Abstract
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%.
| Original language | English |
|---|---|
| Pages (from-to) | 7672-7679 |
| Number of pages | 8 |
| Journal | Geophysical Research Letters |
| Volume | 46 |
| Issue number | 13 |
| DOIs | |
| State | Published - Jul 16 2019 |
Funding
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP; NRF‐ 2018R1A2A2A05018426) and the KMA Research and Development Program under grant KMI2018‐01012. We would like to thank Daehyun Kim for the discussion of Rossby wave dynamics, Stephen Garner and Jin‐Ho Yoon for their helpful comments, and the Editor Suzanna Camargo for the thoughtful comments and encouragement. We are grateful to the two reviewers for their valuable comments and suggestions, which improved the paper. The ERA‐ Interim reanalysis is available at http:// www.ecmwf.int, precipitation is at https://precip.gsfc.nasa.gov, SST is downloaded from https://www.esrl. noaa.gov/psd/data/gridded/data.noaa. oisst.v2.html, and the AM2.1 idealized model simulation products are stored at https://climate.pusan.ac.kr/climate1/ 48095/subview.do.
Keywords
- dynamical response
- GCM
- monsoon