利用TRMM(Tropical Rainfall Measuring Mission)卫星降水雷达(Precipitation Radar,PR)资料对2005年8月发生在墨西哥湾的热带气旋卡特里娜(Katrina)初生、发展和变性3个阶段的层状云和对流云的近地面降水和降水垂直廓线进行分析.结果表明:在热带气旋的整个生命期,对流性降水个数约是层状云降水个数的四分之一;随着气旋的发展,对流性和层状云降水的平均强度逐渐增强,在登陆前有所减弱,登陆后对流性降水和总平均降水均增强,层状云降水稍有减弱;大部分降水廓线都随高度升高均呈现先略增大(到4 km高度)、再减小的趋势,在6～7 km处由于冻结层的存在使得降水达到最小值.%Tropical cyclone is a primary disastrous synoptic system in China. Its monitoring mainly depends on optical data, i. e. , visible and infrared data. These sensors observe the albedo and temperature of cloud top which is somewhat related with the precipitation, but leave the precipitation particles inside the precipitation-cloud system unseen. Fortunately, the microwave sensor can penetrate into the cloud and sense precipitation particles in and even below the cloud system, and observe precipitation more directly.Based on TRMM PR (Precipitation Radar) product, 6 orbit data in four days covering the main part of the cyclone are analyzed to study the characteristics of near-surface precipitation and vertical precipitation profile of stratiform and convective cloud in nascent, developing, and recessionary stages of the cyclone Katrina.Results indicate that the convective rain percent is 15％-22％ and stratiform rain occupies 78％-85％. The average stratiform rain rate is 2.7-5.9 mm · h-1 , the convective rain rate is 7.7-17.5 mm ·h-1 , and the total rain rate is 3.5-7.7 mm · h-1. During the life cycle of the cyclone, the pixel number with convective rain is one fourth of stratiforn one's, while the average intensity/rain rate of convective rain is four times of stratiform rain. The average rain rates of convective and stratiform precipitation gets larger along with the developing of cyclone, gets a little weaker just before landing, and enhances after landing except that stratiform rain become a little weaker.During nascent stage, weak precipitation of 1-2 mm · h-1 is dominant, and there are no pixels with rain rate larger than 31 mm · h-1. During developing stages, the rain rate intensifies. More rain pixels appear, some with very high rain intensity. After landing, because of the strong friction effects with land surface, the proportion of pixels with rain rate between 5-10 mm · h-1 increases, and the pixel number with rain is almost doubled except the ones between 30-50 mm · h-1 becoming a little less.During the nascent and recessionary stages, the max precipitation height is 10 km. During the developing stages, it reaches as high as 16 km. Most precipitation profiles vary first larger (to 4 km) then smaller with height, and reach minimum at 6-7 km because of the freezing level. The profiles of nascent and recessionary stages diminish equably with height. The profiles of developing stages vary very uneven with height because of the violent upwelling airflow in cyclone.The analyses on TRMM data provide a perception to precipitation type, horizontal distribution, and intensity of data-sparse oceanic tropical cyclone where conventional radiosonde measurements are not available. These results are useful information for future quantificational precipitation retrieval of cyclone.
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