Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic basin
[1] We have compared the spectral aerosol optical depth (AOD, tau lambda) 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 wi...
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American Geophysical Union
2007
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ftiiscindia:oai:eprints.iisc.ernet.in:26213 2023-05-15T13:06:59+02:00 Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic basin Jethva, Hiren Satheesh, SK Srinivasan, J 2007-07-31 http://eprints.iisc.ernet.in/26213/ http://www.agu.org/pubs/crossref/2007/2006JD007929.shtml unknown American Geophysical Union Jethva, Hiren and Satheesh, SK and Srinivasan, J (2007) Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic basin. In: Journal of Geophysihttp://eprints.iisc.ernet.in/cgi/users/home?screen=EPrint::Edit&eprintid=26213&stage=core#tcal Research, 112 (D14216). p. 9. Centre for Atmospheric & Oceanic Sciences Journal Article PeerReviewed 2007 ftiiscindia 2014-09-27T17:47:19Z [1] We have compared the spectral aerosol optical depth (AOD, tau lambda) 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 degrees N, 80.35 degrees E), India for the period 2001-2005. The spatially-averaged (0.5 degrees x 0.5 degrees 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 mu m were correlated with the apparent reflectance at 2.1 mu m (rho*(2.1)) which MODIS C004 uses to estimate the surface reflectance in the visible channels (rho(0.47) = rho*(2.1)/ 4, rho(0.66) = rho*(2.1)/ 2). The large errors in AOD (Delta tau(0.66) > 0.3) are found to be associated with the higher values of rho*(2.1) (0.18 to 0.25), where the uncertainty in the ratios of reflectance is large (Delta rho(0.66) +/- 0.04, Delta rho(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 similar to 1 for the rest of the retrievals, AERONET showed range of values (0.4 to 0.9). The errors in tau(0.66) were also high in the scattering angle range 110 degrees - 140 degrees, where the optical effects of nonspherical dust particles are different from that of spherical particles. Article in Journal/Newspaper Aerosol Robotic Network Indian Institute of Science, Bangalore: ePrints@IIsc Lambda ENVELOPE(-62.983,-62.983,-64.300,-64.300) Rho ENVELOPE(-63.000,-63.000,-64.300,-64.300) |
institution |
Open Polar |
collection |
Indian Institute of Science, Bangalore: ePrints@IIsc |
op_collection_id |
ftiiscindia |
language |
unknown |
topic |
Centre for Atmospheric & Oceanic Sciences |
spellingShingle |
Centre for Atmospheric & Oceanic Sciences Jethva, Hiren Satheesh, SK Srinivasan, J Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic basin |
topic_facet |
Centre for Atmospheric & Oceanic Sciences |
description |
[1] We have compared the spectral aerosol optical depth (AOD, tau lambda) 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 degrees N, 80.35 degrees E), India for the period 2001-2005. The spatially-averaged (0.5 degrees x 0.5 degrees 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 mu m were correlated with the apparent reflectance at 2.1 mu m (rho*(2.1)) which MODIS C004 uses to estimate the surface reflectance in the visible channels (rho(0.47) = rho*(2.1)/ 4, rho(0.66) = rho*(2.1)/ 2). The large errors in AOD (Delta tau(0.66) > 0.3) are found to be associated with the higher values of rho*(2.1) (0.18 to 0.25), where the uncertainty in the ratios of reflectance is large (Delta rho(0.66) +/- 0.04, Delta rho(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 similar to 1 for the rest of the retrievals, AERONET showed range of values (0.4 to 0.9). The errors in tau(0.66) were also high in the scattering angle range 110 degrees - 140 degrees, where the optical effects of nonspherical dust particles are different from that of spherical particles. |
format |
Article in Journal/Newspaper |
author |
Jethva, Hiren Satheesh, SK Srinivasan, J |
author_facet |
Jethva, Hiren Satheesh, SK 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://eprints.iisc.ernet.in/26213/ http://www.agu.org/pubs/crossref/2007/2006JD007929.shtml |
long_lat |
ENVELOPE(-62.983,-62.983,-64.300,-64.300) ENVELOPE(-63.000,-63.000,-64.300,-64.300) |
geographic |
Lambda Rho |
geographic_facet |
Lambda Rho |
genre |
Aerosol Robotic Network |
genre_facet |
Aerosol Robotic Network |
op_relation |
Jethva, Hiren and Satheesh, SK and Srinivasan, J (2007) Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic basin. In: Journal of Geophysihttp://eprints.iisc.ernet.in/cgi/users/home?screen=EPrint::Edit&eprintid=26213&stage=core#tcal Research, 112 (D14216). p. 9. |
_version_ |
1766029669781471232 |