Aerosol optical depth retrieval over the NASA Stennis Space Center: MTI, MODIS, and AERONET

The Multispectral Thermal Imager (MTI) and the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-based aerosol optical depth (AOD) retrievals are compared to each other and to the sun photometer AOD measurements at the National Aeronautics and Space Administration's Stennis Aerosol Robotic Network (AERONET) site. The overall accuracy of the MODIS AOD retrieval is approximately the same as the accuracy of the MTI with close-to-nadir view (at large scattering angles) when compared with AERONET measurements. The accuracy of the MODIS AOD retrieval is found to be a function of the scattering angle (the angle between the direction of the incoming and the scattered photons). The root mean square error of the MODIS AOD retrieval at the Stennis site is found to increase from 0.04 at scattering angles between 90 degrees and 105 degrees to over 0.12 at scattering angles from 140 degrees to 165 degrees. Using only moderate scattering angles (< 105 degrees) can significantly increase the accuracy of the MODIS AOD retrievals.