A long-term dataset of climatic mass balance, snow conditions, and runoff in Svalbard (1957–2018)
<p>The climate in Svalbard is undergoing amplified change compared to the global mean. This has major implications for runoff from glaciers and seasonal snow on land. We use a coupled energy balance–subsurface model, forced with downscaled regional climate model fields, and apply it to both gl...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-09-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/13/2259/2019/tc-13-2259-2019.pdf |
| Summary: | <p>The climate in Svalbard is undergoing amplified change compared to the global mean. This has major implications for runoff from glaciers and seasonal snow on land. We use a coupled energy balance–subsurface model, forced with downscaled regional climate model fields, and apply it to both glacier-covered and land areas in Svalbard. This generates a long-term (1957–2018) distributed dataset of climatic mass balance (CMB) for the glaciers, snow conditions, and runoff with a <span class="inline-formula">1 km×1 km</span> spatial and 3-hourly temporal resolution. Observational data including stake measurements, automatic weather station data, and subsurface data across Svalbard are used for model calibration and validation. We find a weakly positive mean net CMB (<span class="inline-formula">+0.09</span> m w.e. a<span class="inline-formula"><sup>−1</sup></span>) over the simulation period, which only fractionally compensates for mass loss through calving. Pronounced warming and a small precipitation increase lead to a spatial-mean negative net CMB trend (<span class="inline-formula">−0.06</span> m w.e. a<span class="inline-formula"><sup>−1</sup></span> decade<span class="inline-formula"><sup>−1</sup></span>), and an increase in the equilibrium line altitude (ELA) by 17 m decade<span class="inline-formula"><sup>−1</sup></span>, with the largest changes in southern and central Svalbard. The retreating ELA in turn causes firn air volume to decrease by 4 % decade<span class="inline-formula"><sup>−1</sup></span>, which in combination with winter warming induces a substantial reduction of refreezing in both glacier-covered and land areas (average <span class="inline-formula">−4</span> % decade<span class="inline-formula"><sup>−1</sup></span>). A combination of increased melt and reduced refreezing causes glacier runoff (average 34.3 Gt a<span class="inline-formula"><sup>−1</sup></span>) to double over the simulation period, while discharge from land (average 10.6 Gt a<span class="inline-formula"><sup>−1</sup></span>) remains nearly unchanged. As a result, the relative contribution of land runoff to total runoff drops from 30 % to 20 % during 1957–2018. Seasonal snow on land and in glacier ablation zones is found to arrive later in autumn (<span class="inline-formula">+1.4</span> d decade<span class="inline-formula"><sup>−1</sup></span>), while no significant changes occurred on the date of snow disappearance in spring–summer. Altogether, the output of the simulation provides an extensive dataset that may be of use in a wide range of applications ranging from runoff modelling to ecosystem studies.</p> |
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| ISSN: | 1994-0416 1994-0424 |