摘要
中尺度对流系统(MCS)是夏季造成暴雨等灾害性天气的重要天气系统,高时空分辨率的静止卫星红外云图是监测MCS的主要手段之一。结合新疆的实际情况,将中-β尺度MCS的最小尺度定义为1.0～3.0个纬距。利用1998-2002年日本第5代地球静止气象卫星(GMS-5)逐时红外云图数字资料,采用红外云图增强和图像叠加处理技术,对发生在新疆的MCS进行了分析研究,给出了新疆MCS的地理分布特征和生命史特点。结果表明:(1)5 a内新疆没有出现中-α尺度MCS,出现了111个中-β尺度MCS。MCS具有年际不均衡性,1998、2000年为多发年,2002年为少发年。新疆有两个明显的MCS集中区,一处在伊犁河谷东边天山山脉的迎风坡,另一处在西天山东侧背风坡的柯坪附近,北部的古尔班通古特沙漠中MCS发生的很少,而南部的塔克拉玛干沙漠有MCS的活动。(2)MCS主要出现在春末和夏季,秋冬少见。6月最多,占总数的34%,其次是5月和7月,分别占总数的25%和15%,与新疆沙尘暴、冰雹等灾害性天气的高发季节相对应。(3)多数MCS形成于午后到午夜,夜间至凌晨消散,持续4～6 h,有明显的夜发性。发生在新疆的MCS维持时间较短,这与新疆水汽供应较少有关。(4)新疆MCS的形状规则,圆形和椭圆形各占一半。绝大多数MCS是由对流泡发展而成,尺度较小。(5)给出了3个发生在不同地区的MCS个例,用以展示新疆MCS在发生和发展过程及其云顶黑体温度分布上所表现出来的多样性。
Mesoscale convective systems （MCSs） can cause heavy rain and other severe weather events at summer. Satellite IR images with high spatial and temporal resolution is one of main approach to monitor behaviors of the MCSs. In present paper, the smallest scale of meso-^-scale was defined as 1.0 to 3.0 latitudes according to actual situation in Xinjiang. The hourly GMS -5 meteorological satellite infrared images data from 1998 to 2002 in Xin- jiang were processed by infrared satellite image enhancement and image overlay processing technology in order to analyze the behaviors of MCSs. The results showed as follows ： （ 1 ） in this five years, the MCS in meso-β-scale did not appear, the MCS in meso43-scale was happed 111 times. MCS has uneven characters： frequently occurs in 1998, 2000 while rare occurs in 2002. MCSs are concentrated in two major areas： one is the windward slop of Tianshan Mt. in the eastern of Ili River Vally, another Keping at the lee side of West Tianshan Mt. There occur less frequently in Gurbantunggut Desert while more in Taklimakan Desert ; （2） Most of MCSs occur at end of spring and the summer while it rarely occur at autumn and winter. In June, the number of occurrences of MCSs accounts for 34 % of the total while in May and July respectively 25 % and 15 %, this fact is related to the high incidence season of the severe weather such as duststorm and hail in this area; （3） Most of MCSs possesses nocturnal fea- ture, and it occurs from noon to midnight, and dissipates before dawn, the duration is 4 - 6 h ; （4） The shape of MCSs in Xinjiang consist of round and oval-shaped, and each of them is accounts respectively for 50 % of the to- tal. Moreover, the MCS is developed from the convection bubble, so scale of the majority of MCS is small; （5） the MCS example in different area reveals the diversity of blackbody temperature distribution in cloud top and MCS evo- lution process.
出处
《干旱区地理》
CSCD
北大核心
2012年第6期857-864,共8页
Arid Land Geography
基金
国家科技部公益性行业(气象)科研专项-沙漠及周边地区灾害性天气监测预报警报技术(GYHY201006012)
关键词
红外云图
中尺度对流系统
地理分布
生命史
infrared image
mesoscale convective system
geographic distribution
life cycle
