The Research On Response Of Marine Eco-environment To Summer Arctic Cyclone Based On Remote Sensing

As common weather system in the Arctic,Arctic cyclones have happened 281 times every year.Summer Arctic cyclone strength show an increasing trend these years.It will bring disastrous effects on the Arctic ecosystem when Arctic cyclones strength are high.The Arctic cyclone will lead to the variation of marine ecological environment,with obvious changes in summer.When phytoplankton and sea surface temperature(SST)are anomalous,the sensitive and fragile Arctic ecosystem stability will be destroyed,and the Arctic creature even people living around the Arctic will be hurt.Hence,it is significant for Arctic ecosystem protection and marine disaster prevention to study the summer Arctic cyclone influence,and it is helpful for the research on the Arctic carbon flux and Arctic ocean acidification.In order to obtain the response of marine eco-environment to summer Arctic cyclones,firstly,we use sea ice concentration(SIC)provided by the United States National Snow and Ice Date Center(NSIDC),and Optimum Interpolation Sea Surface Temperature V2(OI.v2 SST)product provided by the Earth System Research Laboratory of NOAA from 1982 to 2017,and MODIS Chlorophyll-a(Chl-a)concentration provided by the Ocean Color Processing Center of NASA from 2003 to 2017 to study the yearly and seasonal variation of open water(open water area and the length of the open water season),SST and Chl-a concentration in the Arctic and its partitions.The variation of marine ecological environment is obtained;Secondly,according to the analysis results of the characteristics of marine ecological environment change,the cyclone case study is carried out in the regions with obvious changes in marine ecological environment,and the response characteristics of Chl-a concentration and SST under the influence of special cyclones are obtained,and the causes of the changes are analyzed in detail.Finally,according to the frequency of summer great Arctic cyclones,three typical sea areas are selected to calculate the changes of sea ice(sea ice concentration and sea ice area),Chl-a concentration and SST after several cyclones,and then we obtain the commonness and characteristics of environmental response and analyze the factors affecting marine environmental change.Long time series variation characteristics of marine environmental parameters:The results show that the open water area,the length of the open water season and SST in the Arctic and its partitions increases.The variation speed of the length of the open water season in the Greenland Sea is the fastest,followed by the Kara and Barents Seas,and then by the Arctic Ocean.The Chl-a concentration in the Arctic exhibits a slowly increasing trend from 2003 to 2017.Among nine partitions,the Chl-a concentration in Kara and Barents Seas is the largest and the Chl-a concentration increasing trend is most obvious.There is a significant positive correlation between the open water area,the length of the open water season and SST from 1982 to 2017 in the Arctic and its partitions,and the SST effects on open water are closely related to latitudes.We find that no significant correlation exists between the open water and Chl-a concentration in almost partitions,which may be due to the change of Chl-a concentration is mainly affected by other factors(nutrients and light,etc.).Case analysis of Arctic cyclones:Based on 8-day Chl-a concentration from the European Space Agency(ESA)and daily Optimum Interpolation Sea Surface Temperature(OISST)form NOAA,we study the response of Chl-a concentration and the SST before and after the transit of two cyclones which occurred in Kara Sea and Greenland Sea.It shows that after the Arctic cyclone transiting,Chl-a concentration increases and SST decreases.The changes of Chl-a concentration and SST are contributed to Arctic cyclones passing,wind stress increasing,vertical mixing enhancing,Entrainment and upwelling enhancing.Above reasons bring the lower layer sea water which are nutrient-rich to surface.As a result,Chl-a concentration and SST change dramatically in a short time.The variation Nearshore Chl-a concentration and S ST is higher than the continental shelf and deep sea,mainly due to precipitation and runoffResponse characteristics of marine ecological environment to Arctic cyclones in typical sea areas with long time series:We use reanalysis dataset provided by the European Centre for Medium-Range Weather Forecasts(ECMWF)to calculate times of summer great Arctic cyclone.We find that the number of summer great Arctic cyclones in Greenland Sea,Kara and Barents Seas,and the Arctic Ocean,accounting for 82%of the total number of Arctic cyclones.After cyclones passing,Chl-a concentration in these three regions increase,SST in Kara and Barents Seas,Greenland Sea decreases while SST in the Arctic Ocean increases.The initial mixed layer depth,initial Chl-a concentration,and cyclone intensity factor will affect the variation of Chl-a concentration.A significant correlation exists between the initial Chl-a concentration and Chl-a concentration increases in the Greenland Sea and the Arctic Ocean.The variation of the SST in the Arctic Ocean is affected to initial MLD,initial SST and initial SIC.We propose that SIC responsibility and sea ice area responsibility can be used to qualify the impact of Arctic cyclones on sea ice reduction,the higher the value is,the greater the effect of cyclone on sea ice reduction.The main highlights of this research are as follows:the variation characteristics of Arctic marine ecological environment parameters in long time series are obtained;the impact of two special Arctic cyclones with different intensity on marine ecological environment in regions where the parameters of the marine ecological environment is obtained,and the impact mechanism is analyzed;We further obtain the impact of Arctic cyclones on marine ecological environment in different sea areas in long time series,and quantify the effects of Arctic cyclones on sea ice.The above work lays a foundation for further quantifying the impact of Arctic cyclones on marine ecological environment and contributes to the study of stability assessment of marine ecosystems.