Mid-Holocene Ocean Feedback on Global Monsoon Area and Precipitation

Mid-Holocene ocean feedback on global monsoon area, global monsoon precipitation (GMP), and GMP intensity (GMPI) was investigated by a set of numerical experiments performed with the Community Climate System Model version 4. Results showed that ocean feedback induced an increase in land monsoon area for northern Africa but a decrease for Asia and North and South America, and led to an increase in ocean monsoon area for the western Indian Ocean and southeastern Pacific but a decrease for the eastern Indian Ocean, tropical western Pacific, and tropical West Atlantic between the mid-Holocene and pre-industrial period. Dynamic oceaninduced changes in GMP and GMPI were 10.9 x 10(9) m(3) d(-1) and -0.11 mm d(-1) between the two periods, respectively. Ocean feedback induced consistent change between the Northern and Southern Hemisphere land or ocean but opposite change between land and ocean in the Northern or Southern Hemisphere monsoon areas for monsoon precipitation. The mid-Holocene summer changes in meridional temperature gradient and land-sea thermal contrast were the underlying mechanisms.