Impacts of the North Atlantic subtropical high on interannual variation of summertime heat stress over the conterminous United States
Impacts of the North Atlantic subtropical high on interannual variation of summertime heat stress over the conterminous United States
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DOI：
10.1007/s00382-019-04708-1
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发表时间：
2019-03
期刊：
影响因子：
4.6
通讯作者：
Wenhong Li;Tian Zou;Tian Zou;Laifang Li;Yi Deng;Victor Sun;Qinghong Zhang;J. B. Layton;S. Setoguchi
中科院分区：
文献类型：
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作者：
Wenhong Li;Tian Zou;Tian Zou;Laifang Li;Yi Deng;Victor Sun;Qinghong Zhang;J. B. Layton;S. Setoguchi
热指数（HI）为公众提供了热应激和不适的可靠指标。该指数考虑了温度和湿度的综合影响，这两个因素都受到大尺度环流模式的调节。本文分析了北大西洋副热带高压（NASH）对美国大陆上空HI的影响，结果表明，美国大陆上空HI主要受地面气温的控制，而与40°N以北的美国中西部地区的相对湿度呈负相关。此外，风有助于在美国中西部和东南部的HI的变化。通过调节这些气象参数，NASH西部高压脊的移动显著影响了美国，特别是东南部的HI。当NASH西部高压脊位于其气候平均位置的西北部时，由于云量减少和降水不足，观察到异常高温，导致美国东南部上空出现正HI异常。相反，当西脊位于西南部时，尽管100°W以东的相对湿度增加，但东南部的温度降低，HI距平变为负距平。当NASH远离北美大陆时，特别是在东南（SE）脊年，它对HI的影响较弱。在未来，CMIP5模型预计在整个美国大陆的HI增加，而NASH引起的HI将在西北，东南和东北脊年减弱，但加强时，其脊移动到西南象限。这些结果表明，未来热应激的增加可能是由气候变暖和NASH加剧引起的。
Heat index (HI) provides a proven indicator of heat stress and discomfort for the general public. The index takes the integrated effects of both temperature and humidity into account, and both factors are regulated by large-scale circulation patterns. This study examines theimpacts of the North Atlantic Subtropical High(NASH)on HI over theconterminousUnited States(CONUS).Theanalysis suggests that the HI is primarily controlled by surface air temperature over the CONUS; but is negatively correlated with relative humidity in the western and Central US north of 40°N. In addition, winds contribute to the variation of HI in the Midwest and the southeastern US. By regulating these meteorological parameters, the movement of the NASH western ridge significantly impacts HI over the US, especially the Southeast. When the NASH western ridge is located northwest (NW) of its climatological mean position, abnormally high temperatures are observed due to fewer clouds and a precipitation deficit, leading to positive HI anomalies over the southeastern US. In contrast, when the western ridge is located in the southwest (SW), temperature decreases and HI anomaly becomes negative over the Southeast, even though relative humidity increases east of 100°W. NASH has a weaker impact on the HI when it is far from the North American continent, especially during southeast (SE) ridge years. In the future, CMIP5 models project an increase in HI over the entire CONUS, while NASH-induced HI will be weakened during the NW, SE and NE ridge years but strengthened when its ridge moves to the SW quadrant. These results suggest that future increases in heat stress are likely caused by climatological warming and NASH intensification.