Evaluating a regional climate model simulation of Greenland ice sheet snow and firn density for improved surface mass balance estimates

• Published in: Geophysical Research Letters
• Main Authors: Alexander, P., Tedesco, M., Koening, L., Fettweis, Xavier
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Greenland; Ice Sheet
• Online Access: https://orbi.uliege.be/handle/2268/240310; https://orbi.uliege.be/bitstream/2268/240310/1/Alexander_et_al-2019-Geophysical_Research_Letters.pdf; https://doi.org/10.1029/2019GL084101

peer reviewed Modeling vertical profiles of snow and firn density near the surface of the Greenland ice sheet (GrIS) is key to estimating GrIS mass balance, and by extension, global sea level change. To understand sources of error in simulated GrIS density, we compare GrIS density profiles from a leading regional climate model with coincident in situ measurements. We identify key contributors to model density and mass balance biases, including underestimated simulated fresh snow density (which leads to underestimation of density in the top 1 m of snow by ~10%). In areas undergoing frequent melting, positive density biases (of 7% in the top 1 m, and 10% between 1 and 10 m) are likely associated with errors in representing meltwater production, retention and refreezing. The results highlight the importance of accurately capturing fresh snow density and meltwater processes in models used to estimate GrIS mass balance change.