| Summary: | - The mass balance of M & yacute;rdalsjiikull, the fourth largest Icelandic ice cap (520 km2 in 2019), has received less attention so far than the mass balance of the three largest ice caps, Vatnajiikull, Hofsjiikull and Langjiikull. Here, we used digital elevation models (DEMs) derived from the untapped SPOT5 archive (2003-2014), lidar data (2010), Pl & eacute;iades imagery (2014-2021), aerial photographs from 1999 and the ArcticDEM dataset (2010-2018) to estimate the mass balance of M & yacute;rdalsjiikull. A pre-processing of the DEMs was first performed: co-registration, filtering and void interpolation. Then, applying a Gaussian Process (GP) regression, a spatially and temporally continuous elevation dataset was created, in 15x15 m resolution and 30-day increments over the time span 1999 to 2021. Volume and mass changes based on the GP-interpolated elevation dataset were computed and analysed in 5- to 6-year intervals between 1999 and 2021. An average mass balance of -1.23 +/- 0.10 m w.e. a-1 was estimated for this time period, with a trend towards a less negative mass balance from -1.83 +/- 0.13 m w.e. a-1 (1999-2005) to -0.41 +/- 0.03 m w.e. a-1 (2016-2021). An analysis of three climatically different catchments of M & yacute;rdalsjiikull showed a significant spatial variability in the estimated mass balance but a similar temporal variation.
|
|---|