Despite extratropical forcing being recognized as an important factor that can modulate El Niño-Southern oscillation (ENSO) properties on the interannual time scale, little is known about whether and how Arctic forcing changes the tropical sea surface temperature (SST). This current study reveals a significant link between the net surface sensible heat flux (SHF) in the Arctic and the SST anomalies in the tropical eastern Pacific (TEP). Specifically, anomalous upward SHF into the Arctic atmosphere in February leads to a warmer TEP in the subsequent spring and summer. A northeast-southwest-tilted North Pacific Oscillation-like atmospheric pattern associated with the upward Arctic SHF anomaly induces SST cooling in the subtropical North Pacific via positive Wind-Evaporation-SST feedback, which further promotes TEP SST warming via meridional heat advection, thermocline feedback, and nonlinear processes. The spring-to-summer TEP SST anomalies driven by the preceding anomalous Arctic SHF can potentially modulate the seasonal evolution of ENSO. Our findings imply that we should take into account the Arctic-tropics linkages when comprehensively understanding the ENSO variability and improving ENSO projection skills.

中文翻译：

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冬季北极强迫对热带东太平洋随后海面温度异常的潜在影响

尽管温带强迫被认为是可以在年际时间尺度上调节厄尔尼诺-南方涛动（ENSO）特性的重要因素，但人们对北极强迫是否以及如何改变热带海面温度（SST）知之甚少。目前的研究揭示了北极净表面感热通量（SHF）与热带东太平洋海温异常（TEP）之间的显着联系。具体来说，二月份异常向上的超高频进入北极大气导致随后春季和夏季的 TEP 变暖。东北-西南倾斜的北太平洋涛动类大气模式与向上的北极SHF异常相关，通过风-蒸发-海表温度正反馈引起副热带北太平洋海表温度变冷，这进一步通过经向热平流、温跃层反馈促进TEP海表温度变暖和非线性过程。由先前的异常北极 SHF 驱动的春夏季 TEP 海温异常可能会调节 ENSO 的季节演变。我们的研究结果表明，在全面了解 ENSO 变化和提高 ENSO 预测技能时，我们应该考虑北极与热带地区的联系。