SEARCHING FOR A REGIONAL FINGERPRINT OF AEROSOL RADIATIVE FORCING IN THE SOUTHEASTERN US

Although aerosols have long been considered to exert a cooling influen ce on the regional climate due to direct and indirect radiative forcin g, persuasive evidence of the response to this forcing has been lackin g. Here, we analyze the regional patterns of climate change in the Sou theast US during the period 1949-94 to search for a fingerprint of aer osol radiative forcing. The results show that direct and indirect radi ative forcing of both natural (such as Pinatubo volcanic aerosols) and anthropogenic aerosols (such as those transported from the polluted r egions of US) may be responsible for the regional cooling trend in the Southeast during the past 46 years. Lack of availability of long term measurements precludes a rigorous cause-and-effect analysis. Circumst antial evidence presented here amply justifies immediate establishment of a network of measurements of aerosol optical depth and cloud refle ctivity in the southeastern US.