A review of recent progress on Tibet’s role in the South Asian monsoon


The Tibetan Plateau exerts a profound influence on winds in boreal winter primarily through mechanical means, blocking flow to create waves in the jet stream that extend around Earth’s full circumference (e.g. Held et al., 2002). In contrast, this plateau was thought to influence boreal summer winds primarily through its thermal effects, providing a heat source over 4 km high and 2,000 km wide that generates the interhemispheric flow of the South Asian monsoon. But recent work has shown that although orography greatly strengthens the South Asian summer monsoon, it operates via a different mechanism that requires only a relatively narrow but continuous chain of mountains around the northern edge of the monsoon, rather than a broad plateau. This review presents a brief history of research on the role of orography in the South Asian summer monsoon, with a focus on recent work that frames monsoon dynamics in terms of modern theories for precipitating large-scale circulations. This review does not address the mechanical forcing by orography that seems important for East Asian climate (e.g. Wu et al., 2007; Wang et al., 2008; Molnar et al., 2010; Park et al., 2012).

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