Influence of the land surface in the Asian summer monsoon: external conditions versus internal feedbacks

There is a surprising consistency among the various models such that stronger summer monsoons (defined as high area-average precipitation over South Asia) are associated with greater land-sea temperature contrast (i.e. higher land temperatures), lower sea level pressure over land, less snow cover, and greater soil moisture. In a sensitivity study with land albedos uniformly raised from 0.13 to 0.20 in one of the models, the winter-spring-summer sequence over southern Asia shows that there is a high sensitivity to the specified land albedos. Lower land albedos are associated with warmer land temperatures, greater land-sea temperature contrast, and a stronger Asian summer monsoon. There is also a positive feedback between soil moisture and precipitation (increased soil moisture provides a surface moisture source for further precipitation). -Author