A novel back-trajectory analysis of the origin of black carbon transported to the Himalayas and Tibetan Plateau during 1996-2010

Abstract

Black carbon (BC) deposited on snow and ice accelerates glacier melting and contributes to climate change of the Himalayas and Tibetan Plateau (HTP). Taking into account emissions, hydrophilic-to-hydrophobic conversion, and removal processes of BC, a novel back-trajectory approach is developed to study the origin of BC reaching the HTP. The results indicate that BC received by the HTP increased by 41% from 1996 to 2010, implying that the BC problem is accelerating in the HTP region. South Asia and East Asia are the main source regions, accounting for 67% and 17% of BC transported to the HTP on an annual basis, followed by Former USSR (∼8%), Middle East (∼4%), Europe (∼2%), and Northern Africa (∼1%). BC reaching the HTP is high in winter and low in summer, and the relative contributions of different source regions vary with seasons. We show the seasonal spatial distribution of BC sources directly on a 0.5° × 0.5° grid, which provides information to policymakers about the best target areas for mitigating the climate changes and other effects on the HTP. Copyright 2012 by the American Geophysical Union.