1940~2023年北极近地面风速变化的局地与环流驱动分析

Analysis of Local and Circulation Drivers of Arctic Near-Surface Wind Speed Changes from 1940 to 2023

摘要: 在北极放大效应持续增强的背景下，北极近地面风速发生显著长期变化，风速演变同时受到局地热力–下垫面过程和北半球大尺度大气环流的共同调控。基于1940~2023年ERA5再分析数据集，综合运用趋势分析、皮尔逊相关、偏相关、场回归诊断等统计方法，以60˚N以北北极区域为研究对象，分别解析北极升温引发的对流层低层稳定度改变、海冰消退带来的地表粗糙度变化对局地风速的调制作用，系统对比北极涛动(AO)、北大西洋涛动(NAO)、北极偶极子(AD)、太平洋–北美型(PNA)四类环流模态对北极风速的影响空间范围与季节差异。结果表明：北极升温与风速变化时空匹配度较高，升温通过降低对流层低层静力稳定度促进高空动量向下传输，该驱动效应在冬季最为突出；海冰消退造成地表粗糙度下降对风速的调制作用仅显著体现在夏季，秋冬季节该作用不明显。大尺度环流对风速调控存在明显空间和季节分异：AO对北极海域具备全域调控能力，年代际波动与北极风速年代际振荡高度同步；NAO影响主要集中于北大西洋海域，冬季信号最强；AD仅在春季对亚欧大陆北部边缘海产生显著作用；PNA的影响高度局地化，仅显著作用于白令海峡北部，冬春季效果明显。研究区分了局地过程与大气环流对北极风速的贡献以及各自的季节分工，可为理解北极海冰–大气相互作用提供科学依据。

Abstract: With the intensification of Arctic amplification, Arctic near-surface wind speed has experienced prominent long-term variations, which are jointly controlled by local thermal-surface processes and large-scale northern-hemisphere atmospheric circulation. Based on ERA5 reanalysis dataset covering 1940~2023, statistical methods including trend analysis, Pearson correlation, partial correlation and field regression diagnosis were adopted for the region north of 60˚N. This study analyzed the modulation effects of lower-tropospheric static stability change induced by Arctic warming and surface-roughness variation caused by seaice retreat on local wind speed. The spatial coverage and seasonal differences of wind speed regulated by Arctic Oscillation (AO), North Atlantic Oscillation (NAO), Arctic Dipole (AD) and Pacific-North American pattern (PNA) were systematically compared. The results show that spatiotemporal variations of wind speed match well with Arctic warming. Warming enhances downward transport of upper-air momentum by reducing lower-tropospheric static stability, and this effect reaches its maximum in winter. The modulation of wind speed caused by surface-roughness reduction due to sea-ice retreat is significant only in summer and becomes insignificant in autumn and winter. Large-scale circulation exhibits obvious spatial-seasonal heterogeneity in regulating wind speed. AO exerts pan-Arctic influence over Arctic seas, and its decadal fluctuation is highly consistent with decadal wind-speed oscillation. NAO mainly affects the North Atlantic Ocean with strongest signal in winter. AD has notable impacts on marginal seas of northern Eurasia only in spring. PNA shows highly localized effect that is significant only in northern Bering Strait, and works prominently in winter and spring. This paper distinguishes contributions to Arctic wind speed and seasonal division between local processes and atmospheric circulation, and provides scientific support for understanding Arctic sea-ice-atmosphere interaction.