Tekst til bildet over: "The upper part shows a regular SAR-image from ESA's ERS-satellites for an area in the Yamal peninsula in northern Russia. The image shows an area with low terrain relief on land, and also a frozen ocean area. The lower image is an interferogram of the same are. On land the terrain relief can be easily seen. The ocean area in the SAR-image shows little information on the frozen ocean area, while in the interferogram ice floes can be easily distinguished, with relatively clear borders. Because these ice floes have been movin a few centimeters vertically with respect to each other, the resulting phase differences clearly show the outlines of the floes".