Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin
We have compared the spectral aerosol optical depth (AOD, τλ) and aerosol fine mode fraction (AFMF) of Collection 004 (C004) derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) on board National Aeronautics and Space Administration's (NASA) Terra and Aqua platforms with that obta...
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ftindianacasci:oai:repository.ias.ac.in:69286 2023-05-15T13:06:38+02:00 Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin Jethva, Hiren Satheesh, S. K. Srinivasan, J. 2007 http://repository.ias.ac.in/69286/ http://www.agu.org/journals/ABS/2007/2006JD007929.shtml unknown American Geophysical Union Jethva, Hiren Satheesh, S. K. Srinivasan, J. (2007) Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin Journal of Geophysical Research - D: Atmospheres, 112 . D14216_1-D14216_9. ISSN 0148-0227 QE Geology Article PeerReviewed 2007 ftindianacasci 2013-01-20T12:39:34Z We have compared the spectral aerosol optical depth (AOD, τλ) and aerosol fine mode fraction (AFMF) of Collection 004 (C004) derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) on board National Aeronautics and Space Administration's (NASA) Terra and Aqua platforms with that obtained from Aerosol Robotic Network (AERONET) at Kanpur (26.45°N, 80.35°E), India for the period 2001–2005. The spatially-averaged (0.5° × 0.5° centered at AERONET sunphotometer) MODIS Level-2 aerosol parameters (10 km at nadir) were compared with the temporally averaged AERONET-measured AOD (within ± 30 minutes of MODIS overpass). We found that MODIS systematically overestimated AOD during the pre-monsoon season (March to June, known to be influenced by dust aerosols). The errors in AOD at 0.66 μm were correlated with the apparent reflectance at 2.1 μm (ρ* 2.1 ) which MODIS C004 uses to estimate the surface reflectance in the visible channels (ρ 0.47 = ρ* 2.1 /4, ρ 0.66 = ρ* 2.1 /2). The large errors in AOD (Δτ 0.66 > 0.3) are found to be associated with the higher values of ρ* 2.1 (0.18 to 0.25), where the uncertainty in the ratios of reflectance is large (Δρ 0.66 ± 0.04, Δρ 0.47 ± 0.02). This could have resulted in lower surface reflectance, higher aerosol path radiance and thus lead to overestimation in AOD. While MODIS-derived AFMF has binary distribution (1 or 0) with too low (AFMF < 0.2) during dust-loading period, and ∼1 for the rest of the retrievals, AERONET showed range of values (0.4 to 0.9). The errors in τ 0.66 were also high in the scattering angle range 110°–140°, where the optical effects of nonspherical dust particles are different from that of spherical particles. Article in Journal/Newspaper Aerosol Robotic Network Indian Academy of Sciences: Publication of Fellows |
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Indian Academy of Sciences: Publication of Fellows |
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QE Geology |
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QE Geology Jethva, Hiren Satheesh, S. K. Srinivasan, J. Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin |
topic_facet |
QE Geology |
description |
We have compared the spectral aerosol optical depth (AOD, τλ) and aerosol fine mode fraction (AFMF) of Collection 004 (C004) derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) on board National Aeronautics and Space Administration's (NASA) Terra and Aqua platforms with that obtained from Aerosol Robotic Network (AERONET) at Kanpur (26.45°N, 80.35°E), India for the period 2001–2005. The spatially-averaged (0.5° × 0.5° centered at AERONET sunphotometer) MODIS Level-2 aerosol parameters (10 km at nadir) were compared with the temporally averaged AERONET-measured AOD (within ± 30 minutes of MODIS overpass). We found that MODIS systematically overestimated AOD during the pre-monsoon season (March to June, known to be influenced by dust aerosols). The errors in AOD at 0.66 μm were correlated with the apparent reflectance at 2.1 μm (ρ* 2.1 ) which MODIS C004 uses to estimate the surface reflectance in the visible channels (ρ 0.47 = ρ* 2.1 /4, ρ 0.66 = ρ* 2.1 /2). The large errors in AOD (Δτ 0.66 > 0.3) are found to be associated with the higher values of ρ* 2.1 (0.18 to 0.25), where the uncertainty in the ratios of reflectance is large (Δρ 0.66 ± 0.04, Δρ 0.47 ± 0.02). This could have resulted in lower surface reflectance, higher aerosol path radiance and thus lead to overestimation in AOD. While MODIS-derived AFMF has binary distribution (1 or 0) with too low (AFMF < 0.2) during dust-loading period, and ∼1 for the rest of the retrievals, AERONET showed range of values (0.4 to 0.9). The errors in τ 0.66 were also high in the scattering angle range 110°–140°, where the optical effects of nonspherical dust particles are different from that of spherical particles. |
format |
Article in Journal/Newspaper |
author |
Jethva, Hiren Satheesh, S. K. Srinivasan, J. |
author_facet |
Jethva, Hiren Satheesh, S. K. Srinivasan, J. |
author_sort |
Jethva, Hiren |
title |
Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin |
title_short |
Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin |
title_full |
Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin |
title_fullStr |
Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin |
title_full_unstemmed |
Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin |
title_sort |
evaluation of moderate-resolution imaging spectroradiometer (modis) collection 004 (c004) aerosol retrievals at kanpur, indo-gangetic basin |
publisher |
American Geophysical Union |
publishDate |
2007 |
url |
http://repository.ias.ac.in/69286/ http://www.agu.org/journals/ABS/2007/2006JD007929.shtml |
genre |
Aerosol Robotic Network |
genre_facet |
Aerosol Robotic Network |
op_relation |
Jethva, Hiren Satheesh, S. K. Srinivasan, J. (2007) Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin Journal of Geophysical Research - D: Atmospheres, 112 . D14216_1-D14216_9. ISSN 0148-0227 |
_version_ |
1766014263922524160 |