CHARACTERISTICS AND CIRCULATION BACKGROUND OF SHANGHAI SUMMER SEA BREEZE FRONT AND ITS INDUCED CONVECTION
GU Wen
ZHANG Jin
TAN Jian-guo
DAI Jian-hua
YUE Cai-jun
Abstract：Based on the Doppler radar,encrypted automatic stations and NCEP/NCAR reanalysis data from June to September,2011-2014,the spatial and temporal distribution of a sea breeze front (SBF) and its induced convection were investigated.The results show that during the 4 years the summer SBF landed 65 times,while SBF-induced convection occurred 19 times.The SBF is prone to land at 0900 to 1200 (local time) withan average duration of 5.2 hours.SBF-induced convection tends to happen at 1300 to 1500 withan average duration of 2.5 hours.It has strong local characteristic,most likely to occur in the downtown areas,Pudong New District and Baoshan District.The SBF is divided into 3 categories according to its landing site:N-SBF landing from Yangtze River estuary,S-SBF landing from Hangzhou Bay and SN-SBF landing from both sides.Compared with SN and N-SBF,S-SBF is more difficult to trigger the convection because of the poor thermal conditions.Types of SBF depend largely on the direction of background wind.S-SBF occurs when background wind is northeasterly,N-SBF occurs when background wind is southerly and southwesterly,SN-SBF occurs when background wind is westerly.During the SBF-triggering convection days,Shanghai is under the control of a 500 hPa subtropical high.At 700 and 850 hPa southwesterly wind increases warm and humidity,promoting stratification instability.Westerly wind is rather weak at 925 hPa.PWV and K index are much greater at convection-induced days than convection-free days.
Keywords：sea breeze frontconvectionDoppler radarstatistical characteristicspatial and temporal distributioncirculation background
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：10( 644-653 )