgraded the standard CEILAP multi-wavelength Raman lidar adding the laser frequency tuning system and the 532 iodine-filtered channel at the reception to built the HSRL. HSRL will provide daytime and nighttime direct observation of the aerosol and cloud optical properties (backscatter and extinction) without the pre-assumption of the lidar ratio. This work shows the design and construction of the first Argentinean HSRL. We also show the first lidar observations done in the country with this kind of lidar.