1986-2015年6月上海虹桥机场低云日数的年际变化及原因分析
投稿时间: 2017-03-01  最后修改时间: 2017-06-13  点此下载全文
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金耀廷 民航华东空管局气象中心, 上海 200335  
刘海文 中国民航大学 空中交通管理学院, 天津 300300 hwliu@lasg.iap.ac.cn 
杜梦醒 中国民航大学 空中交通管理学院, 天津 300300  
苗家瑞 中国民航大学 空中交通管理学院, 天津 300300  
基金项目:国家自然科学基金资助项目(91337215;41475051);四川省科技计划项目应用基础研究项目(2015JY0109);中国民航大学科研启动基金项目(2016QD05x)
中文摘要:利用1986-2015年上海虹桥机场低云资料、ERA-Interim再分析资料以及NOAA海面温度资料,对虹桥机场6月低云日数的年际变化进行了研究,并对导致其年际变化的原因进行了探讨。结果表明:虹桥机场低云在6月出现的天数最多,且6月低云日数具有显著的年际变化特征。影响虹桥机场6月低云日数年际变化的主要原因是:当副热带西风急流位置异常偏北时,虹桥机场处于急流入口区右侧,异常的上升气流有利于虹桥机场上空出现低云;当东南季风异常偏强时,来自低纬的水汽和来自北方的偏北气流能够在长江中下游地区聚汇,使得虹桥机场上空低云日数偏多。此外,ENSO对虹桥机场6月低云日数的年际变化具有重要影响。赤道中太平洋异常偏冷时,其上空的局地对流活动受到抑制,导致西北太平洋低纬地区对流层低层出现异常反气旋,该异常反气旋通过局地的风-蒸发-海面温度的正反馈过程得到增强,并在前期冬季形成后能够一直维持至6月,该异常反气旋有利于来自海洋的水汽在其南部偏东气流的输送下到达长江中下游地区,导致长江中下游地区降水偏多,有利于虹桥机场低云日数偏多。
中文关键词:上海虹桥机场  低云日数  年际变化  海面温度
 
Interannual variation of June low cloud days at Shanghai Hongqiao Airport during 1986-2015 and its causes
Abstract:The change of low cloud(cloud base height below 450 m) has great effect on the take-off and landing of the aircraft.Based on the low cloud cover data provided by Shanghai Hongqiao Airport(SHA),ERA-Interim reanalysis data and sea surface temperature(SST) data provided by NOAA during 1986-2015,this paper investigates the interannual variation of the low cloud days at SHA in June and its possible physical mechanism.Results show that the low cloud days are the largest at SHA in June,and the low cloud days in June have significant interannual variation.The main reasons affecting interannual variation of the low cloud days at SHA in June are that:When the subtropical westerly jet moves northward,SHA is located on the right side of jet entrance area,where the abnormal updrafts are good for the occurrence of low cloud above SHA;When the southeast monsoon strengthens,the water vapors from the low latitudes and the air flows from the north converge in the middle and lower reaches of Yangtze River,which also increases the low cloud days at SHA.In addition,ENSO plays an important role in the interannual variation of the low cloud days at SHA in June.When the SSTs in the tropical central Pacific are cooler,the local convective activity will be suppressed,which leads to an anomalous anticyclone at lower troposphere in the low latitude region of the northwestern Pacific.The anomalous anticyclone is enhanced continually by the local wind-evaporation-SST positive feedback process,and can persist from preceding winter to June.Hence,the vapor from the ocean can be transported by the easterly wind in the south of the anomalous anticyclone to the middle and lower reaches of Yangtze River,which can lead to more precipitation in the region and be beneficial to more low cloud days at SHA.
keywords:Shanghai Hongqiao Airport  low cloud days  interannual variation  sea surface temperature
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