加拿大北极群岛区域西北航道海冰冰情长期时空变化特征研究

LONG-TERM SPATIAL AND TEMPORAL VARIATIONS OF SEA ICE IN THE NORTHWEST PASSAGE OF THE CANADIAN ARCTIC ARCHIPELAGO

加拿大北极群岛西北航道区域海冰冰情对西北航道的开通及航行安全有着显著的影响。本研究将西北航道分为南部、北部以及交汇区3个区域,利用美国国家冰雪中心Bootstrap海冰密集度数据和CryoSat-2、CS2SMOS观测以及高分辨率北极海洋-海冰耦合模型(AO-FVCOM)的海冰厚度数据对1978年11月—2017年12月加拿大北极群岛区域西北航道海冰冰情长期时空特征进行研究,并对南线和北线冰情进行评估。研究结果显示西北航道冬春季被高密集度的海冰覆盖,夏秋季密集度较小,呈现北高南低的分布特征;北部、南部、以及交汇区域覆盖范围呈现减少趋势,分别为–0.01×10^5km^(2)·(10a)^(–1)[–0.77%·(10a)^(–1)]、–0.09×10^(5)km^(2)·(10a)^(–1)[–3.50%·(10a)^(–1)]以及–0.12×10^(4)km^(2)·(10a)^(–1)[–2.81%·(10a)^(–1)];海冰厚度在北部和南部区域呈现减小趋势,分别为–0.25 m·(10a)^(–1)和–0.13 m·(10a)^(–1)。西北航道南线冰情优于北线,海冰密集度、覆盖范围、厚度均小于北线。对影响海冰密集度和厚度的大气和海洋热力学因素进行分析发现,研究区域的表面大气温度、海洋表层温度呈现上升趋势,并和海冰密集度呈现显著负相关,和北部、南部区域海冰厚度呈现显著负相关,与交汇区域海冰厚度相关不显著。

Navigation through the Northwest Passage of the Canadian Arctic Archipelago is heavily influenced by sea ice conditions.The model domain used in this study was divided into the northern,southern and intermediate areas.We studied the spatial and temporal characteristics of sea ice in the Northwest Passage between November 1978 and December 2017 and evaluated the ice conditions of the northern and southern routes by using Bootstrap sea ice concentrations from the National Sea and Ice Data Center(NSIDC)and sea ice thicknesses from CryoSat-2,CS2SMOS and Arctic Ocean-Finite Volume Community Ocean Model(AO-FVCOM).Over the study period,sea ice concentration in the Northwest Passage was high in winter and spring,low in summer and fall,high in the north,and low in the south.Sea ice extent has decreased by–0.01×10^(5)km^(2)/decade(–0.77%/decade)in the northern area,–0.09×10^(5)km^(2)/decade(–3.50%/decade)in the southern area,and–0.12×10^(4)km^(2)/decade(–2.81%/decade)in the intermediate area.Sea ice thickness has decreased by–0.25 m/decade in the northern area and–0.13 m/decade in the southern area.Between November 1978 and December 2017,sea ice concentration,extent and thickness along the southern route were lower than those along the northern route.Ice conditions along the southern route were safer for navigation.We analyzed atmospheric and oceanic thermodynamic parameters that influence sea ice concentration and thickness.Surface air temperature and sea surface temperature in the study area have increased and are significantly and negatively correlated with the sea ice concentration and thickness of the northern and southern areas.However,there are no significant correlations between temperatures and sea ice thickness in the intermediate area.