SAR ANALYSIS OF THE TERRA NOVA BAY ICE EDDY OF SUMMER 2015

摘要

In the framework of a study of new-ice formation inrnAntarctica, SAR image acquisitions were planned overrnTerra Nova Bay (TNB). Thanks to the ESA Third PartyrnMission program, Cosmo-SkyMed and Radarsat-2 imagesrnwere obtained for the period 20 February20 March,rn2015; in addition, available Sentinel-1 images over TNBrnfor the same period were retrieved from the ESA ScientificrnData Hub. The first inspection of the images revealedrnthe presence of a prominent eddy of surface ice, presumablyrninduced by the wind blowing from the continent.rnOur first goal was to investigate the correlation betweenrneddy area and wind field. Wind data were obtained fromrnthe AWS ‘Eneide’ located near the Italian Antarctic Basern“Mario Zucchelli Station” at TNB.rnFormeasuring the eddy area, we developed a specific processingrnscheme which consists of the following stages:rn1. Non-linear filtering; 2. Segmentation, based on thernMarkov Random Field theory, which uses a contextualrnapproach applied to both the original and the filteredrnimage; 3. Extraction of the eddy parameters, area andrnperimeter, by means of an active contour detection algorithmrnwhich works in an iterative way.rnThe correlation between eddy area and wind field wasrnanalysed by means of the Running Correlation Coefficientrnfunction R_(cc) which can reveal the consistency betweenrnthe two variables. R_(cc) attained high values in thernperiod 20 February 12 March; after March 15, a powerfulrnkatabatic wind completely disrupted the surface icerneddy and displayed a well-defined polynya.