Destructive interference of ENSO on North Pacific SST and North American precipitation associated with Aleutian low variability
Destructive interference of ENSO on North Pacific SST and North American precipitation associated with Aleutian low variability
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DOI：
10.1175/jcli-d-21-0560.1
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发表时间：
2022-02
影响因子：
4.9
通讯作者：
S. Larson;Y. Okumura;K. Bellomo;Melissa L. BREEDENe
中科院分区：
文献类型：
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作者：
S. Larson;Y. Okumura;K. Bellomo;Melissa L. BREEDENe
确定北半球冬季气候变化的起源需要仔细地归因于El Niño -南方涛动（ENSO）的作用。例如，阿留申低变率源于内部大气动力学，主要通过ENSO远程强迫。ENSO如何改变当地海表温度（SST）和北美降水对阿留申低变率的响应尚不清楚，因为梳理ENSO信号是困难的。本研究利用精心设计的耦合模型实验来解决这一问题。在没有ENSO的情况下，一个更深的阿留申低压驱动一个类似太平洋年代际涛动（PDO）的正海温响应。然而，与观测到的PDO型不同，整个副热带北太平洋形成了一个由湍流热通量驱动的温暖海温异常的连贯纬向带。此外，非enso阿留申低变率与局限于北太平洋和北美的大尺度大气环流型态以及横跨美国东南部的干燥降水异常有关。当ENSO在实验中被纳入阿留申低变率的强迫时，ENSO遥相关调节了湍流热通量，并抑制了非ENSO阿留申低变率引起的副热带海温异常。与非ENSO源驱动的阿留申低压不同，ENSO强迫导致了美国东南部的湿降水异常。因此，我们发现ENSO远相关对副热带北太平洋海温和与非ENSO阿留申低变率相关的美国东南部降水信号具有破坏性干扰作用。
Identifying the origins of wintertime climate variations in the Northern Hemisphere requires careful attribution of the role of El Niño - Southern Oscillation (ENSO). For example, Aleutian low variability arises from internal atmospheric dynamics and is remotely forced mainly via ENSO. How ENSO modifies the local sea surface temperature (SST) and North American precipitation responses to Aleutian low variability remains unclear, as teasing out the ENSO signal is difficult. This study utilizes carefully designed coupled model experiments to address this issue. In the absence of ENSO, a deeper Aleutian low drives a positive Pacific Decadal Oscillation (PDO)-like SST response. However, unlike the observed PDO pattern, a coherent zonal band of turbulent heat flux-driven warm SST anomalies develops throughout the subtropical North Pacific. Furthermore, non-ENSO Aleutian low variability is associated with a large-scale atmospheric circulation pattern confined over the North Pacific and North America and dry precipitation anomalies across the southeast United States. When ENSO is included in the forcing of Aleutian low variability in the experiments, the ENSO teleconnection modulates the turbulent heat fluxes and damps the subtropical SST anomalies induced by non-ENSO Aleutian low variability. Inclusion of ENSO forcing results in wet precipitation anomalies across the southeast United States, unlike when the Aleutian low is driven by non-ENSO sources. Hence, we find that the ENSO teleconnection acts to destructively interfere with the subtropical North Pacific SST and southeast United States precipitation signals associated with non-ENSO Aleutian low variability.