Thursday, 18 January 2007: 2:15 PM
The impacts of aerosols on Asian summer monsoon rainfall and circulation
214D (Henry B. Gonzalez Convention Center)
In a recent paper, Lau et al (2006) proposed the “Elevated Heat Pump” hypothesis, suggesting that absorption of solar radiation by dust stacked up against the southern slope of Tibetan Plateau can heat up the elevated surface air, and trigger a positive feedback in deep convection over the foothills of the Himalayas, which draws in warm and moist air from the Indian Ocean, and brings rain to the northern India in May and June. In this work, we have provided preliminary observational evidence of the EHP. Results from the analysis of observation are consistent with the key features of the EHP effect in showing that absorbing aerosol is associated with a) anomalous warming of the upper troposphere over the Tibetan Plateau in May and June, b) an advance of the monsoon season, with increased rainfall coming to northern India during May, and c) subsequent enhancement of the monsoon rain over India in June-July. The downstream impacts of the EHP on the East Asian summer monsoon will also be discussed.