中国长三角地区盛夏副热带高压触发局地对流天气分布及气象因子分析  

Analysis of the midsummer local convection distribution and weather factors under the control of the Western Pacific subtropical high in the Yangtze Delta region of China

作　　者：辛辰 漆梁波[1] 储海[1] XIN Chen;QI Liangbo;CHU Hai(Shanghai Central Meteorological Observation,Shanghai 200030,China)

机构地区：[1]上海中心气象台,上海200030

出　　处：《气象与环境学报》2023年第4期57-64,共8页Journal of Meteorology and Environment

基　　金：上海市科学技术委员会科研计划项目“台风精细化降水网格预报应用技术研究”(19dz1200102)资助。

摘　　要：应用红外云图亮温阈值法判断对流云团,统计分析2015—2019年中国长三角地区盛夏副热带高压(副高)控制下的局地对流天气时空分布。结果表明:副高触发的对流天气频次日变化为午后单峰型,对流天气的高频区位于大城市附近、江南丘陵地区以及水陆交界处,而江河湖面、峡谷和盆地较少。副高偏南型的对流天气高频区位于山区和沿海地区,其低层处于有利于下垫面加热的偏西风场;副高偏北型高频区位于内陆,其低层的东风降低了沿海地区的下垫面温度,对流触发频率较小。不同对流参数的统计表明,对流有效位能对局地对流天气的触发有较明显参考。沿海地区的副高偏南型对流有效位能略高于副高偏北型,内陆地区相反。副高偏南型各站的抬升指数和抬升凝结高度均较低,表明该类型天气的不稳定性较强。This paper statistically analyzed spatial-temporal distribution features of triggered local convective weather under the control of the Western Pacific subtropical high(WPSH)in midsummer in the Yangtze Delta region from 2015 to 2019.The results show that the daily variation of the triggered local convection indicate a unimodal shape from noon to evening,and the high-frequency areas are located at the vicinity of large cities,the hilly areas,as well as the junction of water and land,but the convection rarely occurs over the rivers and lakes,canyons or basins.It is also found that high-frequency regions of the Southward type are mostly located in mountainous and coastal areas in the low-level westerly wind field,which is in favor to the surface heating.The high-frequency regions of the Northward type are located in inland,due to the low-level easterly wind weakening the surface heating and reducing the convection occurrence in the coastal area.The statistical analysis of the given convective parameters of two subtropical high types shows that the convective available potential energy(CAPE)value plays an obvious reference role in judging whether local convection is triggered.For coastal areas,the CAPE value of the Southward type is slightly higher than that of the Northward type,while it is opposite in inland areas.The lifting index(LI)and lifting condensation level(LCL)values of the Southward type are lower than that of the Northward type,reflecting intense stratification instability of the Southward type.

关 键 词：红外云图 对流有效位能 抬升指数 抬升凝结高度 

分 类 号：P468[天文地球—大气科学及气象学]