夏季云顶高于对流层顶事件对东亚天气型及上对流层-下平流层大气结构的影响

采用A-Train系列卫星的AURA/MLS水汽、温度资料,CALIPSO/CALIOP云物理资料,结合ECMWF气象再分析资料,分析了东亚地区云顶高于对流层顶事件(Cloud Top Above the Tropopause,CTAT)的区域分布,及其对上对流层-下平流层(Upper Troposphere and Lower Stratosphere,UTLS)水汽和温度结构的影响。结果表明:亚洲季风区的夏季CTAT发生率是30%~55%,为全球最强区域;东北亚的夏季CTAT发生率是15%~20%,为中纬度最强分布区。以CTAT为指标的合成结果表明:15~30°N的东亚-西太平洋UTLS,水汽呈"上干下湿"的异常分布,温度呈"上冷下暖"的异常分布,该结构与该区域热带气旋合成的结果一致,说明热带气旋是该区域CTAT形成的主要天气系统;35~50°N的东北亚UTLS,水汽呈"上干下湿"的异常分布,温度呈"上暖下冷"的异常分布,该结构与该区域温带气旋合成的结果一致,说明温带气旋是该区域CTAT形成的主要天气系统。

The effects of cloud top above tropopause events on the structures of the upper troposphere and lower stratosphere in summer over East Asia

Based on the satellite data of moisture and temperature from AURA/MLS,the cloud physical information from CALIPSO/CALIOP,and the reanalysis dataset of ECMWF/Interim,this paper studies the distribution of cloud top above the tropopause(CTAT) events and its effect on water vapor and temperature structures in the upper troposphere and lower stratosphere(UTLS) over East Asia.Results are as follows:1)The maximum frequency of CTAT(reaching 30%-55%) in boreal summer is located in Asian monsoon region.Meanwhile,the maximum frequency of CTAT in the mid-latitudes is located in Northeast Asia,exceeding 15%-20%.2)Based on the CTAT,the composite analysis suggests that there is an anomalous structure of "dry above-moist below" and "cold above-warm below" in UTLS along 15-35°N over East Asia-West Pacific,which is consistent with the composite analysis result based on the tropical cyclones.It means that the tropical cyclones are the main weather systems forming CTAT in this area.3)The composite analysis shows that there is an anomalous structure of "dry above-moist below" and "warm above-cold below" in UTLS along 35-50°N over Northeast Asia,which is consistent with the composite analysis result based on the extratropical cyclones,meaning that the extratropical cyclones dominate the formation of CTAT there.