摘要
塔里木东风低空急流位于中国西北干旱区,是造成新疆沙尘暴、暴雨、强对流等灾害性天气的直接影响因素。研究塔里木东风低空急流,一般基于每日两次的常规观测资料,时间分辨率较粗,不能完整反映其特征。本文利用2022年5月1日至30日新疆首次开展的大范围加密探空观测资料,揭示塔里木东风低空急流的精细特征及其与南疆降水的关系。结果表明:(1)加密观测期间,共出现17个塔里木东风低空急流日(占总观测日数的56.7%);与常规探空观测时次(0000 UTC和1200 UTC)相比,两个加密观测时次(0600 UTC和1800 UTC)观测到的塔里木东风低空急流的总次数更多。(2)在6个加密观测站中,仅若羌、库尔勒和民丰观测到塔里木东风低空急流;在同一时次,最多观测到两个站点同时出现塔里木东风低空急流。(3)若羌站出现塔里木东风低空急流的次数最多,平均风速最大,平均急流高度最高,急流的强度等级最强;库尔勒站其次。塔里木东风低空急流在若羌站呈现明显的入夜加强,正午减弱的特征;在库尔勒站和民丰站的昼夜变化不明显。(4)2022年5月南疆70.0%以上的降水日中有塔里木东风低空急流,暴雨日中塔里木东风低空急流的出现率高达83.3%;有塔里木东风低空急流影响时,南疆的降水范围更广,降水强度更大。研究结果可加深对干旱区低空急流的认识,并为南疆防灾减灾提供参考。
Low-level jet typically refers to a strong and narrow air current existed in a boundary layer or lower troposphere.Low-level jet has a significant impact on global weather and climate.The easterly low-level jet over Tarim(hereinafter abbreviated as TELLJ)is formed in the arid region of northwest China,which plays a crucial role in creating regional catastrophic weather,such as sandstorms,heavy rainfall,and strong convection in Xinjiang.Past research on TELLJ primarily relies on routine twice-daily observational data with coarse temporal resolution,which cannot fully capture its behavior.In this paper,the fine features of TELLJ and its relationship with precipitation in southern Xinjiang was revealed by using the first-hand data of large-scale encrypted radiosonde observation conducted for the first time in Xinjiang from May 1 to May 30,2022,which included daily variation of TELLJ,and the differences in occurrence frequency,wind speed,height,and intensity between conventional and unconventional observation times.It found that(1)during the encrypted observation period,a total of 17 days with occurrences of TELLJ appeared,accounting for 56.7%of the total observation days;more occurrences of TELLJ was recorded at two encrypted observation times(0600 UTC and 1800 UTC)than those observed at routine radiosonde observation times(0000 UTC and 1200 UTC).(2)Among the six encrypted observation stations,only at Ruoqiang,Korla,and Minfeng,TELLJ was recorded;at the same observation time,TELLJ was observed simultaneously at most two stations.(3)TELLJ occurred frequently at Ruoqiang with the highest average wind speed,the highest average jet height,and the strongest intensity;and similarly at Korla it followed the pattern.At Ruoqiang,TELLJ exhibited a distinct pattern of strengthening at night and weakening around noon,whereas there was little diurnal variation at Korla and Minfeng.(4)In May 2022,during more than 70.0%of precipitation days in southern Xinjiang it could witness TELLJ,and the occurrence rate of TELLJ in heavy rains
作者
杨霞
何清
赵克明
苏亚乔
YANG Xia;HE Qing;ZHAO Keming;SU Yaqiao(Xinjiang Uygur Autonomous Region Meteorological Observatory,Urumqi 830002,China;Institute of Desert Meteorology,China Meteorological Administration,Urumqi 830002,China)
出处
《山地学报》
CSCD
北大核心
2023年第6期836-845,共10页
Mountain Research
基金
国家自然科学基金(42065001,42030612)。
关键词
东风低空急流
探空观测
降水
塔里木盆地
南疆
easterly low level jet
radiosonde observation
rainfall
the Tarim basin
southern Xinjiang
