高原降雨天气过程中总体输送系数的变化特征

以中日亚洲季风机制合作研究计划设在西藏的4个自动气象站（AWS）获得的近6年（1995年7月-1999年6月）观测连续、时次密集的近地层大气梯度观测资料为基础，选取了高原中、东部夏季雨季的一些典型降雨过程，应用廓线-通量法计算了这些站降雨过程中每隔20min一次的总体输送系数，分析了其随层结稳定度、地表粗糙度以及在降雨天气过程中的变化特征。结果表明：总体输送系数的变化与近地层大气层结稳定度、地表粗糙度具有确定的、密切的关系；总体输送系数对降雨天气过程有明显的响应，但在与降雨过程的雨量峰值、降雨时段的对应上，各站的规律性略有不同。

Characteristics of Bulk Transfer Coefficient in Precipitation Processes of Tibetan Plateau

On the basis of original data from four stations of AWS installed in Tibet in the observational periods of six years(from July 1995 to June1999), according to PRC-Japan Asian Monsoon Cooperative Research Program,some typical processes of rainfall in the Eastern Tibetan Plateau in rainy seasonKG*2are chosen, the bulk transfer coefficients every 20 minutes in those processesare estimated by using the profile-flux method, andrelationships in those rainfall processes between the bulk transfer coefficients and atmospheric stability in the surface layer, surface roughness length and rainfall amountare analyzed. The results show that therelations between bulk transfer coefficient and the atmospheric stability in the ground layer, surface roughness lengthare definite and close. The responses of bulk transfer coefficientsto the processes of plateau rainfall are remarkable, but the correlations to peak and period of rainfall processes are not identical in each station.