Characteristics of Easterly Low-Level Jet over Tarim Based on Encrypted Radiosonde Observations
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(06:00 UTC and 18:00 UTC)than those observed at routine radiosonde observation times(00:00 UTC and 12:00 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 was as high as 83.3％.In case of any TELLJ in southern Xinjiang,there would be a tendency of broader spatial distribution and higher intensity of precipitation.It could be concluded that the spatial structure of TELLJ and its contribution to catastrophic weather events such as heavy rainfall and severe convective phenomena differ distinctly from those in China's monsoon regions.This study can deepen the understanding of low-level jets in arid regions and provides references for disaster prevention and mitigation in southern Xinjiang,China.
万方数据
维普
