The source contributions to the dust over the Tibetan Plateau: A modelling analysis

Atmospheric dust is the main aerosol component over the Tibetan Plateau (TP). The atmospheric dust over the TP influences climate at local and regional scales through its direct effects on solar and longwave radiation. There are various sources of atmospheric dust over the TP, including the semiarid and arid areas in East Asia as a near source and those in the Middle East and Central Asia and North Africa as remote sources. This study estimates the contributions of these sources to the atmospheric dust over the TP based on a five-year simulation (2010-2014) of the Weather Research and Forecasting Model Coupled with Chemistry (WRF-Chem). The contributions of all sources were higher in spring than in the other seasons, with the highest dust loading and concentrations in spring over the TP. The dust in the middle to high troposphere over the TP had diameters varying from 0.04 to 2.5 mu m, showing higher dust number concentrations in spring (at 500 hPa) than in other seasons (at 300 hPa). TP was mainly influenced by East Asian source, which dominated the dust loading over the TP with a contribution of 59-78% in all four seasons. As a result, the East Asian source affected the dust concentration at 500 hPa over the TP by contributing 55% in summer, 44% in autumn, and 27-36% in spring and winter with respect to those of the North African and the Middle East and Central Asian sources. The North African and the Middle East and Central Asian sources influenced the TP through a mainly northern route in the middle to upper troposphere from Central Asia to the TP. The dust concentration at 300 hPa over the TP was dominated by dust from the North African and the Middle East and Central Asian sources by a contribution of 31%-58% for North Africa and 36% for the Middle East and Central Asia in the four seasons.