Retrieved Optical Thickness for Analyzing The Aerosol and Cloud Properties Using Lidar Remote Sensing

The lidar remote sensing is the one important application to observe the aerosol and cloud of the atmosphere. Themicropulse lidar (MPL) return signals were studied in the tropical area. In this investigation, the single scatteringis analyzed by the physical properties of aerosol and cloud. The signal simulation of the single scattering predictsthe maximum optical thickness by saturation. It was observed that saturation optical thickness from the lidarsignal depends on the variation of extinction coefficient. This simulation is compared by the optical thicknessestimation from the lidar data. The MPL data (at wavelength of 523 nm) was determined, and the sky radiometer (atwavelength 500 nm) was used as reference data. The maximum optical thickness of lidar was 2.6 at night time,and the maximum optical depth of lidar and sky radiometer data on the same day were 2.25 and 1.7, respectively.

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Combined retrieval of Arctic liquid water cloud and surface snow properties using airborne spectral solar remote sensing

Atmospheric Measurement Techniques ◽

10.5194/amt-10-3215-2017 ◽

2017 ◽

Vol 10 (9) ◽

pp. 3215-3230 ◽

Cited By ~ 5

Author(s):

André Ehrlich ◽

Eike Bierwirth ◽

Larysa Istomina ◽

Manfred Wendisch

Keyword(s):

Remote Sensing ◽

Grain Size ◽

Sea Ice ◽

Optical Thickness ◽

Liquid Water ◽

Retrieval Algorithm ◽

Continuous Transition ◽

Cloud Properties ◽

Cloud Optical Thickness ◽

The Impact

Abstract. The passive solar remote sensing of cloud properties over highly reflecting ground is challenging, mostly due to the low contrast between the cloud reflectivity and that of the underlying surfaces (sea ice and snow). Uncertainties in the retrieved cloud optical thickness τ and cloud droplet effective radius reff, C may arise from uncertainties in the assumed spectral surface albedo, which is mainly determined by the generally unknown effective snow grain size reff, S. Therefore, in a first step the effects of the assumed snow grain size are systematically quantified for the conventional bispectral retrieval technique of τ and reff, C for liquid water clouds. In general, the impact of uncertainties of reff, S is largest for small snow grain sizes. While the uncertainties of retrieved τ are independent of the cloud optical thickness and solar zenith angle, the bias of retrieved reff, C increases for optically thin clouds and high Sun. The largest deviations between the retrieved and true original values are found with 83 % for τ and 62 % for reff, C. In the second part of the paper a retrieval method is presented that simultaneously derives all three parameters (τ, reff, C, reff, S) and therefore accounts for changes in the snow grain size. Ratios of spectral cloud reflectivity measurements at the three wavelengths λ1 = 1040 nm (sensitive to reff, S), λ2 = 1650 nm (sensitive to τ), and λ3 = 2100 nm (sensitive to reff, C) are combined in a trispectral retrieval algorithm. In a feasibility study, spectral cloud reflectivity measurements collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART) during the research campaign Vertical Distribution of Ice in Arctic Mixed-Phase Clouds (VERDI, April/May 2012) were used to test the retrieval procedure. Two cases of observations above the Canadian Beaufort Sea, one with dense snow-covered sea ice and another with a distinct snow-covered sea ice edge are analysed. The retrieved values of τ, reff, C, and reff, S show a continuous transition of cloud properties across snow-covered sea ice and open water and are consistent with estimates based on satellite data. It is shown that the uncertainties of the trispectral retrieval increase for high values of τ, and low reff, S but nevertheless allow the effective snow grain size in cloud-covered areas to be estimated.

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Investigation of ice particle habits to be used for ice cloud remote sensing for the GCOM-C satellite mission

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-12287-2016 ◽

2016 ◽

Vol 16 (18) ◽

pp. 12287-12303 ◽

Cited By ~ 32

Author(s):

Husi Letu ◽

Hiroshi Ishimoto ◽

Jerome Riedi ◽

Takashi Y. Nakajima ◽

Laurent C.-Labonnote ◽

...

Keyword(s):

Optical Thickness ◽

Single Scattering ◽

Single Scattering Albedo ◽

Asymmetry Factor ◽

Size Parameter ◽

Geometric Optics ◽

Ice Clouds ◽

Extinction Efficiency ◽

Ice Cloud ◽

Cloud Properties

Abstract. In this study, various ice particle habits are investigated in conjunction with inferring the optical properties of ice clouds for use in the Global Change Observation Mission-Climate (GCOM-C) satellite programme. We develop a database of the single-scattering properties of five ice habit models: plates, columns, droxtals, bullet rosettes, and Voronoi. The database is based on the specification of the Second Generation Global Imager (SGLI) sensor on board the GCOM-C satellite, which is scheduled to be launched in 2017 by the Japan Aerospace Exploration Agency. A combination of the finite-difference time-domain method, the geometric optics integral equation technique, and the geometric optics method is applied to compute the single-scattering properties of the selected ice particle habits at 36 wavelengths, from the visible to the infrared spectral regions. This covers the SGLI channels for the size parameter, which is defined as a single-particle radius of an equivalent volume sphere, ranging between 6 and 9000 µm. The database includes the extinction efficiency, absorption efficiency, average geometrical cross section, single-scattering albedo, asymmetry factor, size parameter of a volume-equivalent sphere, maximum distance from the centre of mass, particle volume, and six nonzero elements of the scattering phase matrix. The characteristics of calculated extinction efficiency, single-scattering albedo, and asymmetry factor of the five ice particle habits are compared. Furthermore, size-integrated bulk scattering properties for the five ice particle habit models are calculated from the single-scattering database and microphysical data. Using the five ice particle habit models, the optical thickness and spherical albedo of ice clouds are retrieved from the Polarization and Directionality of the Earth's Reflectances-3 (POLDER-3) measurements, recorded on board the Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar (PARASOL) satellite. The optimal ice particle habit for retrieving the SGLI ice cloud properties is investigated by adopting the spherical albedo difference (SAD) method. It is found that the SAD is distributed stably due to the scattering angle increases for bullet rosettes with an effective diameter (Deff) of 10 µm and Voronoi particles with Deff values of 10, 60, and 100 µm. It is confirmed that the SAD of small bullet-rosette particles and all sizes of Voronoi particles has a low angular dependence, indicating that a combination of the bullet-rosette and Voronoi models is sufficient for retrieval of the ice cloud's spherical albedo and optical thickness as effective habit models for the SGLI sensor. Finally, SAD analysis based on the Voronoi habit model with moderate particle size (Deff = 60 µm) is compared with the conventional general habit mixture model, inhomogeneous hexagonal monocrystal model, five-plate aggregate model, and ensemble ice particle model. The Voronoi habit model is found to have an effect similar to that found in some conventional models for the retrieval of ice cloud properties from space-borne radiometric observations.

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The effect of low-level thin arctic clouds on shortwave irradiance: evaluation of estimates from spaceborne passive imagery with aircraft observations

Atmospheric Measurement Techniques ◽

10.5194/amt-14-2673-2021 ◽

2021 ◽

Vol 14 (4) ◽

pp. 2673-2697

Author(s):

Hong Chen ◽

Sebastian Schmidt ◽

Michael D. King ◽

Galina Wind ◽

Anthony Bucholtz ◽

...

Keyword(s):

Remote Sensing ◽

Optical Thickness ◽

Surface Albedo ◽

The Arctic ◽

Cloud Detection ◽

Radiative Effects ◽

Study Region ◽

Airborne Measurements ◽

Low Level ◽

Cloud Properties

Abstract. Cloud optical properties such as optical thickness along with surface albedo are important inputs for deriving the shortwave radiative effects of clouds from spaceborne remote sensing. Owing to insufficient knowledge about the snow or ice surface in the Arctic, cloud detection and the retrieval products derived from passive remote sensing, such as from the Moderate Resolution Imaging Spectroradiometer (MODIS), are difficult to obtain with adequate accuracy – especially for low-level thin clouds, which are ubiquitous in the Arctic. This study aims at evaluating the spectral and broadband irradiance calculated from MODIS-derived cloud properties in the Arctic using aircraft measurements collected during the Arctic Radiation-IceBridge Sea and Ice Experiment (ARISE), specifically using the upwelling and downwelling shortwave spectral and broadband irradiance measured by the Solar Spectral Flux Radiometer (SSFR) and the BroadBand Radiometer system (BBR). This starts with the derivation of surface albedo from SSFR and BBR, accounting for the heterogeneous surface in the marginal ice zone (MIZ) with aircraft camera imagery, followed by subsequent intercomparisons of irradiance measurements and radiative transfer calculations in the presence of thin clouds. It ends with an attribution of any biases we found to causes, based on the spectral dependence and the variations in the measured and calculated irradiance along the flight track. The spectral surface albedo derived from the airborne radiometers is consistent with prior ground-based and airborne measurements and adequately represents the surface variability for the study region and time period. Somewhat surprisingly, the primary error in MODIS-derived irradiance fields for this study stems from undetected clouds, rather than from the retrieved cloud properties. In our case study, about 27 % of clouds remained undetected, which is attributable to clouds with an optical thickness of less than 0.5. We conclude that passive imagery has the potential to accurately predict shortwave irradiances in the region if the detection of thin clouds is improved. Of at least equal importance, however, is the need for an operational imagery-based surface albedo product for the polar regions that adequately captures its temporal, spatial, and spectral variability to estimate cloud radiative effects from spaceborne remote sensing.

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Investigation of ice particle habits to be used for ice cloud remote sensing for the GCOM-C satellite mission

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-31665-2015 ◽

2015 ◽

Vol 15 (21) ◽

pp. 31665-31703 ◽

Cited By ~ 2

Author(s):

H. Letu ◽

H. Ishimoto ◽

J. Riedi ◽

T. Y. Nakajima ◽

L. C.-Labonnote ◽

...

Keyword(s):

Optical Thickness ◽

Single Scattering ◽

Single Scattering Albedo ◽

Asymmetry Factor ◽

Particle Model ◽

Size Parameter ◽

Geometric Optics ◽

Extinction Efficiency ◽

Ice Cloud ◽

Cloud Properties

Abstract. Various ice particle habits are investigated in conjunction with inferring the optical properties of ice cloud for the Global Change Observation Mission-Climate (GCOM-C) satellite program. A database of the single-scattering properties of five ice particle habits, namely, plates, columns, droxtals, bullet-rosettes, and Voronoi, is developed. The database is based on the specification of the Second Generation Global Imager (SGLI) sensor onboard the GCOM-C satellite, which is scheduled to be launched in 2017 by Japan Aerospace Exploration Agency (JAXA). A combination of the finite-difference time-domain (FDTD) method, Geometric Optics Integral Equation (GOIE) technique, and geometric optics method (GOM) are applied to compute the single-scattering properties of the selected ice particle habits at 36 wavelengths, from the visible-to-infrared spectral region, covering the SGLI channels for the size parameter, which is defined with respect to the equivalent-volume radius sphere, which ranges between 6 and 9000. The database includes the extinction efficiency, absorption efficiency, average geometrical cross-section, single-scattering albedo, asymmetry factor, size parameter of an equivalent volume sphere, maximum distance from the center of mass, particle volume, and six non-zero elements of the scattering phase matrix. The characteristics of the calculated extinction efficiency, single-scattering albedo, and asymmetry factor of the five ice particle habits are compared. Furthermore, the optical thickness and spherical albedo of ice clouds using the five ice particle habit models are retrieved from the Polarization and Directionality of the Earth's Reflectances-3 (POLDER-3) measurements on board the Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar (PARASOL). The optimal ice particle habit for retrieving the SGLI ice cloud properties was investigated by adopting the spherical albedo difference (SAD) method. It is found that the SAD, for bullet-rosette particle, with radii of equivalent volume spheres (r~) ranging between 6 to 10 μm, and the Voronoi particle, with r~ ranging between 28 to 38 μm, and 70 to 100 μm, is distributed stably as the scattering angle increases. It is confirmed that the SAD of small bullet rosette and all sizes of voronoi particles has a low angular dependence, indicating that the combination of the bullet-rosette and Voronoi models are sufficient for retrieval of the ice cloud spherical albedo and optical thickness as an effective habit models of the SGLI sensor. Finally, SAD analysis based on the Voronoi habit model with moderate particles (r~ = 30 μm) is compared to the conventional General Habit Mixture (GHM), Inhomogeneous Hexagonal Monocrystal (IHM), 5-plate aggregate and ensemble ice particle model. It is confirmed that the Voronoi habit model has an effect similar to the counterparts of some conventional models on the retrieval of ice cloud properties from space-borne radiometric observations.

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Shortwave Radiative Effect of Arctic Low-Level Clouds: Evaluation of Imagery-Derived Irradiance with Aircraft Observations

10.5194/amt-2019-344 ◽

2019 ◽

Author(s):

Hong Chen ◽

Sebastian Schmidt ◽

Michael D. King ◽

Galina Wind ◽

Anthony Bucholtz ◽

...

Keyword(s):

Remote Sensing ◽

Optical Thickness ◽

Surface Albedo ◽

Detection Threshold ◽

The Arctic ◽

Radiative Effect ◽

Cloud Detection ◽

Study Region ◽

Low Level ◽

Cloud Properties

Abstract. Cloud optical properties such as optical thickness along with surface albedo are important inputs for deriving the shortwave radiative effects of clouds from space-borne remote sensing. Owing to insufficient knowledge about the snow or ice surface in the Arctic, cloud detection and the retrieval products derived from passive remote sensing, such as from the Moderate Resolution Imaging Spectroradiometer (MODIS), are difficult to obtain with adequate accuracy – especially for low-level thin clouds, which are ubiquitous in the Arctic. This study aims at evaluating the spectral and broadband irradiance calculated from MODIS-derived cloud properties in the Arctic using aircraft measurements collected during the Arctic Radiation-IceBridge Sea and Ice Experiment (ARISE), specifically using the upwelling and downwelling shortwave spectral and broadband irradiance measured by the Solar Spectral Flux Radiometer (SSFR) and the BroadBand Radiometer system (BBR). This entails the derivation of surface albedo from SSFR/BBR and camera imagery for heterogeneous surfaces in the marginal ice zone (MIZ), as well as subsequent measurement-model inter-comparisons in the presence of thin clouds. In addition to MODIS cloud retrievals and surface albedo from SSFR, we used temperature and humidity data from in-situ data and reanalysis (MERRA-2). The spectral surface albedo derived from the airborne radiometers is consistent with prior ground-based measurements, and adequately represents the surface variability for the study region and time period. Somewhat surprisingly, the primary error in MODIS-derived irradiance fields for this study stems from undetected clouds, rather than from the retrieved cloud properties. In our case studies, about 22 % of clouds remained undetected (cloud optical thickness less than 0.5). The radiative effect of clouds above the detection threshold was −40 W m−2 above cloud, and −39 W m−2 below the cloud layer, and the optical thickness from the MODIS "1621" cloud product was consistent with the reflected and transmitted irradiance observations. This study suggests that passive imagery cloud detection could be improved through a multi-pixel approach, that would make it more dependable in the Arctic. Regardless of the cloud retrieval method, there is a need for an operational imagery-based surface albedo product for the polar regions that adequately captures its temporal, spatial, and spectral variability to estimate cloud radiative effect from space-borne remote sensing.

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Night-Time Ground Hyperspectral Imaging for Urban-Scale Remote Sensing of Ambient PM. I. Aerosol Optical Thickness Acquisition

Aerosol Science and Technology ◽

10.1080/02786826.2012.700429 ◽

2012 ◽

Vol 46 (10) ◽

pp. 1119-1128 ◽

Cited By ~ 1

Author(s):

Yael Etzion ◽

Thomas Jarmer ◽

Tsafrir Kolatt ◽

Maxim Shoshany ◽

David M. Broday

Keyword(s):

Remote Sensing ◽

Hyperspectral Imaging ◽

Optical Thickness ◽

Aerosol Optical Thickness ◽

Night Time

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Temporal consistency of lidar observables during aerosol transport events in the framework of the ChArMEx/ADRIMED campaign at Menorca Island in June 2013

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-32723-2015 ◽

2015 ◽

Vol 15 (22) ◽

pp. 32723-32757 ◽

Cited By ~ 3

Author(s):

P. Chazette ◽

J. Totems ◽

G. Ancellet ◽

J. Pelon ◽

M. Sicard

Keyword(s):

Remote Sensing ◽

Biomass Burning ◽

Optical Thickness ◽

Forest Fires ◽

Extinction Ratio ◽

Aerosol Optical Thickness ◽

Dust Particles ◽

Temporal Consistency ◽

Night Time ◽

Observation Period

Abstract. We performed synergetic daytime and night-time active and passive remote sensing observations at Menorca (Balearic Island, Spain), over more than 3 weeks during the Chemistry–Aerosol Mediterranean Experiment/Aerosol Direct Radiative Effect in the Mediterranean (ChArMEx/ADRIMED) special observation period (SOP 1a, June–July 2013). We characterized the aerosol optical properties and type in the low and middle troposphere using an automated procedure combining Rayleigh–Mie–Raman lidar (355, 387 and 407 nm) with depolarization (355 nm) and AERONET Cimel® sun-photometer data. Results show a high variability due to varying dynamical forcing. The mean column-averaged lidar backscatter-to-extinction ratio (BER) was close to 0.024 sr-1 (lidar ratio of ∼ 41.7 sr), with a large dispersion of ±33 % over the whole observation period due to changing atmospheric transport regimes and aerosol sources. The ground-based remote sensing measurements, coupled with satellite observations, allowed to document (i) dust particles up to 5 km a.s.l. in altitude originating from Morocco and Algeria from 15 to 18 June with a peak in aerosol optical thickness (AOT) of 0.25 ± 0.05 at 355 nm, (ii) a long-range transport of biomass burning aerosol (AOT = 0.18 ± 0.16) related to North American forest fires detected from 26 to 28 June 2013 by the lidar between 2 and 7 km and (iii) mixture of local sources including marine aerosol particles and pollution from Spain. During the biomass burning event, the high value of the particle depolarization ratio (8–14 %) may imply the presence of dust-like particles mixed with the biomass burning aerosols in the mid troposphere. We show also linearity with SEVIRI retrievals of the aerosol optical thickness within 35 % relative bias, which is discussed as a function of aerosol type.

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Night-Time Light Remote Sensing Mapping: Construction and Analysis of Ethnic Minority Development Index

Remote Sensing ◽

10.3390/rs13112129 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2129

Author(s):

Fei Zhao ◽

Lu Song ◽

Zhiyan Peng ◽

Jianqin Yang ◽

Guize Luan ◽

...

Keyword(s):

Remote Sensing ◽

Ethnic Group ◽

Ethnic Groups ◽

Ethnic Minorities ◽

Population Data ◽

Night Time ◽

Entire Study ◽

Development Index ◽

Remote Sensing Mapping ◽

Entire Study Area

Using toponym data, population data, and night-time light data, we visualized the development index of the Yi, Wa, Zhuang, Naxi, Hani, and Dai ethnic groups on ArcGIS as well as the distribution of 25 ethnic minorities in the study area. First, we extracted the toponym data of 25 ethnic minorities in the study area, combined with night-time light data and the population proportion data of each ethnic group, then we obtained the development index of each ethnic group in the study area. We compared the development indexes of the Yi, Wa, Zhuang, Naxi, Hani, and Dai ethnic groups with higher development indexes. The results show that the Yi nationality’s development index was the highest, reaching 28.86 (with two decimal places), and the Dai nationality’s development index was the lowest (15.22). The areas with the highest minority development index were concentrated in the core area of the minority development, and the size varied with the minority’s distance. According to the distribution of ethnic minorities, we found that the Yi ethnic group was distributed in almost the entire study area, while other ethnic minorities had obvious geographical distribution characteristics, and there were multiple ethnic minorities living together. This research is of great significance to the cultural protection of ethnic minorities, the development of ethnic minorities, and the remote sensing mapping of lights at night.

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Remote sensing of water cloud droplet size distributions using the backscatter glory: a case study

Atmospheric Chemistry and Physics ◽

10.5194/acp-4-1255-2004 ◽

2004 ◽

Vol 4 (5) ◽

pp. 1255-1263 ◽

Cited By ~ 35

Author(s):

B. Mayer ◽

M. Schröder ◽

R. Preusker ◽

L. Schüller

Keyword(s):

Remote Sensing ◽

Size Distribution ◽

Droplet Size ◽

Cloud Droplet ◽

Droplet Size Distribution ◽

Single Scattering ◽

Effective Radius ◽

Radiative Properties ◽

High Angular Resolution ◽

Size Distributions

Abstract. Cloud single scattering properties are mainly determined by the effective radius of the droplet size distribution. There are only few exceptions where the shape of the size distribution affects the optical properties, in particular the rainbow and the glory directions of the scattering phase function. Using observations by the Compact Airborne Spectrographic Imager (CASI) in 180° backscatter geometry, we found that high angular resolution aircraft observations of the glory provide unique new information which is not available from traditional remote sensing techniques: Using only one single wavelength, 753nm, we were able to determine not only optical thickness and effective radius, but also the width of the size distribution at cloud top. Applying this novel technique to the ACE-2 CLOUDYCOLUMN experiment, we found that the size distributions were much narrower than usually assumed in radiation calculations which is in agreement with in-situ observations during this campaign. While the shape of the size distribution has only little relevance for the radiative properties of clouds, it is extremely important for understanding their formation and evolution.

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Mapping the Urban Atmospheric Carbon Stock by LiDAR and WorldView-3 Data

Forests ◽

10.3390/f12060692 ◽

2021 ◽

Vol 12 (6) ◽

pp. 692

Author(s):

MD Abdul Mueed Choudhury ◽

Ernesto Marcheggiani ◽

Andrea Galli ◽

Giuseppe Modica ◽

Ben Somers

Keyword(s):

Remote Sensing ◽

Urban Area ◽

Tree Species ◽

Carbon Stock ◽

Dominant Species ◽

Remote Sensing Data ◽

Data Sources ◽

Lidar Data ◽

Urban Tree ◽

Sensing Data

Currently, the worsening impacts of urbanizations have been impelled to the importance of monitoring and management of existing urban trees, securing sustainable use of the available green spaces. Urban tree species identification and evaluation of their roles in atmospheric Carbon Stock (CS) are still among the prime concerns for city planners regarding initiating a convenient and easily adaptive urban green planning and management system. A detailed methodology on the urban tree carbon stock calibration and mapping was conducted in the urban area of Brussels, Belgium. A comparative analysis of the mapping outcomes was assessed to define the convenience and efficiency of two different remote sensing data sources, Light Detection and Ranging (LiDAR) and WorldView-3 (WV-3), in a unique urban area. The mapping results were validated against field estimated carbon stocks. At the initial stage, dominant tree species were identified and classified using the high-resolution WorldView3 image, leading to the final carbon stock mapping based on the dominant species. An object-based image analysis approach was employed to attain an overall accuracy (OA) of 71% during the classification of the dominant species. The field estimations of carbon stock for each plot were done utilizing an allometric model based on the field tree dendrometric data. Later based on the correlation among the field data and the variables (i.e., Normalized Difference Vegetation Index, NDVI and Crown Height Model, CHM) extracted from the available remote sensing data, the carbon stock mapping and validation had been done in a GIS environment. The calibrated NDVI and CHM had been used to compute possible carbon stock in either case of the WV-3 image and LiDAR data, respectively. A comparative discussion has been introduced to bring out the issues, especially for the developing countries, where WV-3 data could be a better solution over the hardly available LiDAR data. This study could assist city planners in understanding and deciding the applicability of remote sensing data sources based on their availability and the level of expediency, ensuring a sustainable urban green management system.

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