Modeling the Glacier Mass Balance of Entire Svalbard - Challenges and Solutions

Abstract:

The Arctic archipelago of Svalbard is covered by very different types of glaciers reaching from large, flat and evenly formed ice caps to small, steep and narrow valley glaciers. Due to this high level of complexity and variability any glacier mass balance modeling is especially challenging. On such a regional-scales, it requires spatially distributed input data that reliably reproduce the variability of climate elements across the different terrain situations.

Modeling of glacier mass balance under such circumstances is increasingly based on output from regional climate models. However, the limited accuracy and spatial resolution of accordingly derived meteorological input often poses limitations when looking on subregional or local scales. Moreover, such meteorological input is still rarely available for larger regions and longer time periods.

This contribution presents and compares two very different studies. First, an evaluation is shown that analyses to which extent it is possible to derive reliable region-wide glacier mass balances for Svalbard on the basis of only coarse resolution (10 km) regional climate model output. A basic, index-based model with predefined parameters is used for mass-balance calculations in this case. All necessary calibrations and adjustments are done exclusively on the side of model forcing, i.e. the air temperature and precipitation fields of the regional climate model. Second, the contribution presents first results of an archipelago-wide energy balance modeling effort that is forced by 500 m resolution data of the recently developed high-resolution surface climatology HiRSvaC500. This dataset is especially designed to be applied in glacier mass balance modeling across Svalbard.

In situ reference for both modeling studies is provided by several hundred point mass balance measurements. This contribution shows and explains differences between the results of the two modeling studies. It outlines challenges and solutions during mass balance model calibrations and applications. And, in addition, it especially deals with the influences of the different, regionally varying accuracies of the applied modeling approaches and their impact on the reliability of Svalbard-wide glacier mass balance numbers.