四川盆地低空飞行飞机积冰的气象条件分析

Analysis of Weather Conditions for Aircraft Icing in Low-Level Flight in Sichuan Basin

利用常规气象资料和机载温度探测资料(OAT),对2015—2016年冬季四川盆地7次低空飞行(3000m以下)飞机积冰的个例进行了诊断分析。结果表明:冬季在四川盆地内3000m以下飞行,导致飞机积冰的环流形势包括冷锋型、低槽型、西南气流型以及弱脊型,其中前三种形势更有利于中度积冰的产生。飞机积冰均发生在穿过温度小于0℃的云中,出现中度积冰的温度范围在-4^-2℃,轻度积冰温度范围在-1~0℃,在这一温度范围内,相对湿度越大越有利于积冰的产生,其中产生中度积冰时相对湿度均在90%以上。在有利的环流形势以及一定的温度和相对湿度条件下,垂直上升气流速度在-1.0^-0.05Pa·s-1之间更有利于中度积冰的产生,-0.05~0Pa·s-1之间更有利于轻度积冰的产生。

Weather conditions for airplane icing and icing characteristics in the low level flight are analyzed on the basis of the FNL data,with the temperature measurements（OAT）and observations from 7 icing reports during the winters of 2015 and 2016.The results show that when the plane flies at the low levels in the winter in the Sichuan Basin,there are four types of circulations conductive to aircraft icing,including cold front,low trough,the southwest flow and weak ridge type,and the former 3 types are more beneficial to moderate icing.The seven cases show that the aircraft icing was formed in the clouds with the temperature below zero;the moderate icing formed in the temperature range of-2 to-4 ℃;the light icing was in the range of 0 to-1 ℃.Besides,the greater the relative humidity was,the more conductive to the formation of ice,and the moderate icing is more likely formed when the relative humidity is more than 90%.Under the beneficial circulation background and certain scope of temperature and relative humidity,the updraft speed between-0.05 to-1.0 Pa爛s-1 is more conducive to moderate icing,while the range of 0 to-0.05 Pa爛s-1 is more conducive to mild icing.