The relationship between June precipitation over mid-lower reaches of the Yangtze River basin and spring soil moisture over the East Asian monsoon region
The relationship between June precipitation over mid-lower reaches of the Yangtze River basin and spring soil moisture over the East Asian monsoon region
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DOI：
10.1007/s13351-011-0310-6
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发表时间：
2011-07
影响因子：
--
通讯作者：
Yanling Zhan;Zhaohui Lin
中科院分区：
文献类型：
--
作者：
Yanling Zhan;Zhaohui Lin
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。6月平均降水量与前期土壤含水量呈显著正相关。还研究了这种关系的可能响应机制。结果表明，当4、5月MRL-YRB上空土壤较常年偏湿（偏干）时，该地区5月对流层低层气温较常年偏低（偏高），这种温度效应导致海陆温差减小（增大）。海陆温差的减小（增大）一般导致6月东亚夏季风减弱（增强）。850 hPa偏南（北）风异常在长江流域南部出现，而偏北（南）风异常在长江流域北部占主导地位。这些异常导致了风和水汽的辐合（辐散），从而导致了MLR-YRB地区6月降水量的增加（减少）。
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 MRL-YRB. The possible response mechanism for this relationship was also investigated. It is found that when the soil over the MRL-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.