论文部分内容阅读
利用1996-2010年逐时红外云顶亮温(TBB)数据,对青藏高原(下称高原)和东亚地区暖季(3-9月)中尺度对流系统(MCSs)进行了普查,获得MCSs各项特征数据集；结合CMORPH降水资料对MCSs降水特征进行了分析,在此基础上又对高原和东亚地区的MCSs特征进行了对比分析.结果表明:(1)高原是东亚地区MCSs高频发生区域,高原MCSs的平均发生频次远高于东亚25°N以北地区,是东亚25°N以北地区唯一的MCSs活动高频区.高原腹地是高原地区MCSs发生的高频区,在31°N,88°E附近MCSs的发生频次最高.(2)高原地区 MCSs分布有明显的月际变化,春季主要出现在高原北部,夏季主要出现在高原中东部和南部.高原地区MCSs的月际变化特征与东亚地区基本一致,东亚夏季风是其月际变化的重要影响因子.(3)高原地区MCSs存在明显的单峰型日变化特征,但春、夏季日变化特征略有不同,高原MCSs的日变化较东亚地区更为显著.(4)高原地区MCSs的降水频次为5.6％,降水贡献率为10.1％,最大降水频次为12％,最大降水贡献率为27％；与东亚地区相比,高原的MCSs降水偏小.(5)高原地区的MCSs大多为向东移动且移速缓慢以及短生命史的MβCS,平均生命史为4.6h,平均面积约为11.2×10-1km2,平均移速为31.5 km·h-1,东移的MCSs占59.4％；与整个东亚地区的MCSs相比,高原的MCSs面积和尺度都较小,生命史略短且移速慢,云顶平均TBB和平均最低TBB均偏高.“,”Based on the hourly equivalent temperature of black body (TBB) data of GMS-5,FY-2C and FY-2E from 1996 to 2010,the mesoscale convective systems (MCSs) in warm season (from March to September) over the Qinghai-Xizang Plateau (QXP) and East Asia regions were investigated.The results show that:(1) The QXP is one of the high-frequency area of MCSs in East Asia,where is higher average frequency in East Asia to the north of 25°N.The hinterland of the QXP is the high-frequency concentration area of MCSs,and its nearby (31°N,88°E) is the highest frequency area.(2) There are obvious monthly variation characteristics of MCSs over the QXP,that the MCSs often occur in the northern and eastern areas of the QXP in spring and in the middle-eastern and southern areas in summer.The monthly variation in the QXP is similar with that of East Asia,and the summer monsoon of East Asia is the important factor.(3) The daily variation of MCSs over the QXP appears single peak distribution,but there are a few differences between spring and summer,that daily variation of MCSs over the QXP is more obvious than eastern Asia in some respects.(4) The precipitation frequency ofMCSsis5.6％,the contribution rate of precipitation is 10.1％,the frequency of maximum MCSs precipitation is 12％ and the contribution rate of maximum MCSs precipitation is 27％.Comparing with the East Asian region,MCSs precipitation in the QXP is smaller.(5) The most of MCSs over the QXP are eastward low-speed and short life cycle MβCS.The average life cycleof MCSis4.6 h with 11.2×10-1 km2 of average area,whose average speed is 31.5 km·h-1 and 59.4％ of them are eastward.Comparing with the MCSsin East Asian,the MCSs over the QXP show the different characteristics:Smaller scale and area,shorter life cycle,lower speed,and average TBB and average lowest TBB are highter.