热带测雨卫星测雨雷达探测的亚洲夏季积雨云云砧

The cumulonimbus incus in summer Asia as detected by the TRMM PR.

中文关键词:  热带测雨卫星, 测雨雷达, “其他”类型降水， 积雨云云砧

英文关键词:TRMM, Precipitation radar, “Other” type precipitation, Cumulonimbus incus

中文摘要:

      热带测雨卫星(TRMM)测雨雷达探测产品资料中“其他”类型降水一直被忽略，它具有什么物理含义也无从知晓。文中利用个例分析和统计分析方法，对10年夏季亚洲“其他”类型降水进行了研究。个例分析结果表明“其他” 类型降水的平均廓线表现了积雨云云砧特征，其廓线峰值(约0.6—1.0 mm/h)高度位于8—10 km，且云砧顶部具有0.8以上的可见光平均反射率和低于215 K远红外平均亮温；根据个例中积雨云云砧廓线特点，文中定义5 km以上各层累计降水率大于1 mm/h为云砧廓线，对亚洲夏季积雨云云砧样本进行了统计，结果表明该地区夏季云砧样本占“其他”类型降水样本总数的近70%；统计结果还表明夏季亚洲积雨云云砧出现频次为0.1%—0.4%，它至少超过对流降水频次的十分之一，亚洲云砧出现频次的特点是陆面高于洋面；云砧的结构特点表明云砧平均厚度3—4 km，其底部高度约6 km，顶部高度在10—12 km；云砧的平均可见光反射率在0.8—0.9，远红外平均亮温低于220 K。

英文摘要:

      The precipitation type of “others” defined in the algorithm of the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar has not been attached importance to for long time. So it’s unknown what their physical significances are. Based on cases analysis and statistics analysis, the “others” precipitation in summer Asia of the last ten years was investigated. The case analyses indicate that the profiles of the “others” show the shape of cumulonimbus incus with the profile peak (about 0.6-1.0 mm/h) appearing at the altitude of 8-10 km, together with the mean reflectivity over 0.8 and mean infrared brightness temperature below 215 K. According to these features of cumulonimbus incus profiles, statistics on cumulonimbus incus is performed with the accumulative total rain rate greater than 1 mm/h above 5 km altitude defined as the incus profile in this paper. The results reveal that the cumulonimbus incus samples are near 70% of the total samples of “others” type with their occurring frequency ranging from 0.1% to 0.4% in summer Asia, which is at least in excess of a tenth of the convective precipitation frequency therein. The results also show that the frequency of cumulonimbus incus over land is greater than that over ocean. Generally, the averaged thickness of cumulonimbus incus is about 3-4 km with its bottom located at 6 km altitude and its top altitude of about 10-12 km. The statistical calculations indicate that the mean reflectivity for such cumulonimbus incus is from 0.8 to 0.9 with the mean infrared brightness temperature below 220 K.