东亚与南亚雨季对流和层云降水云内的温湿结构特征分析

为认知降水云内的大气温湿结构特点,本文利用1998至2012年热带测雨卫星的测雨雷达(TRMM PR)和全球探空数据集(IGRA)的探测结果,融合计算获得了一套大气温湿廓线和降水廓线的准时空同步资料,并利用该融合资料研究了雨季东亚和南亚降水云内的温湿结构和不稳定能量特点。个例研究结果表明深厚对流降水表现出整层大气湿润、高空风速小的特点,层云降水则表现出850 hPa以下大气湿润、水汽随高度升高显著减少、高空风速大的特点。统计结果表明东亚季风区降水强度更大,对流和层云降水的回波顶高度分别可达17 km和12 km;南亚季风区降水强度较弱,回波顶高度比东亚约低1 km;统计结果还表明南亚季风区对流活动受季风推进的影响显著。两个季风区降水云团内的温度结构差异主要出现在近地面,南亚的近地面温度比东亚约高4℃,南亚对流降水云内的大气较东亚更干燥;整个雨季南亚降水的对流有效位能(CAPE)要大于东亚。本研究结果为模式模拟降水云温湿结构提供了观测依据。

The Vertical Characteristics of Temperature and Humidity Inside Convective and Stratiform Precipitating Clouds in the East Asian Summer Monsoon Region and Indian Summer Monsoon Region

To reveal the nature of the vertical structure of temperature and humidity inside precipitating clouds, a quasi-spatiotemporal synchronization dataset of temperature and humidity profiles, collocated with precipitation profiles, is generated in this study by merging Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and the Integrated Global Radiosonde Archive (IGRA) from 1998 to 2012. Based on this dataset, the characteristics of precipitation, temperature, humidity and convective available potential energy (CAPE) in the East Asian Summer Monsoon (EASM) region and Indian Summer Monsoon (ISM) region are investigated. Case studies indicate wet air in the atmospheric column inside deep convective precipitating clouds, together with weak wind in the upper atmosphere;while for stratiform precipitating clouds, wet air occurs below the layer of 850 hPa, accompanied by decreasing humidity and strengthening wind with height. Statistics illustrate a heavier precipitation intensity in the EASM region than in the ISM region, and the heights of storm tops can reach 17 km and 12 km for convective and stratiform precipitation, respectively, in the EASM region. Usually, the height of storm tops in the ISM is 1 km lower than that in the EASM region. Moreover, results also indicate that convective precipitation in the ISM is greatly impacted by the propagation of the monsoon. The significant difference of temperature for the precipitation scenario between the EASM region and ISM region also appears near the surface, i. e. about 4℃ higher in the ISM than in the EASM region. Generally, relative dryer air occurs inside convective precipitating clouds in the ISM region, as compared to in the EASM region, and there is a larger CAPE precipitation scenario in the ISM region than in the EASM region.