Research On The Arctic Sea Ice Thickness Retrieval Algorithm Based On CryoSat-2 Satellite Data

Sea ice of the Arctic is extremely sensitive to climate changes and variability.Sea ice thickness is an important parameter that regulates the heat exchange between the Arctic ocean and the atmosphere,the degree of sea ice deformation,and the sea ice cycle.It is also one of the important factors of determines its thermodynamics and dynamics.Therefore,it is important to measure the distribution of sea ice thickness in the Arctic Ocean.The CryoSat-2 satellite radar altimeter has the advantages of large scale,all weather and all day time,and can accurately measure the floating ice of different scales in the Arctic waters,which has become a very reliable and feasible method for studying the changes of polar sea ice.Based on the satellite SAR model waveform data,this paper conducts research on Arctic sea ice thickness.The main research contents are as follows:(1)Identify surface types in Arctic sea ice regions.The waveform characteristics of the CryoSat-2 satellite SAR mode are analyzed,and 12 commonly used waveform characteristic parameters are summarized.The pulse peakiness,the stack standard deviation,and Early tail to peak power ratio are better than the three identification parameters,and their combinations and threshold values are used.The method can realize the accurate identification of sea ice surface types,which are mainly divided into three types:one-year ice,multi-year ice,and Leads.(2)Calculating reliable instantaneous sea surface height.Through Lead identification,the distance weighting method is used to interpolate the sea surface height anomalies at the sea ice location or the Lead water surface within a certain distance from the location to obtain reliable instantaneous sea surface height.(3)Retrieve of sea ice freeboard and sea ice thickness.Based on the surface type identification,the difference between sea ice elevation and instantaneous sea surface height is used to calculate the ice freeboard,and the hydrostatic balance formula is used to retrieve the sea ice thickness in the Arctic sea ice region from 2015 to 2018.IceBridge data to verify the results and conduct trend analysis.The research results show that the comparison between the calculation results in this paper and the annual IceBridge field flight data shows that the results in this paper and the verification data are more consistent in the monthly average and the overall change trend.The continuous thinning of the Arctic multi-year ice area is the main factor causing the average thickness of Arctic sea ice to continue to decline.The comparison results prove that the research method in this paper is feasible and can be used to obtain reliable and continuous sea ice thickness and change information.