Dynamical Control of the Tibetan Plateau on the East Asian Summer Monsoon

• Published in: Geophysical research letters 2019-07, Vol.46 (13), p.7672-7679
• Main Authors: Son, Jun‐Hyeok, Seo, Kyong‐Hwan, Wang, Bin
• Format: Article
• Language: English
• Subjects: Computer simulation; Drag effects; dynamical response; East Asian monsoon; GCM; General circulation models; Heating; monsoon; Monsoons; Mountains; Northern Hemisphere; Physics; Planetary waves; Plateaus; Precipitation; Rossby waves; Summer; Summer monsoon; Summer precipitation; Wind
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2019GL083104

The origin of the East Asian summer monsoon (EASM)—the sole monsoon existing in the subtropics‐midlatitude in the northern hemisphere—has long been recognized as an elevated heating and mechanical forcing of the Tibetan Plateau, and the land‐sea zonal heat contrast. However, the relative contribution of individual processes to the generation of the East Asian summer monsoon and therefore the underlying basic physics are unexplored. Here we show that the EASM is mainly driven by the dynamical effect of the Tibetan Plateau, in which forced topographic Rossby waves induce downstream southerlies, a crucial factor in EASM precipitation. From idealized general circulation model simulations, the dynamical effect of mountains is revealed to account for ~65% of the total East Asian summer precipitation, whereas the elevated heating and land‐sea heat contrast are only responsible for ~15% each and the mountain‐drag effect accounts for less than 5%. Key Points The origin of the East Asian summer monsoon is the fluid dynamical effect due to the Tibetan Plateau This dynamical response to Tibetan Plateau forcing explains ~65% of total precipitation over East Asian summer monsoon region Mountain forced stationary Rossby waves induce zonal pressure gradient and southerly winds over East Asia