通过融合热带测雨卫星(TRMM)测雨雷达和可见光/红外扫描仪十年的探测结果,利 用PR对降水云的直接识别,分析研究了夏季热带和副热带地区降水云及层状降水云和对流降水云的 可见光0.63 μm与红外10.8 μm通道信号的气候特征。研究结果表明热带辐合带(ITCZ)、南半 球辐合带(SPCZ)、亚洲季风区、热带非洲、北美及南美热带地区降水云的0.63 μm通道平均反 射率均大于0.5,最大平均反射率可达0.7以上,且降水云平均反射率在陆面高于洋面；热带和副 热带非降水情况的0.63 μm通道的平均反射率量值变化于0.1～0.4之间。夏季热带和 副热带95%以上的对流降水平均反射率超过0.5,而只有50%层云降水的平均反射率超过0.5。夏季 亚洲季风区、ITCZ、SPCZ、热带非洲降水区域的10.8 μm通道平均辐射温度低于250 K,而非降水情 形的平均辐射温度高于280 K;热带非洲、青藏高原、中美洲及热带东太平洋对流降水的10.8 μm通道平均 辐射温度多低于230 K,而在东北和东南太平洋、北部非洲和南部非洲、南美陆面的大部分地区层云降水 该通道的平均温度在280～290 K之间。研究结果还表明降水情形下,热带东半球热辐射温度 比西半球温度偏低约10 K,相应东半球的0.63 μm通道平均反射率也高于西半球。

Climatological characteristics of visible and infrared scanner(VIRS), mainly at channel 0.63 μm and 10.8 μm, from precipitating clouds including stratiform and convective precipitation in summer from 1998 to 2007 over the tropics and subtropics are investigated based on combining measurements of VIRS and tropical rainfall measuring mission (TRMM) precipitation radar(PR) together with the precipitating cloud identification of PR detections. Results indicate the distributions of more than 0.5 mean reflectivity at channel 0.63 μm for precipitating clouds located in the intertropical convergence zone (ITCZ), southern Pacific convergence zone (SPCZ), Asian monsoon region, tropical Africa, North America and southern tropical America. The maximum mean reflectivity over these regions is over 0.7. Generally, the mean reflectivity of precipitating clouds over land is larger than that over ocean. On the contrary, the mean reflectivity for non-precipitating circumstance over the tropics and subtropics only varies from 0.1 to 0.4. For 95% convective precipitation, its mean reflectivity is over 0.5 against only 50% stratiform precipitation with such mean reflectivity. At channel 10.8 μm, the mean radiant temperature lower than 250 K appears in the precipitation regions over Asian monsoon, ITCZ, SPCZ and tropical Africa accompanying with higher than 280 K in non-precipitation regions. The mean radiant temperature of most convective precipitation at channel 10.8 μm is lower than 230 K over the tropical Africa, Tibet plateau, the central America and eastern tropical Pacific Ocean while that of most stratiform precipitation varies from 280 to 290 K over the northeast and southeast Pacific, North Africa, South Africa and most parts of South America. Moreover, the radiant temperature of precipitation cloud over the eastern hemisphere is 10 K higher than that over the western hemisphere coincidently with the higher reflectivity at channel 0.63 μm in the eastern hemisphere.