Different Sources of 10-to 30-day Intraseasonal Variations of Autumn Snow over Western and Eastern Tibetan Plateau

Using the latest daily Moderate Resolution Imaging Spectroradiometer satellite snow cover data, the present study reveals distinctly different sources of 10- to 30-day intraseasonal snow cover variations over the western and eastern Tibetan Plateau (TP) during September-December. The intraseasonal snow variation over the western TP is related to a midlatitude wave train associated with the Arctic Oscillation and that over the eastern TP is related to a subtropical wave train triggered by the North Atlantic Oscillation. The Rossby wave train in both cases leads to anomalous water vapor convergence and ascending motion, which contributes to snow accumulation and positive snow cover anomalies. For the western TP snow events, the moisture comes from the Caspian Sea. During the eastern TP snow events, the moisture originates from the Bay of Bengal. Plain Language Summary Studies have identified the influence of snow cover over the Tibetan Plateau (TP) on climate in the surrounding regions. However, only a few studies have addressed intraseasonal snow cover variations over the plateau and their sources. In this study, we employ the latest snow cover data to investigate the cause of the 10- to 30-day intraseasonal snow cover variations over the TP in autumn and early winter. We found that the intraseasonal snow cover variations over the western and eastern TP have different moisture sources and atmospheric circulation patterns. For western TP snow, the moisture comes from the Caspian Sea. For eastern TP snow, the moisture originates from the Bay of Bengal. The intraseasonal snow cover changes in western and eastern TP are associated with the midlatitude and subtropical wave-type atmospheric circulation patterns, respectively.