Response of Winter Moisture Circulation to the India-Burma Trough and Its Modulation by the South Asian Waveguide
Response of Winter Moisture Circulation to the India-Burma Trough and Its Modulation by the South Asian Waveguide
复制标题
冬季水汽环流对印缅海槽的响应及南亚波导的调制
DOI：
10.1175/jcli-d-16-0111.1
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发表时间：
2017-02-01
影响因子：
4.9
通讯作者：
Zhou, Wen
中科院分区：
文献类型：
--
作者：
Li, Xiuzhen;Chen, Yongqin David;Zhou, Wen
为了寻找中国南部冬季降水的潜在前兆，分析了水汽环流对印缅大槽逐日演变的响应和沿南亚波导区扰动的调制。使用了1979-2012年ERA中期逐日观测降水和再分析资料。结果表明，对IBT作出响应的水汽环流是沿南亚波导纬向波列的一部分，但它比其他波瓣持续时间更长，向东迁移得更远。气旋性水汽输送加强了中国南部的水汽供应，并在IBT高峰期后突然东移，增强的降水由中国西南向东南转移。这种响应是天气成分、季节内成分和年际成分共同作用的结果，这些成分表现出相似的波列结构，但仍有微小的差异。天气分量显示波长较短，路径偏南，相速和群速度较快，从北大西洋到孟加拉湾(BOB)的信号在6天内发出，这意味着北大西洋上的一个扰动是中国南部冬季降水的潜在前兆。天气水汽辐合比上游除东南亚以外的其他尺度的水汽辐合更强烈，各分量具有可比性。这可能是由于短波长在天气尺度上受到来自Bob的水汽来源的限制，而来自Bob-西北太平洋(WNP)的水汽来源在其他尺度上由于波长较长而广泛存在。
The response of moisture circulation to the daily evolution of the India-Burma Trough (IBT) and the modulation of disturbances along the South Asian waveguide are analyzed to seek a potential precursor of winter precipitation over south China. Daily observational precipitation and reanalysis data from ERA-Interim during 1979-2012 are employed. It is found that moisture circulation in response to the IBT is part of the zonally oriented wave trains along the South Asian waveguide, but it persists longer and migrates farther eastward than other lobes. Cyclonic moisture transport enhances the moisture supply to south China as a strong IBT develops, and shifts eastward abruptly after the peak of IBT with enhanced precipitation shifting from southwest to southeast China. This response is a joint effect of synoptic, intraseasonal, and interannual components that show similar wave train structures, whereas slight differences still occur. The synoptic component shows a shorter wavelength, more southerly path, faster phase speed, and group velocity, with the signal from the North Atlantic to the Bay of Bengal (BoB) in 6 days, implying that a disturbance over the North Atlantic is a potential precursor of winter precipitation over south China. The synoptic moisture convergence is more intensive than that at other scales upstream except over Southeast Asia, where all components are comparable. This might result from the constrained moisture source from BoB at the synoptic scale because of a short wavelength, while widespread sources from BoB-western North Pacific (WNP) at other scales as wavelengths are longer.