ON THE GLACIOLOGY OF EDGEOYA AND BARENTSOYA, SVALBARD

The ice masses on Edgeoya and Barentsoya are the least well known in S valbard. The islands are 42-47% ice covered with the largest ice cap, Edgeoyjokulen, 1365 km(2) in area. The tidewater ice cliffs of eastern Edgeoya are over 80 km long and produce small tabular icebergs. Sever al of the ice-cap outlet glaciers on Edgeoya and Barentsoya are known to surge, and different drainage basins within the ice caps behave as dynamically separate units. Terminus advances during surging have punc tuated more general retreat from Little Ice Age moraines, probably lin ked to Twentieth Century climate warming and mass balance change. Airb orne radio-echo sounding at 60 MHz along 340 km of flight track over t he ice masses of Edgeoya and Barentsoya has provided ice thickness and elevation data. Ice is grounded below sea level to about 20 km inland from the tidewater terminus of Stonebreen. Ice thickens from <100 m c lose to the margins, to about 250 m in the interior of Edgeoyjokulen. The maximum ice thickness measured on Barentsjokulen was 270 m. Landsa t MSS images of the two islands, calibrated to in-band reflectance val ues, allow synoptic examination of snowline position in late July/earl y August. Snow and bare glacier ice were identified, and images were d igitally stretched and enhanced. The snowline was at about 300 m on th e east side of Edgeoyjokulen, and 50-100 m higher to the west. Snowlin es were at approximately 450 m on Digerfonna and Storskalven. On Baren tsjokulen the snowline was 350 m above sea level on the eastern flank and over 400 m on the west. This asymmetry suggests greater precipitat ion on the east side of the ice caps. Enhanced Landsat imagery was als o used to identify suspended sediments in the waters offshore of the i slands. Where this turbid meltwater emerges from tidewater glacier ter mini, it is likely to be derived from the subglacial drainage system. This suggests that at least parts of the beds of the ice masses on Edg eoya and Barentsoya are al the pressure melting point, and that a basa l hydrological system is present.