2000-2025年北极沿海气旋影响交换流的长期变化
Long-term Variations of Cyclone-Influenced Exchange Flows in the Coastal Arctic in 2000-2025
- Louisiana State University（路易斯安那州立大学）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本研究利用26年重建数据，发现北极泻湖夏季东风变率下降、西风增多，极端事件变化显著，影响生态系统连通性。
中文摘要 AI 辅助
夏季天气尺度过程通过气象潮调节北极陆-海交换，发生在无冰期，此时波弗特高压的盛行东风被偶发的北极气旋打断，使海岸风转为西风。我们利用一项经新的现场观测和FVCOM模拟验证的26年重建数据（2000-2025），分析了阿拉斯加北部一个泻湖的风驱交换流。对ERA5数据的相空间EOF分析将深层气旋异常与89%的极端东向通流（EET）事件（27次中的24次）联系起来。海岸东风出现频率呈持续下降趋势（在>10 m/s风速下下降最多达38.3%），而低至中等强度西风出现频率增加最多达30.9%，但在极端西风风速（>10 m/s）下则下降40.6%。离岸ERA5风出现频率增加，其中极端离岸事件（>10 m/s）增加82.4%。当地ASOS观测显示，大气强迫变率近乎单调下降约88%（东西向风偏移变率从2.98×10^4公里降至0.35×10^4公里）。进出流偏移变率稳步下降70%，从1.40×10^3公里降至<0.40×10^3公里，而正向（向外）流比例变率则从7.4%稳步收缩至低于2.2%。极端西向通流（EWT）事件不常见，但集中在最近时期，六次事件中有五次发生在2022-2024年，一次发生在2013年。这些结果表明，夏季海岸风况仍以东风为主，但表现出逐渐降低的变率，同时风分布向更频繁的低至中等强度西风转变。这种天气强迫状态的演变可能影响北极泻湖生态系统的冲刷和生物地球化学连通性。
英文摘要
Summertime synoptic weather regulates Arctic land-ocean exchange through meteorological tides during the ice-free period, when the predominantly easterly regime of the Beaufort High is punctuated by episodic Arctic cyclones, changing coastal winds to westerlies. We analyze wind-driven exchange flows in a northern Alaska lagoon using a 26-year reconstruction (2000-2025) validated by new in situ observations and FVCOM simulations. Phase-space EOF analysis of ERA5 data links deep cyclonic anomalies to 89% of Extreme Eastward Throughflow (EET) events (24 of 27). Coastal easterly occurrence frequencies show a consistent decrease (up to 38.3% at > 10 m/s) while low-to-moderate westerly occurrence frequencies increase by up to 30.9% but decrease by 40.6% at extreme westerly wind speeds (>10 m/s). Offshore ERA5 wind occurrence frequencies increased, with extreme offshore events (> 10 m/s) increasing by 82.4%. Local ASOS observations reveal a near-monotonic ~88% reduction in atmospheric forcing variability (East-West Wind Excursion variability drops from 2.98X10^4 to 0.35X10^4 km). The In-Out Flow Excursion variability declines steadily by 70% from 1.40X10^3 to <0.40X10^3 km, while the positive (outward) flow ratio variability contracts steadily from 7.4% to below 2.2%. Extreme Westward Throughflow (EWT) events were infrequent, but were concentrated in the most recent period, with five of six events occurring in 2022-2024 and one in 2013. These results indicate that the summertime coastal regime remains predominantly easterly, but exhibits progressively lower variability, while the wind distribution shifts toward more frequent low-to-moderate westerlies. This evolution of weather-forcing state may impact flushing and biogeochemical connectivity of Arctic lagoon ecosystems.
