Master Thesis Defense by Carl Magnus Lotz Rosenberg

Title: Linking Greenland mass loss with NorthAtlantic sea surface temperatures and atmospheric circulation.

Abstract:
This thesis investigates if HIRHAM5 is able to produce reliable values for surface mass balance, and if these can be used to find a connection between melting of the Greenland Ice Sheet and sea surface temperature anomalies in the North Atlantic Region. The GRACE and GRACE-FO project has now been running for more than 20 years. This thesis uses the data about the mass loss of the Greenland Ice Sheet collected through this project, to verify the ability of the HIRHAM5 regional climate model to provide reliable data for the surface mass balanceof the Greenland Ice Sheet. By using data from GRACE and HIRHAM5 to make an estimate for calving which is then compared to discharge data from PROMICE, the two show the same long term trends in calving, indicating that the SMB output from HIRHAM5 is reliable.
GRACE data is then used as a control sample for calibrating a mass balance estimate going back to 1986, showing that the average mass loss of the Greenland Ice Sheet between 1986 and 2002 is 75 Gt per year, which might not be as balanced as expected. The same method could be used as a way to bridge the gap in measurements between the GRACE and GRACE-FO missions. Finally, HIRHAM5 data is then used in order to investigate a connection between melting of the Greenland Ice Sheet and sea surface temperature anomalies in the North Atlantic Ocean between Greenland and Northern Europe. This shows a correlation between the total melting during a year and the SST anomalies in the summer months of the same year, and the same months two years later.

Supervisor: Jens Hesselbjerg Christensen
Censor: Peter Aakjær