Deliverable 6.20 Observing systems for sea level in the Arctic

• Main Authors: Ludwigsen, Carsten Bjerre, Andersen, Ole Baltazar
• Format: Report
• Language: English
• Published: 2021
• Subjects: Arctic; INTAROS; Ocean Observing Systems; Sea Level; Satellite Altimetry; In Situ Data; Arctic Ocean; Climate change; Sea ice
• Online Access: https://zenodo.org/record/7180352; https://doi.org/10.5281/zenodo.7180352

The Arctic Ocean is at the frontier of the fast-changing climate in the northern latitudes and sea level trends is a bulk measure of ongoing processes related climate change. Observations of sea level in the Arctic Ocean are nonetheless difficult to validate with independent measurements and is globally the region where the sea level change is most uncertain. By using specialized methods for observing sea level with satellite altimetry over sea ice regions in the Arctic, we are able to construct an altimetric sea level record that is in good agreement with the sea level observed by tide gauges. However, long-term changes of tide-gauges are influenced by vertical land motion (VLM) caused by past and present changes of ice. A novel model of the elastic rebound from present changes of Arctic ice has been applied to create a VLM-model that agrees well with GNSS. Sea level change from altimetry and VLM-corrected tide gauges are compared to a reconstructed sea level estimate, derived from the sea level fingerprints of present-day mass changes and steric sea level change derived from available arctic T/S-profiles. The comparison shows that the freshwater change is dominating the Arctic sea level change. Several recommendations have been outlined, to improve future analysis and observations of Arctic Ocean sea level. The most important is the lack of in-situ data in several regions of the Arctic Ocean that are necessary to validate the observations from remote sensing.