Abstract. Mineral dust plays an important role in the climate of the Tibetan Plateau
(TP) by modifying the radiation budget, cloud macro- and microphysics,
precipitation, and snow albedo. Meanwhile, the TP, with the highest
topography in the world, can affect intercontinental transport of dust plumes
and induce typical distribution characteristics of dust at different
altitudes. In this study, we conduct a quasi-global simulation to
investigate the characteristics of dust source contribution and transport
over the TP at different altitudes by using a fully coupled
meteorology–chemistry model, the Weather Research and Forecasting model with chemistry (WRF-Chem), with a tracer-tagging technique.
Generally, the simulation reasonably captures the spatial distribution of
satellite-retrieved dust aerosol optical depth (AOD) at different altitudes.
Model results show that dust particles are emitted into atmosphere through
updrafts over major desert regions and then transported to the TP. The East
Asian dust (mainly from the Gobi and Taklamakan deserts) is transported southward
and is lifted up to the TP, contributing a mass loading of 50 mg m−2 at a height of
3 km and 5 mg m−2 at a height of 12 km over the northern slope of the
TP. Dust from North Africa and the Middle East are concentrated over both of the
northern and southern slopes below 6 km, where mass loadings range from 10
to 100 and 1 to 10 mg m−2 below 3 km and above 9 km,
respectively. As the dust is transported to the north and over the TP, mass
loadings are 5–10 mg m−2 above a height of 6 km. The dust mass flux carried from East Asia to the TP is 7.9 Tg yr−1, mostly
occurring at heights of 3–6 km. The dust particles from North Africa and the Middle East are transported eastward following the westerly jet and then
are carried into the TP at the west side with dust mass fluxes of 7.8 and 26.6 Tg yr−1, respectively. The maximum mass flux of the North African dust
mainly occurs at 0–3 km (3.9 Tg yr−1), while the Middle Eastern dust occurs at 6–9 km
(12.3 Tg yr−1). The dust outflow occurs on the east side (−17.89 Tg yr−1) and
south side (−11.22 Tg yr−1) of the TP, with a peak value (8.7 Tg yr−1) at
6–9 km. Moreover, the dust (by mass) is concentrated within the size range of
1.25–5.0 µm and the dust (by particle number) is concentrated in the size
range of 0.156–1.25 µm. Compared with other aerosols, the dust contributes to more than 50 % of the total AOD over the TP. The direct
radiative forcing induced by the dust is −1.28 W m−2 at the top of the
atmosphere (cooling), 0.41 W m−2 in the atmosphere (warming), and −1.68 W m−2 at the surface (cooling). Our quantitative analyses of the dust
contributions from different source regions and the associated radiative
forcing can help us to better understand the role of dust on the climate over the
TP and surrounding regions.
Outgoing longwave radiation and cloud radiative forcing of the Tibetan Plateau
