Influence of the South American Low‐Level Jet on the Austral Summer Precipitation Trend in Southeastern South America
Influence of the South American Low‐Level Jet on the Austral Summer Precipitation Trend in Southeastern South America
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DOI：
10.1029/2021gl096409
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发表时间：
2022-04
影响因子：
5.2
通讯作者：
A. Varuolo-Clarke;A. P. Williams;J. Smerdon;M. Ting;D. Bishop
中科院分区：
文献类型：
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作者：
A. Varuolo-Clarke;A. P. Williams;J. Smerdon;M. Ting;D. Bishop
从1902年到2020年，南美洲东南部（SESA）的夏季降水量增加了27%，这是全球观测到的最大百年降水趋势之一。我们通过分析1951年至2020年两个再分析数据集中进入SESA的低层水汽通量来评估南美低空急流对SESA降水趋势的影响。通过急流增加的水汽通量占观测到的SESA降水趋势的20%-45%。虽然再分析的结果各不相同，但两者都指出湿度增加是水分通量增加和SESA降水的基本驱动因素。喷流内湿度的增加与人为强迫导致的海面温度升高是一致的，尽管其他自然气候变化也可能发挥了作用。急流的速度也增加了，进一步增加了降水，但与人为强迫没有明确的联系。我们的研究结果表明，SESA的降水趋势部分归因于射流增强所产生的自然变率和人为强迫。
Austral summer precipitation increased by 27% from 1902 to 2020 over southeastern South America (SESA), one of the largest centennial precipitation trends observed globally. We assess the influence of the South American low‐level jet on the SESA precipitation trend by analyzing low‐level moisture fluxes into SESA in two reanalysis datasets from 1951 to 2020. Increased moisture flux through the jet accounts for 20%–45% of the observed SESA precipitation trend. While results vary among reanalyzes, both point to increased humidity as a fundamental driver of increased moisture flux and SESA precipitation. Increased humidity within the jet is consistent with warming sea surface temperatures driven by anthropogenic forcing, although additional natural climate variations also may have played a role. The jet's velocity also increased, further enhancing precipitation, but without a clear connection to anthropogenic forcing. Our findings indicate the SESA precipitation trend is partly attributable to jet intensification arising from both natural variability and anthropogenic forcing.