Possible influence of Arctic oscillation on precipitation along the East Asian rain belt during boreal spring
Possible influence of Arctic oscillation on precipitation along the East Asian rain belt during boreal spring
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DOI：
10.1007/s00704-016-1900-0
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发表时间：
2017-10
影响因子：
3.4
通讯作者：
Jingxuan Qu;D. Gong;Rui Mao;Jing Yang;Sang Li
中科院分区：
文献类型：
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作者：
Jingxuan Qu;D. Gong;Rui Mao;Jing Yang;Sang Li
在这项研究中，春季北极涛动（AO）对降水的可能影响沿着东亚雨带已研究了1979年至2014年期间。为了捕捉大气环流和降水的大尺度变率的特征，进行奇异值分解（SVD）分析。降水区域为21.25 ~ 33.75° N，111.25 ~ 133.25° E，1000 hPa高度场为20° N以北。在分析之前，对厄尔尼诺-南方涛动（ENSO）信号进行线性拟合，并从相关变量中减去。第一对模式解释了总平方协方差的51.1%。气压模态的空间特征与正AO型的空间特征基本一致，降水模态沿雨带总体上呈现沿着偏少的异常。AO指数与气压模态的时间系数高度相关，相关系数为0.91，与降水模态的时间系数相关系数为-0.44，两者均达到99%的显著水平。与负位相AO模态相关的区域大气环流异常表现出一致的变化，包括东亚对流层低层偏南风和水汽通量辐合的异常，东亚西风急流的增强，以及20 ~ 30° N上升气流的增强。AO与东亚环流和降水之间存在两种可能的联系机制，从北非到中东和东亚的西风急流的沿着波列和北太平洋上的反气旋和气旋的偶极子。
In this study, the possible influence of the springtime Arctic oscillation (AO) on precipitation along the East Asian rain belt has been studied for the period of 1979 to 2014. To capture the features of the large-scale variability of the atmospheric circulation and precipitation, singular value decomposition (SVD) analysis was performed. The domain for precipitation is from 21.25 to 33.75° N and 111.25 to 133.25° E, and the 1000 hPa heights are from 20° N northward. Prior to analysis, the El Niño-Southern Oscillation (ENSO) signals were linearly fitted and subtracted from the variables of interest. The first paired modes explain 51.1 % of the total squared covariance. The spatial feature of the pressure mode is almost identical to that of the positive AO pattern, while the precipitation mode displays an overall less-than-normal anomaly along the rain belt. The AO indices are highly correlated with the time coefficients of the pressure mode at a value of 0.91, and for the time coefficients of the precipitation mode, the correlation is −0.44, both of which are significant at the 99 % level. The regional atmospheric circulation anomalies in association with the negative phase AO mode display consistent changes, including the anomalous southerly winds and vapor flux convergence in the lower troposphere over East Asia, the stronger East Asian westerly jet stream, and the enhanced ascending air motion between 20 and 30° N. There are two possible mechanisms linking the AO and East Asian circulation and precipitation, i.e., the wave-trains along the westerly jet stream from North Africa to the Middle East and East Asia and the dipole of an anti-cyclone and a cyclone over the North Pacific.