An enhanced moisture convergence - Evaporation feedback mechanism for MJO air-sea interaction
Marshall, AG; Alves, O; Hendon, HH; andrew.marshall@metoffice.gov.uk
2008
发表期刊JOURNAL OF THE ATMOSPHERIC SCIENCES
ISSN0022-4928
卷号65期号:3页码:970-986
摘要Simulations using an atmospheric model forced with observed SST climatology and the same atmospheric model coupled to a slab-ocean model are used to investigate the role of air-sea interaction on the dynamics of the MJO. Slab-ocean coupling improved the MJO in Australia's Bureau of Meteorology atmospheric model over the Indo-Pacific warm pool by reducing its period from 70-100 to 45-70 days, thereby showing better agreement with the 30-80-day observed oscillation. Air-sea coupling improves the MJO by increasing the moisture flux in the lower troposphere prior to the passage of active convection, which acts to promote convection and precipitation on the eastern flank of the main convective center. This process is triggered by an increase in surface evaporation over positive SST anomalies ahead of the MJO convection, which are driven by the enhanced shortwave radiation in the region of suppressed convection. This in turn generates enhanced convergence into the region, which supports evaporation-wind feedback in the presence of weak background westerly winds. A subsequent increase in low-level moisture convergence acts to further moisten the lower troposphere in advance of large-scale convection in a region of reduced atmospheric pressure. This destabilizing mechanism is referred to as enhanced moisture convergaence-evaporation feedback (EMCEF) and is utilized to understand the role of air-sea coupling on the observed MJO. The EMCEF mechanism also reconciles traditionally opposing ideas on the roles of frictional wave-conditional instability of the second kind (CISK) and wind-evaporation feedback. These results support the idea that the MJO is primarily an atmospheric phenomenon, with air-sea interaction improving upon, but not critical for, its existence in the model.
部门归属[Marshall, Andrew G.; Alves, Oscar; Hendon, Harry H.] Bur Meteorol Res Ctr, Melbourne, Vic, Australia
学科领域Meteorology & Atmospheric Sciences
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收录类别sci
文献类型期刊论文
条目标识符http://ir.scsio.ac.cn/handle/344004/8435
专题海洋科技动态信息-印太暖池系统研究
通讯作者andrew.marshall@metoffice.gov.uk
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Marshall, AG,Alves, O,Hendon, HH,et al. An enhanced moisture convergence - Evaporation feedback mechanism for MJO air-sea interaction[J]. JOURNAL OF THE ATMOSPHERIC SCIENCES,2008,65(3):970-986.
APA Marshall, AG,Alves, O,Hendon, HH,&andrew.marshall@metoffice.gov.uk.(2008).An enhanced moisture convergence - Evaporation feedback mechanism for MJO air-sea interaction.JOURNAL OF THE ATMOSPHERIC SCIENCES,65(3),970-986.
MLA Marshall, AG,et al."An enhanced moisture convergence - Evaporation feedback mechanism for MJO air-sea interaction".JOURNAL OF THE ATMOSPHERIC SCIENCES 65.3(2008):970-986.
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