Interdecadal variability of summer precipitation in the Three River Source Region: Influences of SST and zonal shifts of the East Asian subtropical westerly jet

IF 2.3 4区 地球科学 Q3 METEOROLOGY & ATMOSPHERIC SCIENCES
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引用次数: 0

Abstract

Summer precipitation in the Three Rivers Source Region (TRSR) of China is vital for the headwaters of the Yellow, Yangtze, and Lancang rivers and exhibits significant interdecadal variability. This study investigates the influence of the East Asian westerly jet (EAWJ) on TRSR rainfall. A strong correlation is found between TRSR summer precipitation and the Jet Zonal Position Index (JZPI) of the EAWJ from 1961 to 2019 (R = 0.619, p < 0.01). During periods when a positive JZPI indicates a westward shift in the EAWJ, enhanced water vapor anomalies, warmer air, and low-level convergence anomalies contribute to increased TRSR summer precipitation. Using empirical orthogonal function and regression analyses, this research identifies the influence of large-scale circulation anomalies associated with the Atlantic–Eurasian teleconnection (AEA) from the North Atlantic (NA). The interdecadal variability between the NA and central tropical Pacific (CTP) significantly affects TRSR precipitation. This influence is mediated through the AEA via a Rossby wave train extending eastward along the EAWJ, and another south of 45°N. Moreover, the NA–CTP Opposite Phase Index (OPI), which quantifies the difference between the summer mean sea surface temperatures of the NA and the CTP, is identified as a critical factor in modulating the strength of this teleconnection and influencing the zonal position of the EAWJ.

摘要

本研究探讨了年代际东亚西风急流的纬向移动对黄河, 长江和澜沧江源头—三江源区夏季降水的影响. 研究发现, 在1961–2019年间, 三江源区夏季降水量与急流纬向位置指数 (JZPI) 在年代际尺度上存在强正相关 (R=0.619, p<0.01) . 当JZPI呈正值, 也就是东亚西风急流向西移动时, 增强的水汽, 温暖的气流和低层辐合异常有助于三江源区夏季降水增加. 北大西洋与中太平洋之间的年代际变化对三江源区的降水有着显著的影响, 主要以北大西洋–欧亚遥相关 (AEA) 方式, 通过沿东亚西风急流向东延伸的罗斯贝波列, 以及45°N以南的另一波列来影响三江源区的降水. 进一步分析发现, 北大西洋与中太平洋反向相位指数 (OPI) 作为一个关键因素, 可量化北大西洋与中太平洋之间夏季平均海表温度的差异, 调控该遥相关的强度并影响急流的纬向位置.

Abstract Image

三江源地区夏季降水的年代际变化:海温和东亚副热带西风气流带状移动的影响
中国三江源地区(TRSR)的夏季降水对黄河、长江和澜沧江的源头至关重要,并表现出显著的年代际变化。本研究探讨了东亚西风气流(EAWJ)对三江源地区降雨的影响。研究发现,1961-2019 年 TRSR 夏季降水量与东亚西风气流的喷气带位置指数(JZPI)之间存在很强的相关性(R = 0.619,p <0.01)。在 JZPI 为正值表明 EAWJ 西移的时期,水汽异常、暖空气和低层辐合异常增强,导致 TRSR 夏季降水量增加。这项研究利用经验正交函数和回归分析,确定了与来自北大西洋的大西洋-欧亚大陆遥联系(AEA)相关的大尺度环流异常的影响。北大西洋与热带太平洋中部之间的年代际变率对 TRSR 降水量有显著影响。这种影响是通过沿 EAWJ 向东延伸的罗斯比波列和北纬 45 度以南的另一个罗斯比波列通过 AEA 产生的。此外,NA-CTP 相反相位指数(OPI)量化了 NA 和 CTP 夏季平均海面温度之间的差异,被认为是调节这一远缘联系强度和影响 EAWJ 区域位置的关键因素。摘要本研究探讨了年代际东亚西风急流的纬向移动对黄河、长江和澜沧江源头-三江源区夏季降水的影响。研究发现, 在1961-2019年间, 三江源区夏季降水量与急流纬向位置指数 (JZPI) 在年代际尺度上存在强正相关 (R=0.619, p<0.01) .当 jzpi 呈正值, 也就是东亚西风急流向西移动时, 增强的水汽, 温暖的气流和低层辐合异常有助于三江源区夏季降水增加.北大西洋与中太平洋之间的年代际变化对三江源区的降水有着显著的影响, 主要以北大西洋-欧亚遥相关 (aea) 方式, 通过沿东亚西风急流向东延伸的罗斯贝波列, 以及 45°N以南的另一波列来影响三江源区的降水。进一步分析发现, 北大西洋与中太平洋反向相位指数 (opi) 作为一个关键因素, 可量化北大西洋与中太平洋之间夏季平均海表温度的差异, 调控该遥相关的强度并影响急流的纬向位置.
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来源期刊
Atmospheric and Oceanic Science Letters
Atmospheric and Oceanic Science Letters METEOROLOGY & ATMOSPHERIC SCIENCES-
CiteScore
4.20
自引率
8.70%
发文量
925
审稿时长
12 weeks
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