Research On Sea Ice Condition Of Arctic Passage In 1979-2017

Arctic passage is the shortest route to connect European,Asia and North American Economic zones,so it has important commercial value and strategic significance.China is an important maritime trading country,the development and utilization of the Arctic Passage will greatly reduce the transportation cost.The Party's 19th CPC National Congress report emphasize the importance of speed up the building of a powerful marine power,putting the plan to manage the polar regions and build the polar power as one of the core contents to build the powerful marine power,and defining the Arctic Passage as "the Silk Road on Ice" for the construction of "Belt and Road".The biggest difference between the Arctic Passage and other warm waterways is the existence of sea ice,so the study of ice condition in Arctic Passage is significance to opening of the Passage.Using the sea ice concentration comes from NSIDC sea ice index and sea ice thickness comes from ESA CryoSat-2 to estimate the trends of sea ice extent,area and sea ice thickness in Northeastern and Northwestern Arctic.On the basis of the Northeast Passage and Northwest Passage extracted from VOS database,in virtue of high-resolution AMSR-E/2 sea ice concentration to judge the first and the end navigable day and opening days by setting 30%concentration as navigable threshold.Combined with the sea ice thickness in the thin ice region from SMOS to discuss the detailed characteristics of throat section of Passage.We quantified the variation trend of 30%concentration contours,which provides the basis for the possibility of North Pole Passage opening,and discussed the impact of atmospheric factor on Arctic Passage.The sea ice extent and area in Northeastern and Northwestern Arctic changed periodically from 1979-2017.The amplitude in Northeastern Arctic increased after 2005,while in Northwestern Arctic increased after 2007.It is high value period of sea ice extent and area from January to April,and low value period from July to October.The sea ice extent and area decreased in Northeastern and Northwestern Arctic,and the decreasing rate of Northeastern Arctic was faster than Northwestern Arctic.The minimum sea ice extent of Northeastern and Northwestern Arctic appeared in 2012,the sub-minimum appeared in 2007 and 2016 respectively.However,the sea ice area in Northwestern Arctic in 2016 is smaller than that in 2012,which is closely related to the continuous decrease of sea ice concentration.The Barents Sea and Norwegian Sea section in Northeast Passage is navigable almost throughout the year,while the ice condition is the most complex and the navigability is the worst around the Severnaya Zemlya,which is the key to affecting the navigation of Northeast Passage.In the last 10 years,the ice condition near the Severnaya Zemlya has improved significantly,Villiquetsky Strait is the best navigable in the all Strait near the Severnaya Zemlya.Before 2000,the eastern Siberian Sea in west of De Lang Strait was only a few years navigable and needed to sail close to the continent.After 2000,the navigable sea area was extended obviously to high latitudes.The Baffin Bay section in north routes of Northwest Passage has a longer navigation time,and the west of Amundsen Bay is also less affected by the ice cover.In addition,the navigable sea area was also gradually extends to the high latitude.The section between the Barrow Strait and the M'Clure Strait often has ice barriers.In recent years,the location of ice barrier is moving westward.The annual variation of opening time of the whole Passage is larger,not only relate to the sea ice area,but also with the sea ice movement mode.For example,the sea ice area is small in 2007,while the strong northwest wind in the Laptev Strait in summer caused the sea ice to move to shore,leading to the sea ice congesting in the north of Taymyr peninsula,resulting in navigate difficultly in Severnaya Zemlya.But on the whole,the start navigable day was advance by 0.85d/yr.,and the end navigable day was delayed by 0.73d/yr.In the past 10 years,the navigability of the Northeast Passage has obviously enhanced,the start navigable day was fluctuated greatly from the end of July to the end of August,while the end navigable day was relatively stable,generally in the early or middle of October.If we take the sea ice thickness is less than 30cm as navigation condition,the end navigable day will be delayed to the late of October or the early of November.The navigability of the South Route was obviously superior to North Route in Northwest Passage,the navigable years of the North Route is less,and the navigability was the best in 2010-2012,the opening days reached more than 50 days,the advance rate of the start navigation day is far greater than the delayed rate of the end navigation day,it was 0.9 d/yr and 0.25d/yr.respectively.The south route was not opened in 2003,2004 and 2005,and was only 16 days opened in 2014,the navigable days were least 30-40 days and most 60-70 days.The Furuihe Carat Strait opened earlier on South Routes,but was prone to repeated ice jams.The ice condition along James Ross Strait to Rey Strait to Simpson Strait is lighter and more navigable than the Victoria Strait in Passage section from Larsen Strait to Queen Maud Gulf.The day of minimum sea ice area in Arctic usually occurs in early or middle September.The minimum sea ice area and the average concentration continually refreshed in Arctic.Although the minimum sea ice area in 2016 was slightly larger than that in 2012,the average concentration in 2016 was about 6.8%less than in 2012.The contour of 30%sea ice concentration retreated continuously in summer from 1979 to 2017,with the fastest shrinking rate in August and September,it was-12.8km/yr.and-11.9km/yr respectively.Then in less than 40 yeras,the south of 85° N in August and September will be navigable,and the navigable route will be close the Polar Passage.The variation of Arctic sea ice area is closely related to Sea Surface Temperature anomaly,Sea level Pressure and wind field.The increase of temperature promotes the melting of sea ice,and influences the change of wind field together with the pressure.The wind field cause the sea ice converges and diverges,the distribution of sea ice has an important influence on the navigability of Passage.