Estimation of freeze-thaw dates of a high latitude small lake using statistical analysis of SAR images

The aim of this paper is to estimate freeze-thaw dates of a small lake using Synthetic Aperture Radar (SAR) images. Here, the estimation of freeze-thaw dates is restated as a classification problem wherein each SAR image in the time series is classified as an ‘ice’ or ‘no ice’ image based on the presence or absence of ice on the lake. We implement and compare different methods consisting of various feature extraction algorithms and nonparametric classification schemes. We obtain the best classification accuracy using histogram information from SAR images applied to a Random Forest classifier. Correct classification rate in the range of 90% is seen in this case and a standard median filter is used to estimate the freeze-thaw dates from the classifier output. We also extend our analysis to the use of texture features and local statistics in solving this problem.