北极航道的通航网络识别方法与变化趋势分析
Identification methods and trend analysis of navigable network in Arctic shipping routes
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摘要: 全球气候变化的趋势使北极航道的通航潜力不断提高,对北极航道通航能力的识别与变化趋势研究对于北极国家以及中国均有重要的意义。基于中国风云三号卫星(FY-3B/C/D)北极海冰密集度(SIC)和SMOS海冰厚度(SIT)遥感数据,提出了一种基于图像形态学算法的通航网络识别方法,实现了2011年至2022年北极东北、西北、中央航道逐日通航路径提取,并分析了通航时间窗口和相对通航里程的变化趋势。对近12年逐日通航路径进行了识别和对比研究,结果表明:1)基于本文方法识别通航网络,可有效减小连通性矩阵的规模,提升航道通航情况计算效率,并可获得多条备选航线,为航线优选提供参考;2)以40%的海冰密集度、0.5米的海冰厚度为可通航范围阈值,北极航道在近12年内均出现通航窗口,其中东北航道具有较高的开发价值,其通航窗口有扩大趋势,但开通的起止时间仍有较大的不确定性;3)北极西北和中央航道的距离成本比东北航道更有优势,若未来出现定期通航的窗口期也有望缩短大西洋至太平洋之间的航程。Abstract: The trend of global climate change has increased the navigation potential of the Arctic shipping routes.Identifying the navigable passages and understanding the navigability trend of the routes is of great value to Arctic countries as well as to China.In this paper,based on the remote sensing data of Arctic Sea Ice Concentration(SIC) from China’s Fengyun-3 satellites(FY-3B/C/D) and Sea Ice Thickness(SIT) data from SMOS mission,a method for identifying navigable network is proposed based on image morphological algorithm,which is used to extract the daily navigable passages of the northeastern,northwestern and central Arctic shipping routes from 2011 to 2022.Moreover,the variation trend of navigable time window and the relative mileage are derived.Through the analysis of day-by-day navigable passages in the past 12 years,the results show that:1) The proposed identification method can effectively reduce the size of connectivity matrix,and improve the computational efficiency in identifying navigable sea ice channels by providing multiple alternative paths for route optimization;2) With 40% sea ice concentration and 0.5 m sea ice thickness as the navigable range threshold,the Arctic shipping routes have navigable time window for every year in the past 12 years.Among which,the Northeast Passage has the highest development value,and its navigable time window has a tendency to expand,but the starting and ending time of opening is still unstable;3) The Northwest Passage and the Arctic Central Route have more advantages than the Northeast Passage in terms of distance cost,and it is expected to shorten the voyage distance between the Atlantic and the Pacific Ocean if there were regular navigable time window in the future.