Shortwave Aerosol Radiative Forcing from MODIS and CERES observations over the oceans

Abstract

Using spatially and temporally collocated data sets from the Clouds and Earth's Radiant Energy System (CERES) and Moderate-Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra satellite, a new strategy is presented for studying the Shortwave Aerosol Radiative Forcing (SWARF) over the global oceans. Using collocated data, for September 2000, the global averaged optical thickness (τ0.55) for cloud-free CERES pixels is 0.07 with a SWARF of -6 Wm-2. The τ0.55 and SWARF values derived from two independent instruments are in excellent agreement with the following relationship: SWARF = 0.35 -105.34τ0.55 +61.47τ0.552 (0 ≤ τ0.55 ≤ 0.7) Wm-2. The synergistic use of the MODIS and CERES data sets can be used to provide independent estimates of SWARF, and can be used as a validation tool for studies that attempt to model the role of aerosols on climate.