台风“烟花”(2106)期间江苏南通地区降水稳定同位素组成变化特征及影响因素

Variation Characteristics and Influence Factors of Stable Isotope Composition of Precipitation in Nantong Area of Jiangsu,China During Typhoon In-Fa(2106)

2021年第6号(2106)台风“烟花”是我国有监测记录以来对大陆影响时间最长的台风,为华东地区带来了暴雨级的降水。基于台风“烟花”(2106)影响江苏南通地区期间小时尺度高分辨率的降水稳定同位素数据,分析了降水稳定同位素组成变化特征及影响因素。结果表明:降水δ^(18)O值为-11.7‰~-2.3‰,加权平均值为-7.4‰。台风影响前期,采样点水汽主要来源于附近海域,受云下蒸发效应的影响,降水δ^(18)O值相对偏正;台风影响中期,受相对湿度与上游累积对流强度的共同控制,降水δ^(18)O值逐渐偏负。但相较于已发表的我国台风降水δ^(18)O极端偏负值(-20.1‰~-12.6‰),台风“烟花”(2106)降水δ^(18)O极值并未显著偏负,主要是由于上游累积对流降水历时较短以及台风登陆后水汽缺乏大规模有组织性的对流活动。

Typhoon In-Fa(2106),the 6th typhoon in 2021,is one of the longest typhoon affecting China's Mainland since the beginning of monitoring records,resulting in torrential rain in East China.Based on hourly high-resolution precipitation stable isotope records during typhoon In-Fa(2106)in Nantong area of Jiangsu,the characteristics of stable isotope variation of precipitation and its influencing factors were analyzed.The results show that the δ^(18)O values of precipitation in Nantong area range from -11.7‰ to-2.3‰,with the weighted mean of -7.4‰.At the early stage of typhoon,water vapor originates primarily from the nearby sea area;due to the influence of sub-cloud evaporation effect,the δ^(18)O values of precipitation are relatively enriched.At the middle stage of typhoon,the δ^(18)O values gradually shift toward negative values under the combined control of relative humidity and the upstream cumulative convective intensity.There is no significantly negative δ^(18)O value of typhoon In-Fa(2106)precipitation compared with previously published extreme negative δ^(18)O values(-20.1‰to-12.6‰)of typhoon precipitation in China.This is mainly attributed to the short duration of upstream cumulative convective precipitation and lack of large scale organized convective activities of water vapor after typhoon made landfall.