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<p>Western boundary currents exert a substantial influence on midlatitude climate variability. While the interannual-to-decadal synchronization of sea surface temperatures (SSTs) between the Gulf Stream (GS) and Kuroshio Extension (KE) is well-documented, termed Boundary Current Synchronization (BCS), its seasonal characteristics and governing mechanisms remain unclear. Using observational datasets, we demonstrate that the BCS exhibits pronounced seasonality, with a robust synchronization in boreal summer (<i>r</i> = 0.57) but weak coupling in winter. This seasonal enhancement of BCS is largely attributed to paired high-pressure anomalies (PHPA) that develop specifically during summer spanning the North Pacific and North Atlantic. The PHPA reduce cloud cover and increase net shortwave radiation, promoting simultaneous SST warming in the KE and GS regions. At the hemispheric scale, the summertime circumglobal teleconnection (CGT) serves as the principal dynamical organizer, its wave-train anchoring high-pressure centers near the GS and KE and triggering the PHPA, thereby linking the two regions’ SST variability through coupled atmosphere-ocean interactions. A substantial fraction of CMIP6 historical (17 out of 28) simulations reproduce the observed coupling, while piControl experiments (20 models) further demonstrate its robustness. MPI-ESM1-2-LR serves as a representative example that captures the key atmospheric circulation features and thermodynamically mediated processes. Further analysis reveals that summertime BCS also exhibits pronounced multidecadal variability, with a marked strengthening after the 1970s that coincides with enhanced atmospheric linkages between North Pacific and North Atlantic geopotential height anomalies. These findings provide insights into trans-basin SST linkages in GS and KE regions and underscore the critical role of hemispheric teleconnections in modulating BCS.</p>

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Seasonal dynamics of Gulf Stream–Kuroshio SST coupling: the role of hemispheric atmospheric teleconnections

  • 期刊论文

  • 发表日期：

    2026年4月4日

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  • Menghao Dong,
  • Cheng Sun,
  • Linfeng Shi,
  • Wei Lou,
  • Zichen Song,
  • Yihua He,
  • Yibing Tong

摘要

Western boundary currents exert a substantial influence on midlatitude climate variability. While the interannual-to-decadal synchronization of sea surface temperatures (SSTs) between the Gulf Stream (GS) and Kuroshio Extension (KE) is well-documented, termed Boundary Current Synchronization (BCS), its seasonal characteristics and governing mechanisms remain unclear. Using observational datasets, we demonstrate that the BCS exhibits pronounced seasonality, with a robust synchronization in boreal summer (r = 0.57) but weak coupling in winter. This seasonal enhancement of BCS is largely attributed to paired high-pressure anomalies (PHPA) that develop specifically during summer spanning the North Pacific and North Atlantic. The PHPA reduce cloud cover and increase net shortwave radiation, promoting simultaneous SST warming in the KE and GS regions. At the hemispheric scale, the summertime circumglobal teleconnection (CGT) serves as the principal dynamical organizer, its wave-train anchoring high-pressure centers near the GS and KE and triggering the PHPA, thereby linking the two regions’ SST variability through coupled atmosphere-ocean interactions. A substantial fraction of CMIP6 historical (17 out of 28) simulations reproduce the observed coupling, while piControl experiments (20 models) further demonstrate its robustness. MPI-ESM1-2-LR serves as a representative example that captures the key atmospheric circulation features and thermodynamically mediated processes. Further analysis reveals that summertime BCS also exhibits pronounced multidecadal variability, with a marked strengthening after the 1970s that coincides with enhanced atmospheric linkages between North Pacific and North Atlantic geopotential height anomalies. These findings provide insights into trans-basin SST linkages in GS and KE regions and underscore the critical role of hemispheric teleconnections in modulating BCS.