School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ, USA.
Sci Rep. 2021 Mar 18;11(1):6247. doi: 10.1038/s41598-021-85582-y.
Quasi-decadal climate of the Kuroshio Extension (KE) is pivotal to understanding the North Pacific coupled ocean-atmosphere dynamics and their predictability. Recent observational studies suggest that extratropical-tropical coupling between the KE and the central tropical Pacific El Niño Southern Oscillation (CP-ENSO) leads to the observed preferred decadal time-scale of Pacific climate variability. By combining reanalysis data with numerical simulations from a high-resolution climate model and a linear inverse model (LIM), we confirm that KE and CP-ENSO dynamics are linked through extratropical-tropical teleconnections. Specifically, the atmospheric response to the KE excites Meridional Modes that energize the CP-ENSO (extratropicstropics), and in turn, CP-ENSO teleconnections energize the extratropical atmospheric forcing of the KE (tropicsextratropics). However, both observations and the model show that the KE/CP-ENSO coupling is non-stationary and has intensified in recent decades after the mid-1980. Given the short length of the observational and climate model record, it is difficult to attribute this shift to anthropogenic forcing. However, using a large-ensemble of the LIM we show that the intensification in the KE/CP-ENSO coupling after the mid-1980 is significant and linked to changes in the KE atmospheric downstream response, which exhibit a stronger imprint on the subtropical winds that excite the Pacific Meridional modes and CP-ENSO.
黑潮延伸区（KE）的准十年气候对于理解北太平洋海气耦合动力及其可预测性至关重要。最近的观测研究表明，KE 与热带中部太平洋厄尔尼诺南方涛动（CP-ENSO）之间的温带-热带耦合导致了观测到的太平洋气候变化的首选十年时间尺度。通过将再分析数据与高分辨率气候模式和线性逆模式（LIM）的数值模拟相结合，我们证实了 KE 和 CP-ENSO 动力通过温带-热带遥相关联系在一起。具体来说，大气对 KE 的响应激发了纬向模态，从而激发了 CP-ENSO（温带-热带），而 CP-ENSO 遥相关又激发了 KE 的温带大气强迫（热带-温带）。然而，观测和模型都表明，KE/CP-ENSO 耦合是非定常的，并且在 20 世纪 80 年代中期之后加剧。鉴于观测和气候模型记录的长度较短，很难将这种转变归因于人为强迫。然而，使用 LIM 的大集合，我们表明，20 世纪 80 年代中期之后 KE/CP-ENSO 耦合的加剧是显著的，并且与 KE 大气下游响应的变化有关，这种变化对激发太平洋纬向模态和 CP-ENSO 的亚热带风有更强的影响。
