Polar Cloud and Surface Classification Using AVHRR Imagery: An Intercomparison of Methods

Abstract

Six Advanced Very High-Resolution Radiometer local area coverage (AVHPR LAC) arctic scenes are classified into ten classes. These include water, solid sea ice, broken sea ice, snow-covered mountains, snow-free land, and five cloud types. Three different classifiers are examined: 1) the traditional stepwise discriminant analysis (SDA) method; 2) the feed-forward back-propagation (FFBP) neural network; and 3) the probabilistic neural network (PNN). More than 200 spectral and textural measures are computed. These are reduced to 20 features using sequential forward selection. Theoretical accuracy of the classifiers is determined using the bootstrap approach. Overall accuracy is 85.6%, 87.6%, and 87.0% for the SDA, FFBP, and PNN classifiers, respectively, with standard deviations of approximately 1%. Thin cloud/fog over ice is the class with the lowest accuracy (≈75%) for all of the classifiers. The snow-covered mountains, the cirrus over ice, and the land classes are classified with the highest accuracy (?90%) by all of the classifiers.