Impact of Aerosol Vertical Distribution on Aerosol Optical Depth Retrieval from Passive Satellite Sensors
When retrieving Aerosol Optical Depth (AOD) from passive satellite sensors, the vertical distribution of aerosols usually needs to be assumed, potentially causing uncertainties in the retrievals. In this study, we use the Moderate Resolution Spectroradiometer (MODIS) and Visible Infrared Imaging Rad...
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doaj-f18efee3435f4c288728948edf57a1d82020-11-25T02:01:35ZengMDPI AGRemote Sensing2072-42922020-05-01121524152410.3390/rs12091524Impact of Aerosol Vertical Distribution on Aerosol Optical Depth Retrieval from Passive Satellite SensorsChong Li0Jing Li1Oleg Dubovik2Zhao-Cheng Zeng3Yuk L. Yung4Department of Atmospheric and Oceanic Science, School of Physics, Peking University, Beijing 100871, ChinaDepartment of Atmospheric and Oceanic Science, School of Physics, Peking University, Beijing 100871, ChinaLaboratoire d’Optique Atmosphérique, CNRS/Université Lille-1, 59655 Villeneuve d’Ascq, FranceDivision of Planetary and Geological Sciences, California Institute of Technology, Pasadena, CA 91125, USADivision of Planetary and Geological Sciences, California Institute of Technology, Pasadena, CA 91125, USAWhen retrieving Aerosol Optical Depth (AOD) from passive satellite sensors, the vertical distribution of aerosols usually needs to be assumed, potentially causing uncertainties in the retrievals. In this study, we use the Moderate Resolution Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) sensors as examples to investigate the impact of aerosol vertical distribution on AOD retrievals. A series of sensitivity experiments was conducted using radiative transfer models with different aerosol profiles and surface conditions. Assuming a 0.2 AOD, we found that the AOD retrieval error is the most sensitive to the vertical distribution of absorbing aerosols; a −1 km error in aerosol scale height can lead to a ~30% AOD retrieval error. Moreover, for this aerosol type, ignoring the existence of the boundary layer can further result in a ~10% AOD retrieval error. The differences in the vertical distribution of scattering and absorbing aerosols within the same column may also cause −15% (scattering aerosols above absorbing aerosols) to 15% (scattering aerosols below absorbing aerosols) errors. Surface reflectance also plays an important role in affecting the AOD retrieval error, with higher errors over brighter surfaces in general. The physical mechanism associated with the AOD retrieval errors is also discussed. Finally, by replacing the default exponential profile with the observed aerosol vertical profile by a micro-pulse lidar at the Beijing-PKU site in the VIIRS retrieval algorithm, the retrieved AOD shows a much better agreement with surface observations, with the correlation coefficient increased from 0.63 to 0.83 and bias decreased from 0.15 to 0.03. Our study highlights the importance of aerosol vertical profile assumption in satellite AOD retrievals, and indicates that considering more realistic profiles can help reduce the uncertainties.https://www.mdpi.com/2072-4292/12/9/1524aerosol vertical distributionaerosol optical depthsatellite AOD retrieval |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Chong Li Jing Li Oleg Dubovik Zhao-Cheng Zeng Yuk L. Yung |
spellingShingle |
Chong Li Jing Li Oleg Dubovik Zhao-Cheng Zeng Yuk L. Yung Impact of Aerosol Vertical Distribution on Aerosol Optical Depth Retrieval from Passive Satellite Sensors Remote Sensing aerosol vertical distribution aerosol optical depth satellite AOD retrieval |
author_facet |
Chong Li Jing Li Oleg Dubovik Zhao-Cheng Zeng Yuk L. Yung |
author_sort |
Chong Li |
title |
Impact of Aerosol Vertical Distribution on Aerosol Optical Depth Retrieval from Passive Satellite Sensors |
title_short |
Impact of Aerosol Vertical Distribution on Aerosol Optical Depth Retrieval from Passive Satellite Sensors |
title_full |
Impact of Aerosol Vertical Distribution on Aerosol Optical Depth Retrieval from Passive Satellite Sensors |
title_fullStr |
Impact of Aerosol Vertical Distribution on Aerosol Optical Depth Retrieval from Passive Satellite Sensors |
title_full_unstemmed |
Impact of Aerosol Vertical Distribution on Aerosol Optical Depth Retrieval from Passive Satellite Sensors |
title_sort |
impact of aerosol vertical distribution on aerosol optical depth retrieval from passive satellite sensors |
publisher |
MDPI AG |
series |
Remote Sensing |
issn |
2072-4292 |
publishDate |
2020-05-01 |
description |
When retrieving Aerosol Optical Depth (AOD) from passive satellite sensors, the vertical distribution of aerosols usually needs to be assumed, potentially causing uncertainties in the retrievals. In this study, we use the Moderate Resolution Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) sensors as examples to investigate the impact of aerosol vertical distribution on AOD retrievals. A series of sensitivity experiments was conducted using radiative transfer models with different aerosol profiles and surface conditions. Assuming a 0.2 AOD, we found that the AOD retrieval error is the most sensitive to the vertical distribution of absorbing aerosols; a −1 km error in aerosol scale height can lead to a ~30% AOD retrieval error. Moreover, for this aerosol type, ignoring the existence of the boundary layer can further result in a ~10% AOD retrieval error. The differences in the vertical distribution of scattering and absorbing aerosols within the same column may also cause −15% (scattering aerosols above absorbing aerosols) to 15% (scattering aerosols below absorbing aerosols) errors. Surface reflectance also plays an important role in affecting the AOD retrieval error, with higher errors over brighter surfaces in general. The physical mechanism associated with the AOD retrieval errors is also discussed. Finally, by replacing the default exponential profile with the observed aerosol vertical profile by a micro-pulse lidar at the Beijing-PKU site in the VIIRS retrieval algorithm, the retrieved AOD shows a much better agreement with surface observations, with the correlation coefficient increased from 0.63 to 0.83 and bias decreased from 0.15 to 0.03. Our study highlights the importance of aerosol vertical profile assumption in satellite AOD retrievals, and indicates that considering more realistic profiles can help reduce the uncertainties. |
topic |
aerosol vertical distribution aerosol optical depth satellite AOD retrieval |
url |
https://www.mdpi.com/2072-4292/12/9/1524 |
work_keys_str_mv |
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