Study On The Variation Of Hulun Lake Ice In Recent 30 Years And Its Influencing Factors Based On Remote Sensing Image

The environmental impact of global climate change has always been one of the important issues concerned by researchers at home and abroad.The impact of global temperature rise on sea ice and lake ice is becoming more and more obvious.Lake ice as a regional climate indicator can better respond to global climate change.At present,there are few studies on lake ice at home and abroad.Remote sensing method can monitor the lake ice on a large scale and a long time scale,so this paper uses remote sensing to monitor the changes of ice in Hulun lake.from the inversion of satellite image,we get the trend of lake ice change.In this paper,we select the lake ice image from 1986 to 2017,and extract the time of lake ice freezing,the time of complete freezing,the time of thawing,the time of thawing,the time of freezing,and the time of thawing.Four parameters of complete thawing time were used to analyze the changing trend.The results showed that the freezing time of Hulun Lake was usually from the end of October to the beginning of November,and the average time from the beginning of the freezing to the complete freezing was 4 to 5 days.The melting time is usually in early April or mid-April of the following year,the average melting ice period is about 30 days,and the lake ice completely melts in early May or early May.From the 30 years from 1986 to 2017,The Complete freezing period of Hulun Lake is shortened by an average of 15.9 days,the time of complete ice formation was delayed by 8.4 days on average,and the time of complete melting was advanced by 10.2 days on average.The ice forming time of lake ice tends to delay,while the melting time tends to advance,and the time of freezing is also shortened.the inversion of the lake ice thickness in a specific year has been carried out.By comparing the remote sensing inversion with the measured data,it is found that the lake ice in Hulun Lake keeps a continuous thickening state from the early ice forming stage until the the Mid-February,when it reaches the thickest.The thickest thickness of the lake ice is between 1.3~1.5 meters on average,which began to thinning from the end of March.With the gradual melting of the lake ice,the thickness of the ice also decreased,and then completely melted.In order to monitor the accuracy of ice thickness inversion by remote sensing,the Zubov model is used to verify the measured ice thickness data.It is found that the correlation between the inversion ice thickness and the measured ice thickness is about 0.8,and the correlation between the measured ice thickness and the ice thickness simulated by Zubov is about 0.76.It shows that this method has high precision and good effect.after getting the change trend of lake ice clearing,the factors that may affect lake ice are considered synthetically,and the main factors are air temperature and wind speed and wind direction.Because the temperature has been rising gradually in the past 30 years,The decrease of accumulated negative accumulated temperature in winter of Hulun Lake has a direct impact on the lake ice clearing.Meanwhile,wind speed and wind direction have a certain influence on the formation and ablation of lake ice,and other influencing factors include lake water salinity and lake bottom landform.Lacustrine morphology factors also have a certain impact on lake ice.