2026-02-13 北海道大学,海洋研究開発機構
黒潮続流域の海面水温変動から貿易風への影響は、亜熱帯域から熱帯域にかけての大気と海洋の相互作用を促す
＜関連情報＞
- https://www.hokudai.ac.jp/news/2026/02/post-2181.html
- https://www.hokudai.ac.jp/news/pdf/260213_pr.pdf
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025GL118296
大気内部変動の影響下における北西太平洋の中緯度海面水温上昇に対する亜熱帯の大気応答 Subtropical Atmospheric Response to Extratropical SST Warming in the Western North Pacific Under Atmospheric Internal Variability Itsuki Miura, Youichi Tanimoto Geophysical Research Letters Published: 12 February 2026 DOI:https://doi.org/10.1029/2025GL118296
Abstract
Sea surface temperature (SST) anomalies in the Kuroshio Extension (KE) region have been increasingly recognized as playing a key role in shaping the extratropical air–sea interactions. However, the extent to which such extratropical SST forcing can influence large-scale atmospheric circulation and surrounding SST remains uncertain, particularly given strong atmospheric internal variability. Here, we investigate the atmospheric response to idealized positive SST anomalies in the KE region using large-ensemble atmospheric general circulation model experiments. The imposed forcing generates a robust sea-level pressure anomaly over and downstream of the KE, leading to surface westerly wind anomalies extending into the subtropical North Pacific. Despite substantial atmospheric internal variability over the Aleutian Low region, these subtropical wind anomalies consistently emerge across the ensemble. Our results suggest that SST forcing in the KE region can modulate air–sea interactions not only locally but also across a broader region extending equatorward.
Plain Language Summary
In the North Pacific, the Kuroshio Extension (KE) is one of the major western boundary currents, located off the east coast of Japan. Sea surface temperature (SST) anomalies in this region play a crucial role in extratropical air–sea interactions because the KE releases large amounts of heat and moisture into the atmosphere, particularly during boreal winter. However, due to strong atmospheric internal variability in the extratropics, it has been difficult to clearly identify how SST anomalies in the KE affect large-scale atmospheric patterns. In this study, we investigated the atmospheric response to idealized positive SST anomalies in the KE using a set of 100 atmospheric general circulation model experiments. By analyzing the atmospheric responses with careful consideration of internal variability, we identified a robust pattern of westerly wind anomalies extending equatorward from the KE region. These westerly winds weaken the background trade winds and reduce ocean surface heat loss, potentially contributing to warm SST anomalies in the subtropics. Our study highlights that the atmospheric responses to SST forcing in the KE region are not confined locally but also influence the subtropical North Pacific.
Key Points
- Positive sea surface temperature (SST) anomalies in the Kuroshio Extension region induce robust low-pressure and wind responses in the lower atmosphere
- A key robust feature is the emergence of westerly wind anomalies in the subtropical North Pacific, independent of internal variability
- These wind anomalies likely contribute to subtropical SST warming, suggesting broader air–sea coupling
