3D Structure of Rain and Cloud Hydrometeors for Typhoon Kujira(0302)
3D Structure of Rain and Cloud Hydrometeors for Typhoon Kujira(0302)
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发表时间：
2006
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通讯作者：
H. Hui;Cheng Ming;Zhou Feng
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作者：
H. Hui;Cheng Ming;Zhou Feng
热带气旋降水预报是一个重大挑战，由于缺乏高分辨率的台风结构资料，即探测台风内部云结构的技术限制，许多个例研究显示，热带气旋的降水结构相当复杂，且因个例而异。早期的雷达图像显示，台风气旋降雨通常是以螺旋状向风暴中心移动的雨带组织起来的，本文选取了2003年4月发生在巴布亚新几内亚北部开阔海面上的超强台风Kujira（0302）为例，在TRMM观测期间稳定增强，最大持续风速达到67米/秒。利用可见光和红外扫描仪（VIRS）研究了雨云中雨和水凝物的三维结构，降水雷达（PR）和TRMM微波成像仪（TMI）利用PR资料2A 23对降水类型进行了研究，结果表明：层状降水占降水面积的85.5%，降水贡献率为58.1%，对流雨的覆盖面积仅为13.1%，但对台风降水的贡献率为41.8%，对流雨的覆盖面积虽然较小，但对台风降水的贡献率很大，对流雨的平均雨率为19.78 mm/h，而层状云降水的降水量仅为4.22mm/h，前者约为后者的4.7倍，这一比值大于热带海区层状云降水和对流降水的平均比值（平均比值为3.3），利用2B 31资料分析了平均降雨量的分布，平均降雨量分布是以风暴中心到300公里的环形区域为单位计算的。结果表明，随着距台风中心距离的增加，降水量逐渐减少，60%左右的降水来自距台风中心100 km以内的区域，但该地区仅占用PR资料反演的2A 25资料研究了台风降水的垂直廓线，层状降水在不同高度上达到最大值对2A 12资料进行了分析，结果表明：台风中心50 km范围内的层状云降水最大值出现在5 km高度，其它地区的层状云降水最大值出现在4.5 km高度; 50 km范围内的对流降水率在3.0 km高度以下波动，其它地区的对流降水率随高度的减小而增大。结果表明，台风降水云中的水凝物随距台风中心距离的增加而减少，不同类型的水凝物在不同高度上达到最大值，降水云水主要分布在28 km高度，在5公里处达到最大值，大部分云冰位于距离台风中心100公里以内的区域，在100 ~ 200 km范围内，降水量在2km高度处达到最大值，在14 km高度处达到最大值，在7 km高度处达到最大值热带气旋降水的三维结构研究有助于提高热带气旋降水预报水平。
Predicting rainfall associated with tropical cyclones is a major challenge.Due to lack of high resolution data on typhoon structure,i.e.the technical limitation of detecting the cloud structure of inner-typhoon,it is difficult to further understand its dynamic transportation characteristics.A number of case studies have shown that the precipitation structures in tropical cyclones are quite complex and vary from case to case.Early radar images revealed that the typhoon cyclone rainfall is usually organized in bands spiraling toward the storm center,commonly referred to as rainbands.In this paper,the case of super Typhoon Kujira(0302) occurring in April 2003 is chosen.It is located over open water to the north of Papua New Guinea,steadily intensified during the period of TRMM observations and reaches a maximum sustaining wind of 67 m/s identified as class 4.The 3D structure of rain and hydrometeors in rain cloud is studied by use of Visible and Infrared Scanner(VIRS),Precipitation Radar(PR) and TRMM Microwave Imager(TMI) data.The rain type is studied by use of PR data 2A23.It is found that the stratiform rain covers 85.5% area and contributes 58.1% rainfall,the convective rain only covers 13.1% area but contributes 41.8% rainfall.Though the convective rain only covers smaller area of typhoon rain,it is important for the typhoon rainfall.At the same time,the average rain rate of convective rain is 19.78 mm/h,but is only 4.22 mm/h for stratiform rain.The former is about 4.7 times of the latter.This ratio is more than the average ratio for stratiform and convective over the tropical sea area(average ratio is 3.3).The mean rainfall distribution is analyzed by using 2B31 data,which is retrieved from combining of PR and TMI products.The mean rainfall distribution is computed using 5-km annulus from the storm center to a 300-km radius.It is found that the rain rate decreases as the distance from the typhoon center increases.It is about 60% rain which comes from the region within 100 km from typhoon center,but the region covers only 40% of the total typhoon rain area.The vertical profiles of rainfall are studied by using 2A25 retrieved from PR data.The stratiform rain reaches its maximum at different heights for the different distances from typhoon center.The maximum of stratiform rain appears at 5 km height in the region within 50 km from typhoon center and 4.5 km height over the other area.The convective rain rate fluctuates under 3.0 km height in the region within 50 km and increases as the height decreases over the other area.The hydrometeor profiles are studied by using 2A12 data,which are produced by combining models and TMI data.Hydrometeors in typhoon rain cloud decreases as the distance from typhoon center increases.The different types of hydrometeors in rain cloud reach their maximum values at different heights.Most rain cloud water is distributed at the heights of 28 km,and reaches its maximum at 5 km.Most cloud ice is located in the region within 100 km from the typhoon center,and reaches its maximum at 14 km height in this region and 7 km height in the other region.The precipitation water reaches its maximum at 2 km height within 100 km from the typhoon center,but the height increases to 4 km in the region 200 km out from center.Most precipitation ice is concentrated above 7 km height.The studies of the different types of rainfall and hydrometeors 3D structure for tropical cyclone should be helpful in improving the tropical cyclones rainfall forecasting.