Atmospheric boundary layer heights estimated from radiosonde observations in theQinghai-Tibet Plateau and its downstream areas

The purpose of this study is to investigate the characteristics of atmospheric boundary layer (ABL) height in the Qinghai-TibetPlateau (QTP) and its downstream areas. Using the measurements of three radiosonde intensive observation field experiments, the convectiveboundary layer (CBL) and stable boundary layer (SBL) heights are determined with the parcel method and Richardson number method, respectively.The results show that CBL structures appear more frequently in the central QTP than in the eastern QTP and its downstream areas,and SBL structures appear more frequently in the Sichuan Basin than in the QTP and the middle Yangtze River Valley (YRV). The CBLheights in the central and eastern QTP are higher in spring than in summer, and the CBL height in the central QTP is higher than that in theeastern QTP. In the Sichuan Basin and middle YRV, the CBL heights are higher in summer than in winter, but the opposite is true for theeastern QTP. Moreover, the CBL height in the Sichuan Basin is lower than that in the middle YRV. For SBL situations, the SBL height in theQTP is higher in spring than in summer. In winter the SBL height in the Sichuan Basin is higher than those in the eastern QTP and middleYRV, and in summer the SBL height in the middle YRV is higher than those in the eastern QTP and Sichuan Basin. The SBL height differencebetween summer and winter is larger in the middle YRV and smaller in the eastern QTP, while it in the Sichuan Basin is in between. Inthe eastern QTP and its downstream areas, the mean ABL height is larger in daytime and smaller at nighttime; meanwhile, in the central QTP,it is small at sunrise and then increases till nighttime. Furthermore, the