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Role of Maritime Continent Land Convection on the Mean State and MJO Propagation

Cited 30 time in Web of Science Cited 29 time in Scopus
Authors

Ahn, Min-Seop; Kim, Daehyun; Ham, Yoo-Geun; Park, Sungsu

Issue Date
2020-03
Publisher
American Meteorological Society
Citation
Journal of Climate, Vol.33 No.5, pp.1659-1675
Abstract
The Maritime Continent (MC) region is known as a "barrier" in the life cycle of the Madden-Julian oscillation (MJO). During boreal winter, the MJO detours the equatorial MC land region southward and propagates through the oceanic region. Also, about half of the MJO events that initiate over the Indian Ocean cease around the MC. The mechanism through which the MC affects MJO propagation, however, has remained unanswered. The current study investigates the MJO-MC interaction with a particular focus on the role of MC land convection. Using a global climate model that simulates both mean climate and MJO realistically, we performed two sensitivity experiments in which updraft plume radius is set to its maximum and minimum value only in the MC land grid points, making convective top deeper and shallower, respectively. Our results show that MC land convection plays a key role in shaping the 3D climatological moisture distribution around the MC through its local and nonlocal effects. Shallower and weaker MC land convection results in a steepening of the vertical and meridional mean moisture gradient over the MC region. The opposite is the case when MC land convection becomes deeper and stronger. The MJO's eastward propagation is enhanced (suppressed) with the steeper (lower) mean moisture gradient. The moist static energy (MSE) budget of the MJO reveals the vertical and meridional advection of the mean MSE by MJO wind anomalies as the key processes that are responsible for the changes in MJO propagation characteristics. Our results pinpoint the critical role of the background moisture gradient on MJO propagation.
ISSN
0894-8755
URI
https://hdl.handle.net/10371/200963
DOI
https://doi.org/10.1175/JCLI-D-19-0342.1
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  • College of Natural Sciences
  • Department of Earth and Environmental Sciences
Research Area Climate Change, Earth & Environmental Data, Severe Weather, 기후과학, 위험기상, 지구환경 데이터과학

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