Response Of Sea Ice Concentration To Climate Change In The Northeast Asian Marginal Sea

The decrease in sea ice concentration and thickness,as well as the structural characteristics of sea ice,are changing in response to global climate change.The decrease in sea ice concentration exacerbates ocean warming under global warming,which in turn makes the sea ice melt faster and eventually leads to various natural disasters such as sea level rise.This also indicates that there is an obvious positive feedback effect between global climate change and sea ice concentration change.In this paper,we analyze the changes of sea ice concentration in Northeast Asia based on the sea ice density data of the National Snow and Ice Data Center(NSIDC)from 1980 to2020,this paper investigates the response relationships between sea ice concentration changes in the Northeast Asian marginal sea,sea ice changes in the Northeast Asian marginal sea and climate elements,and the main conclusions obtained are:(1)Sea ice concentration reflects the extent of sea ice coverage in the region,and describes the spatial density of sea ice to elaborate the characteristics of sea ice.If we want to quantify the sea ice in the region,we need to calculate the sea ice extent and area.In the data statistics,the sea ice density in the Northeast Asian marginal sea roughly reaches the maximum in March and the minimum in September;and the sea ice density reaches 30%-80%in winter and spring,and the sea ice density in summer and autumn is less distributed in Northeast Asia,but still more widely distributed in the Arctic.In recent years,the extent and area of sea ice in the Northern Hemisphere has been less than 14×10~7km2.The rate of decline of sea ice area reaches 161.18km~2/day,while the decline of sea ice extent reaches 176.93km~2/day.Among them,the Sea of Japan is the least dense ocean within the 3 seas,with an average sea ice extent of less than 3000km2;the Sea of Okhotsk is the largest sea ice extent,with an average of more than 4000km2per month.However,according to the trend of sea ice changes in the region,the sea ice extent in the Sea of Okhotsk decreases the most at 26.85 km~2/day;the sea ice extent in the Bering Sea decreases the second fastest at 15.89 km~2/day;and the smallest in the Sea of Japan is only 2.46 km~2/day.(2)The spatial and temporal variability characteristics of sea ice and climate change characteristics of the Northeast Asian marginal seas were analyzed one by one by using the one-dimensional linear regression analysis method.The decline of sea ice density in Sea of Okhotsk is the most obvious,and its spatial and temporal variation characteristics are not consistent with the sea ice variation in Bering Sea.At the same time,sea ice in Sea of Okhotsk shows a significant decrease in winter and spring,and the trend of sea ice decrease is the largest in April;sea ice in Sea of Okhotsk and Arctic Sea ice had synchronous changes,mainly because both of them are closely related to the change of Arctic temperature,which can control the change of sea ice in Sea of Okhotsk to some extent by influencing the change of air temperature over Sea of Okhotsk.In the Bering Sea and the Sea of Japan,sea ice decreases fastest in March,and the trend of sea ice extent in winter is not obvious in both of them.The results show that there are different transition characteristics and years of anomalous changes among different seas.During the reanalysis of climate change,temperature,sea surface temperature and cloudiness all have distinct regional characteristics.The increase of temperature is 2℃/10a,and the overall change of sea surface temperature is consistent with 2m temperature,which also shows an upward trend,but the upward trend of sea surface temperature is smaller than 2m temperature,reaching 1.5℃/10a.And cloud amount is also an important factor of sea ice change,and its change characteristics are mainly based on the decrease of cloud amount at high latitudes,and the decrease trend is about 5%/10a,among which the change trend most complex in the 2000s,during which the fluctuation of cloud amount fluctuates greatly due to the appearance of other natural conditions.(3)Using the correlation analysis method,we initially explored the climate factors affecting the sea ice variability characteristics of each sea area in Northeast Asia.The results show that,according to the interpolation analysis of sea ice concentration and meteorological data of long time series,the trends of sea ice change are negatively correlated with 2m temperature and sea surface temperature at 95%confidence level,the correlation coefficient between sea ice extent and temperature is-0.8286,and the correlation coefficient between sea ice extent and sea surface temperature is-0.5357 and the positive correlation with cloud volume,and the correlation coefficient is 0.4653.Sea ice variability is most influenced by 2m temperature,followed by sea surface temperature,The correlation with cloud amount is the least.The relationship between sea ice change and climate elements also needs to consider a combination of other factors,so the response relationship between sea ice change and other climate elements needs to be further studied.At present,most of the studies on sea ice change in China focus on the poles or the Yellow and Bohai Seas,but there are few studies on sea ice change in the Northeast Asian marginal seas.This paper provides a scientific basis for coping with climate change and promoting sustainable development in the Northeast China Transboundary Region;it also provides a theoretical basis for China to ensure the establishment of an outlet in the Northeast Asian marginal sea by carrying out the research on sea ice monitoring in the Northeast Asian marginal sea.