Articles | Volume 9, issue 1
Research article
27 Jan 2015
Research article |  | 27 Jan 2015

Mass changes in Arctic ice caps and glaciers: implications of regionalizing elevation changes

J. Nilsson, L. Sandberg Sørensen, V. R. Barletta, and R. Forsberg

Abstract. The mass balance of glaciers and ice caps is sensitive to changing climate conditions. The mass changes derived in this study are determined from elevation changes derived measured by the Ice, Cloud, and land Elevation Satellite (ICESat) for the time period 2003–2009. Four methods, based on interpolation and extrapolation, are used to regionalize these elevation changes to areas without satellite coverage. A constant density assumption is then applied to estimate the mass change by integrating over the entire glaciated region.

The main purpose of this study is to investigate the sensitivity of the regional mass balance of Arctic ice caps and glaciers to different regionalization schemes. The sensitivity analysis is based on studying the spread of mass changes and their associated errors, and the suitability of the different regionalization techniques is assessed through cross-validation.

The cross-validation results shows comparable accuracies for all regionalization methods, but the inferred mass change in individual regions, such as Svalbard and Iceland, can vary up to 4 Gt a−1, which exceeds the estimated errors by roughly 50% for these regions. This study further finds that this spread in mass balance is connected to the magnitude of the elevation change variability. This indicates that care should be taken when choosing a regionalization method, especially for areas which exhibit large variability in elevation change.

Short summary
The aim of this study is to determine and quantify the impact of different regionalization schemes on surface elevation changes, and how they affect the estimated spread in mass balance of Arctic ice caps and glaciers. The study found that the choice of regionalization has an important effect in regions with maritime climate and high variability in elevation change. In these areas the spread in mass balance was in many cases larger than the estimated errors of the individual methods.