气候变化领域集成服务门户(CCPortal): Quasi-Biweekly Mode of the Asian Summer Monsoon Revealed in Bay of Bengal Surface Observations

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DOI	10.1029/2020JC016271
	Quasi-Biweekly Mode of the Asian Summer Monsoon Revealed in Bay of Bengal Surface Observations
	Sree Lekha J.; Lucas A.J.; Sukhatme J.; Joseph J.K.; Ravichandran M.; Suresh Kumar N.; Farrar J.T.; Sengupta D.
发表日期	2020
ISSN	21699275
卷号	125 期号:12
英文摘要	Asian summer monsoon has a planetary-scale, westward propagating “quasi-biweekly” mode of variability with a 10–25 day period. Six years of moored observations at 18°N, 89.5°E in the north Bay of Bengal (BoB) reveal distinct quasi-biweekly variability in sea surface salinity (SSS) during summer and autumn, with peak-to-peak amplitude of 3–8 psu. This large-amplitude SSS variability is not due to variations of surface freshwater flux or river runoff. We show from the moored data, satellite SSS, and reanalyses that surface winds associated with the quasi-biweekly monsoon mode and embedded weather-scale systems, drive SSS and coastal sea level variability in 2015 summer monsoon. When winds are calm, geostrophic currents associated with mesoscale ocean eddies transport Ganga-Brahmaputra-Meghna river water southward to the mooring, salinity falls, and the ocean mixed layer shallows to 1–10 m. During active (cloudy, windy) spells of quasi-biweekly monsoon mode, directly wind-forced surface currents carry river water away to the east and north, leading to increased salinity at the moorings, and rise of sea level by 0.1–0.5 m along the eastern and northern boundary of the bay. During July–August 2015, a shallow pool of low-salinity river water lies in the northeastern bay. The amplitude of a 20-day oscillation of sea surface temperature (SST) is two times larger within the fresh pool than in the saltier ocean to the west, although surface heat flux is nearly identical in the two regions. This is direct evidence that spatial-temporal variations of BoB salinity influences sub-seasonal SST variations, and possibly SST-mediated monsoon air-sea interaction. © 2020. American Geophysical Union. All Rights Reserved.
语种	英语
来源期刊	Journal of Geophysical Research: Oceans
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/186551
作者单位	Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore, India; Scripps Institution of Oceanography and Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, United States; National Institute for Ocean Technology, Ministry of Earth Sciences, Chennai, India; National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco da Gama, India; Indian National Centre for Ocean Information Services, Ministry of Earth Sciences, Hyderabad, India; Woods Hole Oceanographic Institution, Woods Hole, MA, United States; Centre for Atmospheric and Oceanic Sciences and Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India
推荐引用方式 GB/T 7714	Sree Lekha J.,Lucas A.J.,Sukhatme J.,et al. Quasi-Biweekly Mode of the Asian Summer Monsoon Revealed in Bay of Bengal Surface Observations[J],2020,125(12).
APA	Sree Lekha J..,Lucas A.J..,Sukhatme J..,Joseph J.K..,Ravichandran M..,...&Sengupta D..(2020).Quasi-Biweekly Mode of the Asian Summer Monsoon Revealed in Bay of Bengal Surface Observations.Journal of Geophysical Research: Oceans,125(12).
MLA	Sree Lekha J.,et al."Quasi-Biweekly Mode of the Asian Summer Monsoon Revealed in Bay of Bengal Surface Observations".Journal of Geophysical Research: Oceans 125.12(2020).