1961~2018年华南全年和四季暴雨的时空特征分析北大核心CSCD

利用中国2400余个国家级气象台站观测数据插值得到的1961~2018年逐日网格降水资料,综合运用回归分析和Morlet小波变换等方法,分析了华南多年暴雨和区域性暴雨的时空变化特征,揭示了华南暴雨的变化规律。结果表明:1961~2018年,华南全年暴雨日数和暴雨雨量大值区域分布在广东、广西、福建沿海一带及海南省和广西北部,夏季暴雨日数和暴雨雨量最大,其次是春季。在广西北部至广西、湖南、广东三省交界处、广东南部、福建和海南省,全年暴雨日数、雨量和强度的增加趋势最显著,夏季的区域平均值增长速率最大,其次是秋季。华南区域性暴雨日数和过程数呈单峰型分布,一年中均可出现,最大值出现在6月。区域性暴雨日数和过程数多年平均值为28 d a^(-1)和16.5 a^(-1),上升速率分别为0.15 d a^(-1)和0.097 a^(-1),四季中夏季的上升速率最快,最慢的是秋季。平均单次过程持续日数和最大单次过程持续日数在冬季均以0.015 d a^(-1)的速率显著上升,在春季却呈现下降的趋势。华南暴雨和区域性暴雨各要素在全年和四季的波动变化中不同程度地表现出准3 a、准14 a和准18 a的周期变化,2000年后,全年暴雨和区域性暴雨各要素准18 a的长周期和准3 a的短周期振荡非常显著。     

Comparative analysis of the cold surge characteristics over China before and after 2000北大核心CSCD

Based on the daily minimum temperature data in China from 1961 to 2018, using n-order polynomial fitting, sliding t-test, empirical Orthogonal Function analysis, Morlet wavelet transform and other methods, this paper reveals the temporal and spatial distribution characteristics of the number of cold surge (CS) day, CS frequency and CS intensity by time and region. The results are as follows. On a national level, the number of CS day, CS frequency, and CS intensity decreased from 1962 to 2000. Specifically, the trend of every element of CS has changed from a previous decrease trend to an increase trend, and the inflection point was around 2000. The CS activity occurred more frequently, became more strengthen, and last for longer time after 2000. There are obvious spatial differences in the number of CS days, CS frequency, CS intensity and their changing trends in China. The number of CS days and CS frequency reach the maximum value in northeast China and northern Inner Mongolia. Meanwhile, the CS intensity value is low in the southeast China and high in the northwest China, with the exception of southern Xinjiang. The changes in the number of CS day and the CS frequency are mainly manifested as the “Northeast, Southwest Reverse Pattern”, the CS intensity is mainly manifested as the “Uniform Change Pattern”. The number of CS day, CS frequency, and CS intensity did not change significantly after, but a significant transition point was detected in 1980. On a regional scale, from 1962 to 2018, the number of CS day, frequency and intensity of cold surge in all regions showed a decreasing trend, while they increased after 2000. In the northern and northeastern of China, mean of three elements of cold surge increased after 2000. The transition year was different in different regions. The transition year of three elements of cold surge in Northeast China were the earliest. Mean value of the number of CS day, CS frequency, and CS intensity have an oscillation period of 3~5 years in total China and all regions. In addition, the periodic oscillations of the number of CS day and CS frequency in all regions are basically the consistent. © 2022 Science Press (China).