【摘要】 应用河西走廊敦煌、酒泉、张掖、民勤四站2006—2015年5—10月逐日07:00(北京时,下同)和19:00探空资料,分析0℃层高度的变化特征,以及与干湿、降水、灾害天气的关系。结果表明:0℃层高度与日极端气温、0 cm最低地温关系最为密切,日极端气温地温越高,0℃层高度越高,在19:00相关性最好,系数大于0. 95;温度露点差(T-Td)值与日降水量、日最低气温和0 cm最低地温成反相关,而与气温日较差成正相关,最大相关系数大于0. 7。河西0℃层高度在3300～5000 m,气压在680～560 h Pa,T-Td在10～17℃,早上低而湿,夜间相反。干湿天气对比中,干天气时0℃层高度高且早晚变化明显,19:00较高;而湿天气时T-Td早晚变化明显,07:00较小。有降水时,0℃层高度在3000～4800 m,气压在750～570 h Pa,T-Td<8℃,07:00 T-Td<6℃;昼夜变化中夜间降水07:00高度低,而白天降水19:00高度低。不同降水量级中,T-Td从小到大为大雨、中雨和小雨,相应最大值分别为2℃、5℃和9℃。雷暴0℃层高度在3600～4900 m,气压在660～560 h Pa,T-Td≤7℃。风沙天气0℃层气压在700～540 h Pa,沙尘暴0℃层高度7—9月07:00明显较高,7—8月达5000 m以上;沙尘暴天气出现时早上干而夜间湿,19:00 T-Td<5℃,因而汛期沙暴多发生在午后且伴有降水。≥35℃高温天气0℃层高度在4600～5300 m,气压在570～530 h Pa,T-Td≥13℃。更多还原

【Abstract】 In order to provide reference for the forecast of disastrous weathers,based on daily sounding data at07:00( Beijing time,after the same) and 19:00 from May to October at four stations of Dunhuang,Jiuquan,Zhangye and Minqin over Hexi Corridor during 2006—2015,the variation characteristics of 0 ℃ isotherm height as well as its relationships with dry-wet,precipitation and disastrous weather were analyzed. The 0 ℃ isotherm height is most closely related to the daily extreme temperature,0 cm minimum ground temperature; the higher the extreme air temperature and ground temperature is,the higher the 0 ℃ isotherm height is,and the best correlation is between the 0 ℃ isotherm height and 0 cm minimum ground temperature at 19:00,the coefficient of which is greater than 0. 95. The value of temperature and dew difference( T-Td) is inversely correlated with daily precipitation,daily minimum air temperature and 0 cm minimum ground temperature,but is positively correlated with the daily temperature range,and the maximum correlation coefficient is greater than 0. 7. The 0 ℃ isotherm height over Hexi Corridor was 3300～5000 m,the atmospheric pressure was 680～560 hPa,the T-Td was between 10～17 ℃,the height was low and wet in morning,but which was opposite at night. In dry and wet weather contrast,dry weather 0 ℃ isotherm height was high,obvious morning-evening variation and higher at19:00,while the morning-evening variation of T-Td was obvious and more humid at 07:00 in wet weather. When precipitation occurred,the 0 ℃ isotherm height was 3000～4800 m,the atmospheric pressure was 750～570 hPa,T-Td <8 ℃,and T-Td < 6 ℃ at 07:00; in day-night variation,low 0 ℃ isotherm height occurred at 07:00 in nighttime rainfall,while which occurred at 19:00 in daytime precipitation. In different precipitation levels,the maximum values of T-Td from light rain,to moderate rain and heavy rain were 2 ℃,5 ℃ and 9 ℃,respectively.Thunderstorm 0 ℃ isotherm height was 3600～4900 m,the pressure was 660～560 hPa,T-Td≤ 7 ℃. In gale and sand-dust weather,0 ℃ isotherm pressure was 700～540 hPa,sandstorm 0 ℃ isotherm height at 07:00 from July to September was higher 300～500 m than that of gale and sand-dust,which was above 5000 m from July to August. When sandstorm occurred,it was dry at 07:00 but wet at 19:00 when T-Td< 5 ℃,so sandstorm in flood season often occurred in the precipitation afternoon. In daily maximum temperature ≥35 ℃ high temperature weather,0 ℃ isotherm height was 4600～5300 m,the pressure was 570～530 hPa,T-Td ≥13.更多还原