Quantification of aerosol-cloud shortwave radiative effects in stratiform cloud cover

Warm stratiform clouds in the tropics are highly reflective and important in understanding Earth's radiation balance. Given the sign and magnitude of aerosols' radiative effects on clouds is still uncertain, changes aerosol have on tropical stratiform cloud could alter the radiation balance. To better understand aerosols effects on stratiform cloud brightness, four years of data from the NASA-A train satellite constellation from 30° S to 30° N is analyzed. The relationship between aerosol index and changes to cloud shortwave radiative forcing (CSWRF) is analyzed. Observations show albedo and cloud fraction are two important governing factors to CSWRF; changes in either one due to increased aerosol alters CSWRF. The relationship between aerosol index, albedo, and cloud fraction, however, relies strongly on the local conditions, accounted for through the estimated inversion strength and relative humidity. The dependence of CSWRF on albedo, cloud fraction, and local conditions will be demonstrated. A calculated ∂CSWRF/∂AI found using knowledge of the dependencies will be presented and compared to the retrieved value. Future work will include expanding the area of interest and investigating possible cloud regimes.