A case study of sea ice concentration retrieval near Dibble Glacier, East Antarctica: Contradicting observations between passive microwave remote sensing and optical satellites
Supervisor: Gunnar Spreen (University of Bremen)
In East Antarctica, around 136°E 66°S, spurious appearance of polynya (open water area within an ice pack) is observed on ice concentration maps derived from the ASI (ARTIST Sea Ice) algorithm during the period of February to April 2014, using satellite data from the Advanced Microwave Scanning Radiometer 2 (AMSR-2). This contradicts with the visual images obtained by the Moderate Resolution Imaging Spectroradiometer (MODIS), which show the area to be ice covered during the period. In this study, data of ice concentration, brightness temperature, air temperature, snowfall, bathymetry, and wind in the area were analysed to identify possible explanations for the occurrence of such phenomenon, hereafter referred to as the artefact. We find that the weather filters (Bootstrap filter and GR (36.5/18.7) filter) in the ASI algorithm have caused the error, and surface wetting could be the reason that the results were erroneously interpreted. A method to replace the erroneous pixels at the location with uncorrupted data, created by removing the weather filters at the specific pixels, was implemented. Furthermore, a general method to detect and remove possible erroneous pixels at other locations is proposed.