大气低频系统与华南强降水过程的研究

Study of Atmospheric Low-Frequency System and Strong Precipitation Processes in Southern China

使用NCEP/NCAR格点资料和华南地区主要站的降水资料,根据华南地区汛期强降水过程的大气低频系统(低频气旋和低频反气旋)的地理位置和相互配置,建立了华南地区汛期(4—9月)大气低频系统延伸期(10~30天)强降水过程预测模型,并在2013—2014年汛期值班应用。结果表明,该模型可以提前10~30天预报华南地区强降水过程。该模型准确预测了2014年华南入汛的首场强降水过程,此次过程在低频天气图上反映明显。同时,还对低频和非低频天气系统的天气学、动力学意义进行了分析,指出低频系统能反映出非低频系统,二者是相互联系的,都反映出南、北气流在华南地区的辐合,从而引起强降水过程,而且二者都与斜压能量转换和低频波列的活动有关。

Based on the NCEP/NCAR grid point data and precipitation data of southern China area,and the geographical location and mutual disposition of low-frequency system（ low-frequency cyclones and anticyclones）,the paper study and establish a low-frequency system based prediction model,which aim at heavy precipitation events of southern China area in extended-range（ 10 ~ 30 days） during flood season. The application of 2013—2014 flood season shows that the model can forecast heavy precipitation events of southern China area 10 ~ 30 days in advance. The model accurately forecasted the first heavy precipitation event of southern China in 2014 flood season,which is well reflected on low-frequency synoptic chart（ LFSC）. Synoptic and dynamic significance of weather systems on low-frequency synoptic chart and live weather chart is also analyzed,and it is pointed out that low-frequency system can reflect live weather system,the two are interrelated and reflects convergence of north and south airflowin the southern China,which therefor cause strong precipitation process,also the two are both associated with the conversion of baroclinic energy and activity of lowfrequency wavetrain.