| Summary: | The Tibetan Plateau (TP) has recently been polluted by strong anthropogenic emissions from South Asia. However, the mechanisms controlling the atmospheric circulations conducive to the aerosol transport to the TP are poorly understood. Here we show that winter loss of Arctic sea-ice over the sub-polar North Atlantic boosts the aerosol delivery toward the TP in April, when the aerosol loading is at its climatological maximum, preceding the Indian summer monsoon onset. Low sea-ice in February weakens the polar jet, which leads to the decreased Ural snowpack through a lessened transport of oceanic air. The decreased snowpack persisting to April reinforces the Ural pressure ridge and the East Asian trough, parts of a quasi-stationary Rossby wavetrain extending across Eurasia. These conditions facilitate the enhanced subtropical westerly jet at the southern edge of the TP, invigorating upslope wind combined with mesoscale updrafts wafting upstream emissions over the Himalayas onto the TP.
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