Modulation of South Asian Jet Wave Train on the Extreme Winter Precipitation over Southeast China Comparison between 2015/16 and 2018/19

Two extremely wet winters in 2015/16 and 2018/19 over Southeast China are compared in this study. South-to-north discrepancies appear in the spatial distribution of precipitation, with anomalous precipitation centered over the southeast coast in 2015/16 and the lower reaches of Yangtze River valley...

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Bibliographic Details
Published inJournal of climate Vol. 33; no. 10; pp. 4065 - 4081
Main Authors Li, Xiuzhen, Wen, Zhiping, Huang, Wan-Ru
Format Journal Article
LanguageEnglish
Published Boston American Meteorological Society 15.05.2020
Subjects
Advection
Anticyclones
El Nino
Extreme weather
Planetary waves
Precipitation
River valleys
Rivers
Rossby waves
Spatial distribution
Storms
Studies
Transport
Wave packets
Wave propagation
Wave trains
Wavelength
Wind
Winter precipitation
China
Bay of Bengal
Japan
Yangtze River
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Summary:Two extremely wet winters in 2015/16 and 2018/19 over Southeast China are compared in this study. South-to-north discrepancies appear in the spatial distribution of precipitation, with anomalous precipitation centered over the southeast coast in 2015/16 and the lower reaches of Yangtze River valley in 2018/19, respectively. Both instances of enhanced precipitation are ascribed mainly to warm and moist advection from the south, with transport in 2015/16 partly by a deepened India–Burma trough to the west, whereas with transport in 2018/19 mainly by a subtropical western North Pacific anticyclone (WNPAC). Both the India–Burma trough and WNPAC are maintained by the wave trains propagating along the South Asian jet, which are zonally offset by a quarter-wavelength. Further study of the wave train sources in 2015/16 and 2018/19 shows that they both tend to originate from extremely strong storm-track activity over the North Atlantic but have different displacement. The former is located more northeastward than the mean storm track and is modulated by a strong positive NAO, whereas the latter lies over the midlatitude central North Atlantic along with a circumglobal teleconnection. These differences further result in a quarter-wavelength offset in the Rossby wave source near the entrance of the South Asian jet by the convergence of upper-level divergent wind.
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ISSN:0894-8755
1520-0442
DOI:10.1175/jcli-d-19-0678.1