October 26, 2014
Vestisen Glacier is the second largest glacier of the Oksindan Icecap flows west. The glacier drains west into the Rossaga River, which has a Statkraft Hydropower plant, though upstream of the glacier inflow. Here we examine Landsat imagery from 1992-2014 to observe recent changes.
Vestisen Mapcarta view
In 1994 the glacier terminus is at the red arrow. The areal extent of snowcover is more than 50% of the glacier area, blue arrow. A small glacier to the north is connected to the Vestisen at the pink arrow. The purple arrow is a small bedrock ridge that intrudes into the glacier a small distance from the south, and the yellow arrow is a small side terminus of the glacier. In 1999 the snowcovered area is 35% of the glacier. The region of firn, snow that survived the first summer, but is not ice yet, green arrow, is extensive suggesting that the 1999 mass balance was more negative than recent years. In 2006 the ridge at the south edge of the glacier has expanded at the purple arrow. At the pink arrow the connection to the glacier to the north is still comprised of glacier ice. In early september of 2014 the snowcovered area is very low at 15-20% of the glacier. The glacier has separated from the glacier to the north at the pink arrow. A small outcrop of rock has appeared amidst a secondary terminus at the south side of the glacier, yellow arrow. The ridge intruding into the southern edge of the glacier is now 300-400 meters longer and is wider. A lake has formed at the main terminus. This lake has formed due to a combination of thinning and retreat of the terminus, a retreat of 250-300 m has occurred. The Mid-September 2014 image indicates the snowcovered area, blue arrow is down to 5%. The firn area, green arrow, that represents snow that had survived previous summers, is being consumed by the substantial melt of the 2014 season. To have an equilibrium mass balance glaciers in Norway need to be 55-60% snowcovered at the end of the melt season. Glacier mass balance will be quite negative in 2014, which will lead to further retreat of the main terminus and secondary terminus regions, NVE will continue its long term mass balance monitoring that will report on the particular quantities. The retreat here is less than that of Austsre Oksindbreen, just to the northeast, but it is poised for greater retreat in the near future, with poorer retained snowcover. The glacier is following a pattern of thinning and retreat over the last 15 years in Norway. The Norwegian Water Resources and Energy Directorate (NVE) reports that 23 of 24 Norway glaciers examined consistently since 2000 have retreated significantly.
1994 Landsat image
1999 Landsat image
2006 Landsat image
2014 early September Landsat image
2014 Late September Landsat image