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本文将65°N以北500 hPa位势高度的正异常环流定义为北极反气旋环流(Arctic anticyclonic circulation, AAC)。采用百分位阈值法筛选出641 d极端北极反气旋环流事件(Extreme Arctic anticyclonic circulation, EAAC),发现EAAC在冬季(12月至次年3月)发生频次最多、强度最大，呈显著上升趋势。北极太平洋扇区、大西洋扇区和欧亚扇区的EAAC发生日数依次减少。三个扇区的EAAC的加强及EAAC与“暖北极-冷大陆(Warm Arctic-cold continents, WACC)”模态的联系，均可能与高空急流异常变化调制中高纬度罗斯贝波的发展有关。对于太平洋扇区，由于东亚-北太平洋急流出口区的纬向风减弱有利于阿拉斯加长波脊的发展加强并向北极入侵，造成北极太平洋扇区EAAC的加强和“暖北极”分布，脊东西两侧由极涡分裂南下的切断低压携带的冷平流有利于“冷大陆”的形成。北大西洋急流出口区纬向风在急流轴北侧减弱、南侧加强，导致气旋式切变涡度增大，这种高空辐合形势有利于格陵兰地区长波脊的发展加强，进而引起北极大西洋扇区EAAC的加强和WACC的形成。欧亚中纬度高空西风急流的异常向北加强及其北侧的东风异常，有利于罗斯贝波的向北传播和高空气旋式切变涡度增大，促使北极极涡向欧亚一侧偏移，从而可能导致北极欧亚扇区EAAC的加强和WACC的形成。该研究为理解北极气候变化与中纬度气候变化的联系提供了新视角。
Abstract：This paper defines the positive anomaly of 500 hPa geopotential height north of 65°N as Arctic anticyclonic circulation(AAC). Using the percentile threshold(95th) method, 641 days of extreme AAC(EAAC) events are identified. EAAC occurs most frequently and intensely in winter(December to March), showing a significant upward trend, with occurrence days decreasing in the Pacific sector, the Atlantic sector, and the Eurasian sector of the Arctic. The strengthening of EAAC in these sectors and its linkage with the "warm Arctic-cold continents"(WACC) pattern are associated with abnormal upper-level jet stream changes modulating Rossby wave development at middle-high latitudes. In the Pacific sector, weakened zonal winds at the East Asian-North Pacific jet exit enhance the Alaska ridges, leading to "warm Arctic" conditions; cold advection from cut-off lows forms "cold continents". In the North Atlantic, asymmetric zonal wind changes at the jet exit increase cyclonic vorticity, strengthening the Greenland ridges and inducing EAAC and WACC. In Eurasia, a northward-shifted westerly jet and anomalous easterlies promote Rossby wave propagation, enhancing cyclonic vorticity and shifting the polar vortex, thus strengthening EAAC and forming WACC. This study offers a new perspective on Arctic-midlatitude climate linkages.
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基本信息:
DOI：10.16441/j.cnki.hdxb.20250086
中图分类号:P434;P941.62
引用信息:
[1]张涵,赵传湖,杨宇星,等.极端北极反气旋环流的频发加强及其与“暖北极-冷大陆”模态的联系[J].中国海洋大学学报(自然科学版),2026,56(02):13-24.DOI:10.16441/j.cnki.hdxb.20250086.
基金信息:
国家自然科学基金项目(42430411,42075024); 中央高校基本科研业务费专项(202561001)资助~~
2026-02-02
2026-02-02