夏半年新疆K指数特征及其在短时强降水预报中的应用  

Characteristics of K Index in Summer Half Year in Xinjiang and Its Application in Short-term Heavy Rainfall Forecast

作　　者：张萌 李如琦 马玉芬[2] 李海花 ZHANG Meng;LI Ruqi;MA Yufen;LI Haihua(Xinjiang Meteorological Observatory,Urumqi 830002,China;Institute of Desert Meteorology,China Meteorological Administration,Urumqi 830002,China)

机构地区：[1]新疆气象台,新疆乌鲁木齐830002 [2]中国气象局乌鲁木齐沙漠气象研究所,新疆乌鲁木齐830002

出　　处：《沙漠与绿洲气象》2021年第5期8-15,共8页Desert and Oasis Meteorology

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0102);新疆气象局重点研究项目(ZD201902);国家重点研发计划“重大自然灾害监测预警与防范”专项(2019YFC1510501)。

摘　　要：利用1989—2018年4—9月高空探测和常规地面观测资料,计算新疆12个探空站的K指数气候平均值,采用线性趋势法、Mann-Kendall趋势检验法、R/S分析法等,分析新疆夏半年K指数时空分布特征,归纳其在新疆短时强降水中的预警阈值。结果表明:(1)新疆K指数总体呈西高东低分布,西部大气比同纬度其它地区更不稳定;(2)08和20时的K指数趋势特征基本相同,年平均值波动幅度较大,月平均值4月最小、7月最大;(3)近30 a克拉玛依、乌鲁木齐、库车、库尔勒站大气不稳定性呈增大趋势,其余站均趋于稳定;(4)短时强降水前K指数均>20℃,但月变化差异明显,随着月份的递进K指数呈先增大后逐渐减小的趋势;(5)以25%百分位作为短时强降水预报的预警阈值参考,4月的K指数阈值最小,为23.3℃,5、6、9月较为接近,在27℃左右,7—8月最大,29℃左右,北疆各站点发生短时强降水的K指数阈值区间为25.8~30.4℃、南疆为28.5~32.0℃、东疆哈密为29.5℃。Based on the upper-sounding data and conventional surface observation data from April to September in 1989-2018,the climatic average values of the K index of 12 stations in Xinjiang were calculated.Linear trend method,Mann-Kendall trend test method and R/S analysis method were used to analyze K index′s spatial and temporal distribution characteristics of summer half year of Xinjiang,and the early warning threshold of K index in short-term heavy rainfall in Xinjiang was summarized.The results are shown as follows:(1)The K index of Xinjiang is generally high in the west and low in the east,the atmosphere in the west is more unstable than that in other regions at the same latitude;(2)The trend characteristics of K index at 08:00 and 20:00 are the same.The annual average value fluctuates greatly.The monthly average value is the smallest in April and the largest in July.(3)The atmosphere in the stations of Karamay,Urumqi,Kuqa and Korla are gradually unstable in the past 30 years,while other stations tend to be more and more stable;(4)The K index was basically greater than 20℃before the short-term heavy rainfall,but the monthly variation was significantly different.The K index increased first and then decreased gradually from April to September;(5)25%percentile is taken as the early warning threshold of short-term heavy rainfall forecast,the K index threshold in April is the smallest,which is 23.3℃,the threshold value in May,June and September is relatively close,around 27℃,and the largest from July to August,about 29℃.The threshold range of the K index for short-term heavy rainfall at various stations ranges from 25.8 to 30.4℃in northern Xinjiang,28.5-32.0℃in southern Xinjiang,and 29.5℃of eastern Xinjiang.

关 键 词：K指数 时空分布 短时强降水 预警指标 

分 类 号：P457.6[天文地球—大气科学及气象学]