Simultaneous retrieval of aerosol and thin cirrus optical depths using MODIS airborne simulator data during CRYSTAL-FACE and CLAMS

Abstract

We have developed a new methodology to simultaneously retrieve the optical depths of aerosols and thin cirrus clouds over the oceans by using the Moderate Resolution Imaging Spectroradiometer (MODIS) Airborne Simulator (MAS) data. This methodology takes advantage of the fact that the visible (or a near-infrared window) reflectance from cirrus can be characterized by its correlation to the reflectance from a near-infrared band located in a strong water vapor absorption region. Once the reflectance due to cirrus has been removed, the residual reflectance in these bands is used to retrieve aerosol optical depth. Cirrus cloud properties are subsequently obtained by minimizing the difference between observed and calculated reflectance values stored in look-up tables that are constructed a priori and correlated to the retrieved aerosol optical depth. Examination of the data gathered from the recent Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) and Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) field campaigns demonstrates that our retrievals are consistent with both in-situ and ground based measurements. Copyright 2004 by the American Geophysical Union.