1991—2020年韶关市“龙舟水”特征分析

An Analysis of the Characteristics of "Dragon-boat Precipitation" in Shaoguan from 1991 to 2020

利用1991—2020年韶关8个国家站和NCEP/NCAR逐日再分析资料,采用线性回归、Morlet小波分析、相关分析等方法,分析韶关"龙舟水"的时空分布特征.结果表明:1991—2020年韶关的"龙舟水"整体呈现出雨量、雨日增多、雨强增强的特点;"龙舟水"日雨量具有"前少后多"的特点,且后期有明显的突升突降特质;空间分布具有南多北少的特点,且突显出6个"雨窝点";异常偏多年500 hPa北半球高纬度地区呈现两脊一槽形势,东亚大槽北强南弱,副高偏弱偏东,850 hPa低纬度南支槽活跃,粤北风场辐合,偏少年则相反;"龙舟水"雨量与前汛期雨量有显著的正相关,与同期气温负相关.因此,研究"龙舟水"特征对韶关市防洪有一定意义.

Based on the 1991—2020 daily precipitation data of Shaoguan meteorological observations and the NCEP/NCAR daily reanalysis data,using Linear regression,Morlet wavelet analysis and correlation analysis,the spatial and temporal features of Dragon-boat precipitation are studied.The result shows that the Dragon-boat precipitation in Shaoguan during 1991—2020 shows the characteristics of increased rainfall,more rainy days,and enhanced rain intensity.The daily Dragon-boat precipitation is less in the early and more in the later period with sudden rise and fall,and is distributed more in the south and less in the north of Shaoguan,with occurring 6 rainfall centers.During more Dragon-boat precipitation,500 hPa high-latitude area in the northern hemisphere presents a situation of two ridges and one trough.The East Asian trough is stronger in the northern and weaker in the southern section,and the subtropical high is weaker and shifts eastwards.Besides,the southern branch trough in the 850 hPa low-latitude area is active and there is wind convergence in the northern area of Guangdong.But such features are opposite in the year of less Dragon-boat precipitation.Last but not least,the amount of Dragon-boat precipitation has a positive correlation with that during annually first rainy seasons of southern China,but negative with the temperature at the same time.Thus this study is necessary for flood control in Shaoguan.