A Critical Look at Deriving Monthly Aerosol Optical Depth From Satellite Data

Levy, R.C., G. Leptoukh, R.A. Kahn, V. Zubko, A. Gopalan, and L.A. Remer (2009), A Critical Look at Deriving Monthly Aerosol Optical Depth From Satellite Data, IEEE Trans. Geosci. Remote Sens., 47, 2942-2956, doi:10.1109/TGRS.2009.2013842.
Abstract

Satellite-derived aerosol data sets, such as those provided by NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instruments, are greatly improving our understanding of global aerosol optical depth (AOD). Yet, there are sampling issues. MODIS’ specific orbital geometry, convolved with the need to avoid bright surfaces (glint, desert, clouds, etc.), means that AOD can be under- or over-sampled in places. When deriving downstream products, such as daily or monthly gridded AOD, one must consider the spatial and temporal density of the measurements relative to the gradients of the true AOD. Additionally, retrieval confidence criteria should be considered. Averaged products are highly dependent on choices made for data aggregation and weighting, and sampling errors can be further propagated when deriving regional or global “mean” AOD. Different choices for aggregation and weighting result in estimates of regional and global means varying by 30% or more. The impacts of a particular averaging algorithm vary by region and surface type and can be shown to represent different tolerance for clouds and retrieval confidence.

PDF of Publication
Download from publisher's website
Research Program
Atmospheric Composition Modeling and Analysis Program (ACMAP)
Radiation Science Program (RSP)
Mission
Aqua-MODIS
Terra-MODIS

 

Disclaimer: This material is being kept online for historical purposes. Though accurate at the time of publication, it is no longer being updated. The page may contain broken links or outdated information, and parts may not function in current web browsers. Visit https://espo.nasa.gov for information about our current projects.