Exploring precipitation extremes and their connection to land surface coupling in the La Plata Basin.

ANNA A. SÖRENSSON; MENÉNDEZ C.G,; RUSCICA, R.C.; SAMUELSSON, PATRICK

Floreanapolis

Conferencia; CLARIS LPB M26 Meeting.; 2010

Precipitation extremes and impacts of land surface condition on the atmosphere are studied over La Plata Basin, with the Rossby Centre regional atmospheric climate model, RCA3. As a measure of extreme events, the 95th percentile of daily rainfall is calculated for the periods 1980-99 and 2080-99 (A1B scenario). The risk that the 1980-99 daily heavy rainfall is exceeded during 2080-99 is around 1.5-2.5 over large parts of the La Plata Basin, especially for summer and winter. The soil moisture ? atmosphere coupling is calculated for the South American Monsoon System (SAMS) of 1992-93. The coupling between soil moisture and evapotranspiration as well as precipitation is found to be large especially over La Plata Basin. An association between the soil moisture-atmosphere coupling and the occurrence of extremes is found over the basin, with coupling included in the simulations favouring extreme events over Uruguay, while coupling tends to suppress extremes over parts of northern Argentina and the Buenos Aires province.