Modulations of rising motion and moisture on summer precipitation over the middle and lower reaches of the Yangtze river
Modulations of rising motion and moisture on summer precipitation over the middle and lower reaches of the Yangtze river
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上升运动和水汽对长江中下游夏季降水的调节作用
DOI：
10.1007/s00382-018-4247-7
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发表时间：
2018-12-01
期刊：
影响因子：
4.6
通讯作者：
Zhou, Wen
中科院分区：
文献类型：
--
作者：
Leung, Marco Y. T.;Qiu, Shuang;Zhou, Wen
利用1960 - 2012年长江中下游夏季降水资料，分析了垂直运动和水汽对长江中下游夏季降水变化的贡献。偏回归分析表明，局地垂直运动和水汽与夏季降水的变化有显著的相关关系。同时考虑垂直运动和水汽的影响，较好地再现了降水的时间变化。此外，我们将夏季降水的变化分为线性趋势和变化（去趋势值）。应注意的是，线性趋势仅由垂直运动的趋势贡献。随后，我们用连续性方程研究了垂直运动的趋势。结果表明，垂直运动的趋势是由对流层低层静稳定度的下降趋势引起的。另一方面，变化是由垂直运动和水分控制。垂直运动的变化是由对流层中层的异常辐合和对流层低层的静稳定度所强迫的。水汽输送的异常辐合是造成水汽变化的主要原因。这些变化与西北太平洋副热带高压的西南延伸有关。
The contributions of vertical motion and moisture to the variation in summer precipitation over the middle and lower reaches of the Yangtze River over the period from 1960 to 2012 summers are documented in this study. Based on partial regression analysis, it is noted that both local vertical motion and moisture are significantly related to changes in summer precipitation. The temporal variation of the precipitation is well reproduced by considering both vertical motion and moisture. Furthermore, we separated the changes in summer precipitation into a linear trend and variation (detrended value). It is noted that the linear trend is contributed solely by the trend in vertical motion. Subsequently, we examined the trend in vertical motion with a continuity equation. The result signifies that the trend in vertical motion is caused by a decreasing trend in static stability in the lower troposphere. On the other hand, the variation is controlled by both vertical motion and moisture. The change in vertical motion is forced by the anomalous convergence in the midtroposphere and static stability in the lower troposphere. The change in moisture is contributed by the anomalous convergence of moisture transport. These changes are related to the southwestward extension of the western North Pacific subtropical high.