GEOGRAPHY

Sulphate aerosol contamination may lead to increased summer precipitation in arid regions of Central Asia


Schematic diagram of the mechanism by which anthropogenic sulfate aerosol pollution leads to increased summer precipitation in the arid zone of Central Asia. Photo courtesy of the author of the paper

The arid zone of central Asia, known as the “Central Asian arid zone”, which includes the five Central Asian countries and Xinjiang, is one of the largest non-zonal arid areas on the earth and the most vulnerable areas for water resources and ecosystems. According to research literature reports and a variety of observations, the arid region of Central Asia, especially Xinjiang region of China, has shown a significant trend of wetting in the past few decades. However, the influencing factors and driving mechanisms of this wetting trend are not fully understood so far.

Recently, Professor Xie Xiaoning of the Climate Simulation Team of the Institute of Earth Environment, Chinese Academy of Sciences, and other scientists from the United States, Europe and Japan conducted multi-model simulation research based on the Precipitation Drive and Response Model Comparison Program (PDRMIP).

Their findings suggest that anthropogenic sulfate aerosol pollution in South and East Asia leads to a significant increase in summer precipitation, especially convective precipitation and extreme precipitation, in arid regions of Central Asia.

“This explains the significant wetting trend in the arid regions of Central Asia.” Xie Xiaoning recounted, “The increase in sulfate aerosol concentration in polluted areas in South and East Asia reduces the atmospheric temperature in the mid-latitudes of Asia through a fast reaction process, thereby triggering the Asian westerly jet stream in the upper troposphere to move in the direction of the equator. ”

“Through the analysis of the water vapor budget, we also found that the southward movement of the westerly jet stream is conducive to the increase in water vapor supply from low latitudes and the accumulation of water vapor in the arid areas of Central Asia.” Xie further explained, “In contrast, absorbent black carbon aerosols will cause the westward jet stream in Asia to move northward, resulting in a decrease in summer precipitation in the arid region of Central Asia, which may partially offset the climatic effects of sulfate aerosols.” ”

The findings were published in Communications Earth & Environment.

Experts in this field believe that the results of this study also show that there is a remote correlation between precipitation anomalies in the arid region of Central Asia and anthropogenic aerosol emissions in South and East Asia, highlighting the long-range effects of anthropogenic aerosols on atmospheric circulation and water cycle, and pointing out that climate change in northwest China is not only affected by global greenhouse gas emissions, but also relies on aerosol emissions from polluted areas in South and East Asia, and also provides new clues for accurately predicting future climate change in northwest China.

It is reported that the research was jointly funded by the National Natural Science Foundation of China (41991254) and the Strategic Leading Science and Technology Project of the Chinese Academy of Sciences (XDB40030100). (Source: China Science News, Zhang Xingyong, Yan Tao)

Information about the paper:https://doi.org/10.1038/s43247-022-00660-x



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