靳莉君,赵平. 2012. 夏季南海季风对长江中下游季风降水影响的观测分析和数值模拟[J]. 气象学报, 70(4):670-680, doi:10.11676/qxxb2012.054
夏季南海季风对长江中下游季风降水影响的观测分析和数值模拟
Observationally analyzing and numerically simulating the impacts of the South China Sea summer monsoon on summer monsoon rainfall in the middle-lower reaches of the Yangtze River
投稿时间:2011-02-01  修订日期:2011-05-06
DOI:10.11676/qxxb2012.054
中文关键词:  南海季风,长江中下游降水,观测分析,数值模拟,年际变率
英文关键词:The South China Sea monsoon, Precipitation in the middle lower reaches of the Yangtze River, Observational analysis, Numerical simulation, Interannual variability
基金项目:国家自然科学基金创新群体基金(40921003)、国家国际科技合作专项(2011DFG23450)
作者单位
靳莉君 灾害性天气国家重点实验室, 中国气象科学研究院, 北京, 100081 
赵平 灾害性天气国家重点实验室, 中国气象科学研究院, 北京, 100081
国家气象信息中心, 北京, 100081 
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中文摘要:
      利用ERA-40、NCEP/NCAR再分析资料、NOAA的CMAP降水资料以及MM5v3中尺度模式,通过定义一个东亚热带季风强度指数,从观测资料和数值模拟角度研究夏季(6—7月)南海季风异常变化对长江中下游季风和降水的影响。从资料分析结果可以看出,在年际尺度变率上,6—7月南海热带季风和降水与长江中下游的西南风和降水存在着反位相变化关系,当热带季风和降水偏强(弱)时,长江中下游西南季风偏弱(强)、降水偏少(多);数值模拟结果进一步表明,当改变南海季风强度时,长江中下游季风和降水都有显著的变化,其异常特征与观测结果基本一致,这证明了热带季风对长江中下游季风降水的影响,并且,这种影响可以得到物理过程的支持;此外,在年际变率上,当夏季热带季风偏强时,热带异常西风和降水正异常主要维持在热带地区,未向北移到长江中下游地区,因而未加强对中国南方地区的水汽输送,亦未引起中国南方西南气流和降水加强;相反,偏强的热带季风通过调整大气内部过程引起西太平洋副热带高压脊减弱且位置偏南,使长江中下游的西南季风和降水强度减弱。
英文摘要:
      The ERA-40 and NCEP/NCAR reanalysis datasets, the NOAA’s Climate Prediction Center’s merged analysis of precipitation (CMAP), and the fifth-generation PSU/NCAR Meso scale Model version 3 (MM5v3) were used to define a monsoon intensity index over the East Asian tropical region and to analyze the impacts of the summer (June-July) South China Sea (SCS) monsoon anomaly on the monsoon precipitation over the middle lower reaches of the Yangtze River (YR) from observations and numerical simulations. The results from the reanalysis data show that the interannual variations of the tropical monsoon and precipitation over SCS are negatively correlated with the southwestern winds and precipitation over the YR middle-lower reaches during June and July. Corresponding to stronger (weaker) tropical monsoon and precipitation, the southwesterly is weaker (stronger) over the YR middle lower reaches, with the local less (more) precipitation. The simulation results further exhibit that when the SCS monsoon (SCSM) intensity changes, there are significant variations in the monsoon and precipitation over the YR middle-lower reaches. The simulated anomalies are generally consistent with the observational results, which support the argument concerning the impact of SCSM on the monsoon precipitation over the YR middle-lower reaches. This impact can be elucidated by physical processes. Moreover, when the summer SCSM is stronger, tropical anomalous westerly winds and positive precipitation anomalies generally maintain in the tropics and do not move northwards into the YR middle-lower reaches, not strengthening the transportation of water vapor toward southern China and not causing the strengthening of the southwest flow and precipitation over southern China. On the contrary, the stronger SCSM may result in the weakening and southward shift of the western Pacific subtropical ridge through adjusting the atmospheric intrinsic processes, leading to the weakening of the monsoon and precipitation over the YR middle-lower reaches.
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