Improved MODIS Aerosol Retrieval Using Modified VIS/SWIR Surface Albedo Ratio Over Urban Scenes
Improved MODIS Aerosol Retrieval Using Modified VIS/SWIR Surface Albedo Ratio Over Urban Scenes
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DOI：
10.1117/12.800388
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发表时间：
2008-07
影响因子：
8.2
通讯作者：
M. Oo;M. Jerg;E. Hernández;Ana J. Picon;B. Gross;F. Moshary;Samir A. Ahmed
中科院分区：
文献类型：
--
作者：
M. Oo;M. Jerg;E. Hernández;Ana J. Picon;B. Gross;F. Moshary;Samir A. Ahmed
在本文中，我们展示了一个区域的方法，中分辨率成像光谱仪（MODIS）的气溶胶光学厚度（AOD）反演城市场景。通过同时使用MODIS和AERONET（AERONET）天空辐射计数据，我们表明，对于城市场景，可见光（维斯）（0.47-和0.66-<$m）和短波-红外（2.12-<$m）通道之间的表面反射比在MODIS收集5（C 005）检索显着低估。这导致低估维斯地面反射率，从而导致显著高估维斯通道中的AOD。由于散射几何形状的依赖是弱的，修订后的表面反射率比地图的空间分辨率下降到1.5公里，可以开发，允许气溶胶反演在这些决议。与AERONET相比，应用此程序可显著降低MODIS检索的AOD偏差。例如，对于纽约市，在10 km分辨率下，使用C 005的MODIS-AERONET回归为AERONET + 0.11，R 2 = 0.85，而对于区域方法，我们应用AERONET + 0.04，R 2 = 0.92的结果。这种改进的性能保持甚至高分辨率检索下降到1.5公里的回归<$MODIS = 0.96 <$AERONET + 0.02，R 2 = 0.88。此外，我们表明，这种方法可以扩展到其他城市的场景，如墨西哥城与类似的结果，并讨论了C 005气溶胶光学厚度高估对PM2.5监测的影响。此外，与该地区分布式PM2.5传感器的比较证实，C 005的AOD高估计值无法用城市排放过量来解释。
In this paper, we demonstrate a regional approach to Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) retrieval over urban scenes. By using simultaneous MODIS and AErosol RObotic NETwork (AERONET) sky radiometer data, we show that for urban scenes, the surface reflectance ratios between the visible (VIS) (0.47- and 0.66-¿m) and shortwave-infrared (2.12-¿m) channels used in the MODIS Collection 5 (C005) retrieval are significantly underestimated. This leads to an underestimate in the VIS ground albedos resulting in a significant overestimate of the AOD in the VIS channels. Since the dependence on scattering geometry is weak, revised surface reflectance ratio maps at spatial resolutions down to 1.5 km can be developed, permitting aerosol retrievals at these resolutions. Applying this procedure results in significant reductions in MODIS-retrieved AOD bias in comparison to AERONET. As an example, for New York City, at the operational 10-km resolution, the MODIS-AERONET regression using C005 is ¿MODIS = 1.24 ¿AERONET + 0.11, R 2 = 0.85 , while for the regional method, we apply results in ¿MODIS = 1.02 ¿AERONET + 0.04, R 2 = 0.92 . This improved performance is maintained even for high-resolution retrieval down to 1.5 km with a regression of ¿MODIS = 0.96 ¿AERONET + 0.02, R 2 = 0.88. In addition, we show that this method can be extended to other urban scenes such as Mexico City with similar results and discuss the implications of C005 AOD overestimates on PM2.5 monitoring. Furthermore, comparisons with distributed PM2.5 sensors in the region confirm that the high estimates of AOD from C005 cannot be explained by excess urban emissions.