夏季风爆发前后中国区域对流层顶高度变化特征

利用2008—2014年全国高垂直分辨率的L波段探空资料，统计分析了东亚夏季风爆发前后我国不同区域对流层顶高度变化特征。研究表明:夏季风爆发后，对流层顶高值区向北推进，最大值位于青藏高原南部及其东南部地区；对流层顶高度的向南梯度和向东梯度大值区均由爆发前的30°~40°N北移至40°~50°N；受地面加热和垂直运动的影响，中国东北部和中东部在夏季风爆发后对流层升温，平流层-对流层过渡层降温，大气温度梯度增加，对流层顶上升，其中中国东北部在夏季风爆发前，大气温度廓线为双峰结构，易出现双对流层顶，第一对流层顶较低；中国南部整层大气温度廓线在夏季风爆发后略有增加，对流层顶有所下降。

Characteristics of Tropopause Height over China During East Asian Summer Monsoon

Tropopause, as a transition layer between the troposphere and stratosphere, plays an important role on the regional and global climate and weather. Influenced by the Tibetan Plateau and monsoon, tropopause over China can even affect the global weather and climate, especially by changing aerosol distribution. Focusing on characteristics of tropopause height, 3 different sub regions are defined in China during the East Asian summer monsoon, using high vertical resolution sounding data from year 2008 to 2014 collected by the network of L band sounder. Results are shown as follows. Tropopause height increases with decreasing latitudes. The region with high tropopause moves northward with the maximum locating over the south of the Tibetan Plateau and the region to the southeast of the Plateau after the summer monsoon breaking. The region with large southward and eastward gradient of tropopause height moves from 30°-40°N to 40°-50°N after the summer monsoon break. There is little latitudinal difference in tropopause height over all the three sub regions, indicating that the topography has little influence. However, tropopause height changes greatly after summer monsoon breaking: In northeast China and central east China, the tropopause increases and in south China it slightly decreases. Influenced by the surface heat and vertical velocity, the temperature increases in the troposphere and decreases in the troposphere stratosphere transition layer, which results in an increasing vertical temperature gradient after the summer monsoon breaking over the northeast and central east China, resulting in higher tropopause. For northeast China, the temperature profile shows double peaks before the monsoon breaking, which is easy to form double tropopauses with a low first tropopause. In south China the temperature increases through the whole atmosphere after the summer monsoon breaking, generating slightly decreased tropopause. Limited by the coarse temporal resolution, more temporal characteristics such as daily changes cannot be studied. Further research should combine various datasets such as satellite to get a comprehensive analysis on the tropopause behavior over the mainland China.