詹艳玲,林朝晖. 2012. 6月长江中下游降水和春季东亚季风区土壤湿度的关系[J]. 气象学报, 70(2):236-243, doi:10.11676/qxxb2012.023
6月长江中下游降水和春季东亚季风区土壤湿度的关系
The relationship between June precipitation over mid-lower reaches of the Yangtze River basin and spring soil moisture over the East Asian monsoon region.
投稿时间:2009-05-25  修订日期:2011-07-20
DOI:10.11676/qxxb2012.023
中文关键词:  春季土壤湿度, 海陆温差, 长江流域夏季降水异常, 东亚夏季风
英文关键词:Spring soil moisture, Land-sea temperature contrast, Summer rainfall anomaly over the Yangtze River basin, East Asian summer monsoon
基金项目:国家重点基础研究发展计划项目(2009CB421406)、财政部与科技部公益性行业专项项目(GYHY200906016)、国家科技支撑项目(2007BAC29B03)和国家自然科学基金委创新研究群体项目(40821092)
作者单位
詹艳玲 中国科学院大气物理研究所国际气候与环境科学中心北京100029 
林朝晖 中国科学院大气物理研究所国际气候与环境科学中心北京100029 
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中文摘要:
      利用美国气候预测中心(CPC)土壤湿度资料、中国台站观测降水资料以及NCEP/NCAR再分析的风场和气温资料,在去除了降水资料中的ENSO信号的影响后,分析了6月长江中下游降水和春季东亚季风区土壤湿度的关系。结果表明,长江中下游6月降水和前期春季土壤湿度存在很显著的正相关关系。进一步分析表明,当中晚春(4—5月)长江中下游地区的土壤湿度偏高(低)时,晚春(5月)长江中下游上空低层气温偏低(高),从而导致东亚季风区的海陆温差减小(增加)。海陆温差的减弱(增强)使得6月东亚夏季风较常年偏弱(强),伴随的风场异常主要体现在长江以南地区为南风(北风)异常所控制,而长江以北则为北风(南风)异常,从而使得长江中下游存在着异常辐合(散),最终导致长江中下游降水量较常年偏多(少)。
英文摘要:
      Using the US Climate Prediction Center (CPC) soil moisture dataset and the observed precipitation over China together with the NCEP/NCAR reanalysis wind and air temperature, the relationship between June precipitation over mid-lower reaches of the Yangtze River basin (MLR-YRB) and spring soil moisture over the East Asian monsoon region was explored, with the signal of the ENSO effect on precipitation removed. A significant positive correlation was found between the mean June precipitation and the preceding soil moisture over the MLR-YRB. The possible response mechanism for this relationship was also investigated. It is found that when the soil over the MLR-YRB is wetter (drier) than normal in April and May, the air temperature in the lower troposphere over this region in May is lower (higher) than normal, and this temperature effect leads to a decrease (increase) in the temperature contrast between the land and the sea. Generally, a decrease (increase) in the land-sea temperature contrast leads to weaker (stronger) East Asian summer monsoon in June. Southerly (northerly) wind anomalies at 850 hPa then show up in the south of the Yangtze River basin while northerly (southerly) wind anomalies dominate in the north. These anomalies lead to the convergence (divergence) of wind and water vapor and hence gives rise to more (less) precipitation in June over the MLR-YRB.
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