부산대학교 도서관

The role of aerosol on the snow darkening effect is considered one of the main factors contributing to snow melting and glacier retreat over the Himalayas and Tibetan Plateau (HTP). Using the International Centre for Theoretical Physics (ICTP)'s regional climate model, RegCM4, we examine the changes induced by aerosol deposition over the HTP snow and its dynamical impacts over northern India during the pre-monsoon season (March to June), which is critical for the inception and development of the monsoon. Sensitivity experiments with and without aerosol-induced snow darkening effects for the period 2006–2010 reveal that this effect causes a significant reduction of snow cover fraction by 10 to 15% and an increase in surface temperatures (> 4 °C), which improves the model performance when comparing against observations over the HTP. This response is dominated by dust deposition, which covers a larger area of the HTP compared to the black carbon. While incorporating aerosol-induced snow darkening effect, the precipitation decreases (~ 0.4–2 mm/day) over northern India due to intrusion of dry winds, which also enhance dust emissions over the Thar Desert. As a result of the decrease in precipitation, surface temperature increases and generates a low-pressure system over northern India, which further strengthens the dust transport and its burden. We also find decreases in precipitation extremes and increases in the number of consecutive dry days and extreme temperature conditions over northern India, implying strong links with changes in pre-monsoon dynamics. The aerosol-induced snow darkening effect thus facilitates an earlier monsoon onset over southern India, but the northward propagation of the precipitation band is limited by the enhanced northwesterly winds over the Indo-Gangetic Plain. [ABSTRACT FROM AUTHOR]