【摘要】 在对夏季青藏高原上中尺度对流系统(MCS)进行自动追踪的基础上,利用环境物理量场数值格点预报资料(HLAFS),运用空间聚类中的CLARANS法对东移出高原的MCS环境场进行了挖掘和分析,获得了在青藏高原地区大气低层MCS热力场(温度场、湿度场和水汽通量散度场)和动力场(涡度场、散度场和垂直速度场)的空间分布特征,从而揭示了有利于MCS形成、发展和东移出高原的动力和热力学条件。MCS环境场中的散度场、垂直速度场以及水汽通量散度场空间分布特征的变化是MCS发展、演变的重要影响因素,这为夏季青藏高原上MCS发生、发展的动力及热力学机制的研究,以及高原上MCS移动路径的预测提供了一种全新而有效的方法。更多还原

【Abstract】 Firstly,the trajectories of Mesoscale Convective Systems(MCS) over the Tibetan Plateau from June to August 1998 were automatically tracked.Based on these,CLARANS method,as an effective spatial clustering method,is applied to mining and analyzing the environmental physical fields which influence MCS moving eastward out of the Tibetan Plateau in summer,using the High Resolution Limited Area Analysis and Forecasting System(HLAFS) data.The spatial distribution features of thermodynamic field(temperature field,humidity field and relative water vapor flux divergence field) and dynamical field(vorticity field,divergence field and vertical velocity field) around MCS at the low layers over the Tibetan Plateau are obtained to reveal the dynamical and thermodynamic conditions favoring the origination,development and trajectories of MCS.And,the results indicate that the changes of the spatial distribution features of divergence field,vertical velocity field and relative water vapor flux divergence field around MCS are key factors influencing the development of MCS.These prove an effective method to study the dynamical and thermodynamic causes of MCS origination and development,and predict the trajectories of MCS over the Tibetan Plateau in summer.更多还原