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DOI	10.1175/JCLI-D-19-0833.1
	The recent decline and recovery of Indian summer monsoon rainfall: Relative roles of external forcing and internal variability
	Huang X.; Zhou T.; Turner A.; Dai A.; Chen X.; Clark R.; Jiang J.; Man W.; Murphy J.; Rostron J.; Wu B.; Zhang L.; Zhang W.; Zou L.
发表日期	2020
ISSN	0894-8755
起始页码	5035
结束页码	5060
卷号	33 期号:12
英文摘要	The Indian summer monsoon (ISM) rainfall affects a large population in South Asia. Observations show a decline in ISM rainfall from 1950 to 1999 and a recovery from 1999 to 2013. While the decline has been attributed to global warming, aerosol effects, deforestation, and a negative-to-positive phase transition of the interdecadal Pacific oscillation (IPO), the cause for the recovery remains largely unclear. Through analyses of a 57-member perturbed-parameter ensemble of model simulations, this study shows that the externally forced rainfall trend is relatively weak and is overwhelmed by large internal variability during both 1950-99 and 1999-2013. The IPO is identified as the internal mode that helps modulate the recent decline and recovery of the ISM rainfall. The IPO induces ISM rainfall changes through moisture convergence anomalies associated with an anomalous Walker circulation and meridional tropospheric temperature gradients and the resultant anomalous convection and zonal moisture advection. The negative-to-positive IPO phase transition from 1950 to 1999 reduces what would have been an externally forced weak upward rainfall trend of 0.01 to -0.15 mm day-1 decade-1 during that period, while the rainfall trend from 1999 to 2013 increases from the forced value of 0.42 to 0.68 mm day-1 decade-1 associated with a positive-to-negative IPO phase transition. Such a significant modulation of the historical ISM rainfall trends by the IPO is confirmed by another 100- member ensemble of simulations using perturbed initial conditions. Our findings highlight that the interplay between the effects of external forcing and the IPO needs be considered for climate adaptation and mitigation strategies in South Asia. © 2020 American Meteorological Society.
英文关键词	Atmospheric thermodynamics; Deforestation; Global warming; Moisture; Recovery; Indian summer monsoon; Indian summer monsoon rainfall; Inter-decadal pacific oscillations; Internal variability; Mitigation strategy; Moisture advection; Moisture convergence; Tropospheric temperature; Rain; atmospheric moisture; climate forcing; climate modeling; decadal variation; monsoon; rainfall; Walker circulation; South Asia
语种	英语
来源期刊	Journal of Climate
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/171545
作者单位	LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing, China; National Centre for Atmospheric Science, Department of Meteorology, University of Reading, Reading, United Kingdom; Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, Albany, NY, United States; Met Office Hadley Centre, Exeter, United Kingdom
推荐引用方式 GB/T 7714	Huang X.,Zhou T.,Turner A.,et al. The recent decline and recovery of Indian summer monsoon rainfall: Relative roles of external forcing and internal variability[J],2020,33(12).
APA	Huang X..,Zhou T..,Turner A..,Dai A..,Chen X..,...&Zou L..(2020).The recent decline and recovery of Indian summer monsoon rainfall: Relative roles of external forcing and internal variability.Journal of Climate,33(12).
MLA	Huang X.,et al."The recent decline and recovery of Indian summer monsoon rainfall: Relative roles of external forcing and internal variability".Journal of Climate 33.12(2020).