气候变化领域集成服务门户(CCPortal): A double ITCZ phenomenology of wind errors in the equatorial Atlantic in seasonal forecasts with ECMWF models

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DOI	10.5194/acp-19-11383-2019
	A double ITCZ phenomenology of wind errors in the equatorial Atlantic in seasonal forecasts with ECMWF models
	Shonk J.K.P.; Demissie T.D.; Toniazzo T.
发表日期	2019
ISSN	16807316
起始页码	11383
结束页码	11399
卷号	19 期号:17
英文摘要	Modern coupled general circulation models produce systematic biases in the tropical Atlantic that hamper the reliability of long-range predictions. This study focuses on a common springtime westerly wind bias in the equatorial Atlantic in seasonal hindcasts from two coupled models - ECMWF System 4 and EC-Earth v2.3 - and in hindcasts also based on System 4, but with prescribed sea-surface temperatures. The development of the equatorial westerly bias in early April is marked by a rapid transition from a wintertime easterly, cold tongue bias to a springtime westerly bias regime that displays a marked double intertropical convergence zone (ITCZ). The transition is a seasonal feature of the model climatology (independent of initialisation date) and is associated with a seasonal increase in rainfall where a second branch of the ITCZ is produced south of the Equator. Excess off-equatorial convergence redirects the trade winds away from the Equator. Based on arguments of temporal coincidence, the results of our analysis contrast with those from previous work, and alleged causes hereto identified as the likely cause of the equatorial westerly bias in other models must be discarded. Quite in general, we find no evidence of remote influences on the development of the springtime equatorial bias in the Atlantic in the IFS-based models. Limited evidence however is presented that supports the hypothesis of an incorrect representation of the meridional equatorward flow in the marine boundary layer of the southern Atlantic as a contributing factor. Erroneous dynamical constraints on the flow upstream of the Equator may generate convergence and associated rainfall south of the Equator. This directs attention to the representation of the properties of the subtropical boundary layer as a potential source for the double ITCZ bias. © 2019 Author(s).
语种	英语
scopus关键词	general circulation model; hindcasting; intertropical convergence zone; sea surface temperature; seasonal variation; weather forecasting; westerly; wind measurement; Atlantic Ocean; Atlantic Ocean (Equatorial)
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/144161
作者单位	National Centre for Atmospheric Science, University of Reading, Reading, United Kingdom; NORCE Climate, NORCE Norwegian Research Centre AS, Bergen, Norway; CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS) East Africa, Addis Ababa, Ethiopia
推荐引用方式 GB/T 7714	Shonk J.K.P.,Demissie T.D.,Toniazzo T.. A double ITCZ phenomenology of wind errors in the equatorial Atlantic in seasonal forecasts with ECMWF models[J],2019,19(17).
APA	Shonk J.K.P.,Demissie T.D.,&Toniazzo T..(2019).A double ITCZ phenomenology of wind errors in the equatorial Atlantic in seasonal forecasts with ECMWF models.Atmospheric Chemistry and Physics,19(17).
MLA	Shonk J.K.P.,et al."A double ITCZ phenomenology of wind errors in the equatorial Atlantic in seasonal forecasts with ECMWF models".Atmospheric Chemistry and Physics 19.17(2019).