Numerical simulation of influence of Tibetan Plateau uplift on winter dust cycle in Asian arid regions

Abstract

While it is now generally believed that the source of Chinese Loess Plateau deposit is the deserts in northern China and Mongolia (CM), the source for the dust deposit in eastern China and neighboring seas are still under debate. Using the dust-coupled CAM5 this study simulates responses of Asian dust cycle under varying Tibetan Plateau (TP) heights. Dust activities originated from central Asia (CA: 50–70°E, 35–50°N) and northern China-southern Mongolia (CM: 85–110°E, 35–45°N) under full TP (TP), medium TP (mTP) and no TP (nTP) are analyzed. Results show that as TP uplifts stepwise, the dust mass concentration in CA weakens slightly from 78 (nTP) to 74 (mTP) to 69 μg/kg (TP), whereas that in CM strengthens noticeably from 10 to 22 to 37 μg/kg correspondingly, more than tripled. These opposite and disparate responses between CA and CM dust concentration are likely because TP uplifting blocks mid-latitude winter westerly, reducing the emission in CA region, whereas the TP uplift enhances Siberia High Pressure thereby drying the soil and promoting dust emission. Further experiments with and without CA and CM sources under contemporary TP terrain indicate that CA source mainly affects local dust concentration and East Asia mid-high latitudes, but CM source contributes to dust in mid-low latitudes extending to as far as northwestern Pacific. Turning off the CM source reduces mid-low latitude concentration by up to 70 %, implying the key role that Cenozoic TP uplifting in the CM source formation and dust load in Asia.