Modeling of Svartisen Ice Cap, Northern Norway, Using In-situ Observations and Remote Sensing of Ice Velocity and Volume Changes

Abstract:

We model the evolution of Vestre Svartisen. Vestre Svartisen is located in northern Norway and is the second largest ice cap in Norway with an area of 218 km². There is an abundance of in-situ observations for this ice cap as a result of the monitoring programs in relation to hydro-power generation. Based on these in-situ observations, we can use the case of Vestre Svartisen to test the performance of glacier evolution modeling based on remote sensing, that provides data on glacier volume and surface velocity changes, instead of in-situ observations that only are available for a limited number of glaciers world-wide. The in-situ observations at Vestre Svartisen include mass balance observations since 1970 on Engabreen catchment and 10 mass balance years on Storglombreen, a glacier length record of Engabreen back to 1600, outlines of the ice cap in 1968, 1988 and 1999, ice thickness observations, and surface velocity measurements. In addition to these in-situ observations, we derive glacier volume and surface velocity changes from ASTER and Landsat imagery, respectively. We model the surface mass balance (SMB) and the ice dynamics using a simplified energy balance model coupled to a vertically integrated shallow ice approximation 2D glacier flow model. The mass balance model is forced with temperature and precipitation measurements from a nearby weather station at Glomfjord. The SMB model is calibrated on individual stake measurements of winter and summer mass balance over the period 1990--2010 in the Engabreen catchment. The bed topography is reconstructed from iteratively matching modeled and observed surface elevation, and the reconstruction reproduces the observed large ice thickness east of the highest point of the ice cap of about 650 m well. We use the calibrated model to reconstruct the 20th century evolution of the Svartisen ice cap and its fate under the projected climate change in the 21st century. In addition, we explore the possibilities of calibrating the glacier model with only remotely sensed volume and velocity changes such that the model framework can be applied to glaciers for which no in-situ observations are available.