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Roles of Double Low‐Level Jets in the Generation of Coexisting Inland and Coastal Heavy Rainfall Over South China During the Presummer Rainy Season
Author(s) -
Liu Xi,
Luo Yali,
Huang Ling,
Zhang DaLin,
Guan Zhaoyong
Publication year - 2020
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2020jd032890
Subject(s) - geostrophic wind , climatology , front (military) , environmental science , zonal and meridional , monsoon , wind shear , china , atmospheric sciences , wind speed , geography , geology , meteorology , archaeology
In this study, the key dynamic factors influencing the formation of six heavy‐rainfall events with coexisting inland and coastal rainfall over south China during May–June 2011–2017 are investigated using global ensemble forecasts from the European Centre for Medium‐Range Weather Forecasts. An ensemble sensitivity analysis and comparisons between the identified good and bad members are conducted. Results confirm the importance of the synoptic low‐level jet (SLLJ) and boundary layer jet (BLJ), but with different contributions, in determining the generation of the inland and coastal rainbelts, respectively. The inland heavy rainfall is closely related to both the SLLJ and BLJ, especially their meridional wind components. The more intense cold or quasi‐stationary front, low‐level vortex, or shear line accompanied by the stronger geostrophic southerly winds within both jets over inland and coastal south China is, the more rainfall over the inland region is favored. The ageostrophic southerly winds of the BLJ make limited contributions to the inland rainfall production but exert greater impacts on the generation of extreme (yet localized) coastal rainfall. The geostrophic meridional winds and associated low‐level front/vortex also play a nonnegligible but indispensable role in producing the coastal rainfall. These findings add to our knowledge of heavy rainfall in the East Asian monsoon region.