INVITED ABSTRACT
Climate Response to a Geo-Engineered Brightening of Subtropical Boundary Clouds

SPENCER HILL (1), Yi Ming (2)

(1) University of California, Los Angeles, (2) Geophysical Fluid Dynamics Laboratory/NOAA, Princeton, NJ

     Abstract Number: 118
     Last modified: April 18, 2010

Abstract
We use a coupled atmosphere - slab ocean general circulation model to simulate how the climate system would react to an increase in reflected sunlight by artificially seeding subtropical boundary layer clouds with more sea salt particles. It is found that a five-fold increase in sea salt over the subtropical subsidence regions in North Pacific, South Pacific and South Atlantic gives rise to regional radiative forcing of ~ -10 W m$^(-2), mostly in short-wave, with a global-mean of -0.7 W m$^(-2). In spite of the highly concentrated forcing, the resulting cooling is spread not only to other parts of the Tropics, but also to the mid- and high latitudes, indicating that significant changes in large-scale circulation take place. The decrease in surface air temperature is averaged at 0.8 K. A detailed analysis of the simulated variations in Tropical circulation and rainfall patterns, in conjunction with theories, yields fundamental insights into some of the unintended consequences of geo-engineering.