刘蕾,孙颖,张蓬勃. 2014. 大尺度环流的年代际变化对初夏华南持续性暴雨的影响[J]. 气象学报, 72(4):690-702, doi:10.11676/qxxb2014.031
大尺度环流的年代际变化对初夏华南持续性暴雨的影响
The influence of decadal change of the large-scale circulation on persistent torrential precipitation over South China in early summer
投稿时间:2013-08-30  修订日期:2014-01-15
DOI:10.11676/qxxb2014.031
中文关键词:  华南持续性暴雨  年代际变化  大尺度环流差异
英文关键词:Persistent torrential precipitation (PTP) over South China  Decadal change  Large-scale circulation difference
基金项目:国家重点基础研究发展计划973项目(2012CB417205)、公益性气象行业专项(201406042)。
作者单位
刘蕾 芜湖市气象局, 芜湖, 241000 
孙颖 国家气候中心, 北京, 100081 
张蓬勃 南京市气象局, 南京, 210009 
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中文摘要:
      利用1961-2010年中国逐日降水数据和NCEP/NCAR逐日再分析资料集,研究了大尺度环流的年代际变化对不同频发年代华南持续性暴雨的影响。结果表明,虽然过去50年里华南持续性暴雨的发生存在两个频发时段(20世纪60年代中期到70年代中期、20世纪90年代初到2010年),其典型环流配置都表现为中高纬度冷空气和低纬度充沛水汽的配合,但不同频发时段的大尺度环流配置明显不同,这种配置使得两个频发时段的暴雨发生特点有所不同,最近20年的暴雨发生次数更多,强度更强,持续时间更长。在频发的1964-1976年,高纬度的冷空气主要来自西西伯利亚上空深厚的低槽前部,而此时南亚高压偏弱,西太平洋副热带高压偏弱、偏东,低纬度的水汽主要来自孟加拉湾印缅低压槽前,可降水量偏小,但垂直速度较大,水汽辐合较旺盛,华南上空大气环流较不稳定;在频发的1991-2010年,鄂霍次克海上空附近的高压脊活跃,高纬度冷空气主要来自高压后部,低纬度西太平洋副热带高压偏强,位置偏西,其西北侧的水汽源源不断输送到华南上空,故可降水量增多,伴随着强大的南亚高压提供的良好的高层辐散条件,华南上空垂直速度增大,水汽辐合明显,强有利的环流配置导致1991-2010年华南持续性暴雨强度更大、范围更广。因此,大气环流的年代际转型使得华南持续性暴雨发生了巨大改变,故在未来做预测时应充分考虑不同年代际环流背景场对华南持续性暴雨的重要影响。
英文摘要:
      Based on the China daily rainfall data and the NCEP/NCAR reanalysis data in 1961-2010, the influence of decadal change of the large-scale circulation on persistent torrential precipitation (PTP) in the different frequent periods over South China has been explored. The results show that during the two periods with frequent persistent torrential precipitation events (from the mid-1960s to mid-1970s and from the 1990s to around 2010) in the past 50 years although the occurrence of persistent torrential precipitation is generally accompanied by the cold air from the middle-high latitudes and sufficient vapor supply from the low latitudes, the large-scale circulation in the different periods show obvious difference. Therefore, the characteristics of persistent torrential precipitation in the two periods are different. In the recent twenty years, persistent torrential precipitation occurs more frequently and its intensity is stronger. During the persistent torrential precipitation active period in 1964-1976, the cold air originated from the front part of a wide low trough in West Siberia while water vapor came from the India-Burma trough in the Bay of Bengal. Meanwhile, the western North Pacific high was weak and shifts eastward, and the South Asian high was weak as well. Precipitable water was not more than normal, but the vertical velocity and vapor convergence was strong, resulting in a quite stable background over South China. Whereas during the persistent torrential precipitation active period from the 1990s to 2010s, cold air was from the back of the active high pressure ride over Okhotsk Sea, and the western North Pacific high is strong and shifts westward, which enhanced water vapor transport into South China from its northwest side. Meanwhile, the strong South Asian high provided upper-level divergence over South China, which enhanced vertical ascending motion, vapor convergence and sufficient precipitable water, and persistent torrential precipitation intensity is stronger and its influence areas are wider during this period. These features suggest that the decadal adjustment of the large-scale circulation can lead to decadal change of persistent torrential precipitation, and the influence of decadal variation of climate background on persistent torrential precipitation should be considered in making the relevant prediction.
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