A critical examination of spatial biases between MODIS and MISR aerosol products ndash; application for potential AERONET deployment

摘要

AErosol RObotic NETwork (AERONET) data are the primary benchmark forevaluating satellite-retrieved aerosol properties. However, despite itsextensive coverage, the representativeness of the AERONET data is rarelydiscussed. Indeed, many studies have shown that satellite retrieval biaseshave a significant degree of spatial correlation that may be problematic forhigher-level processes or inverse-emissions-modeling studies. To considerthese issues and evaluate relative performance in regions of few surfaceobservations, cross-comparisons between the Aerosol Optical Depth (AOD)products of operational MODIS Collection 5.1 Dark Target (DT) andoperational MODIS Collection 5.1 Deep Blue (DB) with MISR version 22 wereconducted. Through such comparisons, we can observe coherent spatialfeatures of the AOD bias while sidestepping the full analysis required fordetermining when or where either retrieval is more correct. We identify regions where MODIS toMISR AOD ratios were found to be above 1.4 and below 0.7. Regions where lower boundary condition uncertainty is likely to be adominant factor include portions of Western North America, the Andesmountains, Saharan Africa, the Arabian Peninsula, and Central Asia.Similarly, microphysical biases may be an issue in South America, andspecific parts of Southern Africa, India Asia, East Asia, and Indonesia.These results help identify high-priority locations for possible futuredeployments of both in situ and ground based remote sensing measurements.The Supplement includes a kml file.