2010年华南前汛期持续性降水异常与准双周振荡  

PERSISTENT PRECIPITATION ANOMALIES AND QUASI-BIWEEKLY OSCILLATION DURING THE ANNUALLY FIRST RAINY SEASON OVER SOUTH CHINA IN 2010

作　　者：苗芮[1] 温敏[1,2] 张人禾[1] 

机构地区：[1]中国气象科学研究院,北京100081 [2]南京信息工程大学气象灾害预报预警与评估协同创新中心,江苏南京210044

出　　处：《热带气象学报》2017年第2期155-166,共12页Journal of Tropical Meteorology

基　　金：国家重点基础研究发展项目规划"973"(2012CB417205);国家自然科学基金项目(41221064);中国气象科学研究院基本科研经费(2015Z001)共同资助

摘　　要：利用中国台站逐日降水资料以及NCEP-DOE逐日再分析资料,分析了2010年华南汛期降水异常的低频特征及大气环流的影响。结果表明,2010年华南汛期降水异常呈显著的低频振荡特征,其中前汛期以10~20天振荡(准双周振荡)为主,后汛期以20~50天振荡(季节内振荡)为主。重点讨论了准双周尺度上前汛期持续性降水异常与中高纬和热带地区大气低频振荡的关系。中高纬地区的低频环流可通过Rossby波能量沿着低频遥相关波列的频散影响华南低频环流的变化。波活动通量分析显示,西西伯利亚作为Rossby波源,其波能量沿着横跨欧亚大陆的低频遥相关波列向我国东部地区频散,引起该地扰动加强,从而引起华南低频环流及垂直运动的变化进而造成华南降水的异常。热带东印度洋的准双周振荡是影响华南前汛期降水的另一低频来源。当赤道东印度洋对流旺盛(抑制),其上空为强上升(下沉)气流,低层辐合(辐散)高层辐散(辐合),而华南上空盛行下沉(上升)运动,不利于(有利于)华南降水。来自中高纬和低纬的低频信号的叠加并配合低频水汽输送共同影响了华南环流异常的低频变化,从而引起华南的低频降水异常,有利于华南持续性降水异常的发生。Based on the in-situ daily precipitation from Chinese Meteorological Administration（CMA） and the National Centers for Environmental Prediction-Department of Energy（NCEP-DOE） daily reanalysis data, the low-frequency characteristics of precipitation anomalies and the impact of atmospheric circulation during the rainy seasons of South China in 2010 are investigated. The results show that the precipitation anomalies during this period have obvious low-frequency characteristics. Specifically, the annually first rainy season is controlled by a 10-20-day oscillation （quasi-biweekly oscillation）, while the annually second rainy season is controlled by a 20 ＂-50-day oscillation （intraseasonal oscillation）. With focus on the quasi-biweekly oscillation, the relationship between the persistent precipitation anomalies and the atmospheric low-frequency oscillation at mid-high latitude and tropical zone during the annually first season is discussed. The low-frequency circulation at the mid-high latitude can influence the low-frequency circulation over South China by the dispersion of Rossby wave along the low-frequency wave train. The analysis of wave activity flux indicates that the wave energy originated from West Siberia disperses toward the eastern China along the low-frequency teleconnection wave train which stretches across the Eurasian continent, leading to the strengthening of the disturbance over eastern China and the precipitation anomalies by changing the low-frequency circulation and vertical movement over South China. The quasi-biweekly oscillation over the tropical eastern Indian Ocean （IO） is another low-frequency origin influencing the annually first season of South China. When the convection over the eastern equatorial IO is strong （inhibited）, there are strong ascending （descending） movements in this region accompanied with convergence （divergence） at lower layer and convergence （divergence） at upper atmosphere. At the same time, descending （ascending） wind prevails ov

关 键 词：华南前汛期 降水异常 准双周振荡 遥相关波列 热带低频对流活动 

分 类 号：P426.6[天文地球—大气科学及气象学]