# Satellite SAR Data-based Sea Ice Classification: An Overview
## 3 Interactive Sea Ice Charting: GIS-based Techniques  
CIS designed an image display system that comprises a series of servers and workstations as well as GIS software. The integrated system can geocode, pre-process the image, combine a few images to form of mosaic and draw lines to define homogeneous ice zones in the image. Ice charts are drawn for the Canadian Arctic, using all available satellite information, as well as visual ice observations in situ. The U.S. NIC uses SAR data (as well as other information) to provide routine ice thickness estimation, a daily ice edge and marginal ice zone hemispheric analysis via GIS tools. Detailed hemispheric analysis of sea ice types and concentrations is performed weekly in Sea Ice Grid (SIGRID) format [11]. Ice products provide information on sea ice stage of development according to WMO ice nomenclature. The NIC has an active collaboration with the CIS [12]. Finnish Ice Service (FIS) employs satellite data for mapping ice conditions in the Baltic Sea, using GIS-based software to enable the processing of satellite SAR information. Interpretation of satellite images is performed by experienced ice experts using GIS technology to polygonize the sea ice areas of the same attributes. This technique requires many ground truth measurements and continuous monitoring of ice conditions. Operative ice information includes daily ice analysis charts, ice thickness analysis, ice model forecasts, etc. Daily ice charts are based on the ice chart of the preceding day, SAR images, observations from icebreakers and coastal stations, and include concentration, typical, maximum and minimum thickness of level ice and a numeral on a five-point scale for ice ridging. This technology has been developed for the Baltic Sea and is currently being developed for the Kara and Barents Seas. In addition, it will be extended to the other arctic seas [13]. The GIS-based system developed at the Danish Meteorological Institute (DMI) efficiently produces digital ice charts in vector format for the Greenland waters using SAR and other satellite data. The ice service at the Norwegian Meteorological Institute routinely processes a greater volume of satellite remote sensing data and mainly focuses on the operational analysis of ice conditions for producing ice charts containing sea ice concentration and delineated areas of fast ice. The Norwegian Ice Service provides ice charts for the European part of the Arctic every weekday. The charts are produced by a manual interpretation of Sentinel-1 (S1) and RS-2 SAR data [12]. In 1975, a concept and beta version of the Automated Ice Information System for the Arctic (ALISA) was developed at the Arctic and Antarctic Research Institute (AARI, St. Petersburg, Russia) [14]. One of the Automated Working Places (AWPs) of this system, AWP \"Ice Expert\", has been designed to produce the ice information products. GIS-based software AWP \"Ice Expert\" operates with various satellite information comprising ice information from ground-based and drifting hydrometeorological stations, vessels and icebreakers. This comprehensive information analysis with the previous analysis (ice chart) as the background state allows producing new information products (annotated satellite images and ice charts) by experienced sea ice experts. The polygons of areas with homogeneous ice attributes are labeled by the ice expert and the resulting image is automatically saved in the WMO SIGRID3 standard vector format [11]. The developed automated technique allows working directly in the ArcView GIS environment and compiles the ice chart immediately as a vector shapefile containing information about the boundaries of ice zones and the ice attributes (\"ice eggs\") within each zone. Russian State Research Center for Space Hydrometeorology \"Planeta\" (Moscow) has conducted radar surveys of the Arctic and Antarctic ice cover since 1983 after the launch of the first oceanographic satellite Kosmos-1500. \"Planeta\" provides digital charts of ice coverage conditions for the Arctic seas based on satellites data.