Validation and complementing of SAR satellite surveys over Arctic Sea ice by multiple simultaneous sets of measurements

摘要

Combined satellite surveys and in situ sea ice observations are crucial for the calibration and validation of data retrieved from satellite products. However, coordinated campaigns with spatially and temporally coinciding high resolution satellite surveys and ground and airborne sea ice surveys are rare. Between 2010 and 2012, in situ observations on Arctic sea ice were performed both in spring and summer in different Arctic regions: north of Svalbard at the edge of the Arctic Basin, in the western Fram Strait, and at coastal fast ice sites off Svalbard and Alaska. High resolution Radarsat-2 SAR images were obtained in both dual and quad polarization modes. Simultaneously, data about sea ice and snow thickness, ice topography, and the area of melt ponds was collected, along with ship-based regular ice observations. Ice thickness surveys were performed using a helicopter-borne electromagnetic device, accompanied by digital photography and laser altimetry. Data on snow and sea ice properties including densities, thicknesses, freeboard, have been collected over several years for calibration of satellite altimetry. These are necessary background data for estimating the sea ice thickness from the measured freeboard. The preliminary results indicate the improved possibilities for ice type classification from SAR satellite imagery. Advanced segmentation techniques of multipolarized SAR products were performed on scenes with simultaneous in situ observations, and possibilities, limitations, and implications for use in operational services as well as for climate science are discussed.