Closing the mass budget of a tidewater glacier: The example of Kronebreen, Svalbard

Abstract

In this study, we combine remote sensing, in situ and model-derived datasets from 1966 to 2014 to calculate the mass-balance components of Kronebreen, a fast-flowing tidewater glacier in Svalbard. For the well-surveyed period 2009-2014, we are able to close the glacier mass budget within the prescribed errors. During these 5 years, the glacier geodetic mass balance was -0.69 ± 0.12 m w.e. a -1 , while the mass budget method led to a total mass balance of -0.92 ± 0.16 m w.e. a -1 , as a consequence of a strong frontal ablation (-0.78 ± 0.11 m w.e. a -1 ), and a slightly negative climatic mass balance (-0.14 ± 0.11 m w.e. a -1 ). The trend towards more negative climatic mass balance between 1966-1990 (+0.20 ± 0.05 m w.e. a -1 ) and 2009-2014 is not reflected in the geodetic mass balance trend. Therefore, we suspect a reduction in ice-discharge in the most recent period. Yet, these multidecadal changes in ice-discharge cannot be measured from the available observations and thus are only estimated with relatively large errors as a residual of the mass continuity equation. Our study presents the multidecadal evolution of the dynamics and mass balance of a tidewater glacier and illustrates the errors introduced by inferring one unmeasured mass-balance component from the others.