Washington, July 16 : Researchers from the National Center for Atmospheric Research have analyzed that black carbon aerosols cause reduced monsoon rainfall over India.
They analyzed a six-member ensemble of twentieth-century simulations with changes to only time-evolving global distributions of black carbon aerosols in a global coupled climate model to study the effects of black carbon (BC) aerosols on the Indian monsoon.
According to their findings, the BC aerosols act to increase lower-tropospheric heating over South Asia and reduce the amount of solar radiation reaching the surface during the dry season.
With the onset of the monsoon, the reduced surface temperatures in the Bay of Bengal, Arabian Sea, and over India that extend to the Himalayas act to reduce monsoon rainfall over India itself, with some small increases over the Tibetan Plateau.
Precipitation over China generally decreases due to the BC aerosol effects.
During the summer monsoon season, the model experiments show that BC aerosols have likely contributed to observed decreasing precipitation trends over parts of India, Bangladesh, Burma, and Thailand.
These experiments point to the regional importance of BC aerosols for rainfall patterns over much of Asia, and in the Indian monsoon region in particular, and rely in part on changes to sea surface temperatures in the Arabian Sea and Bay of Bengal during March-April-May period that extend to the summer monsoon season to contribute to the decreases of rainfall over parts of India due to BC aerosols.