Reanalysis Surface Mass Balance of the Greenland Ice Sheet along K-transect

Abstract:

The Greenland ice sheet (GrIS) has been the focus of climate studies due to its considerable impact on sea level rise. Accurate estimates of surface mass fluxes would contribute to understanding the cause of its recent changes and would help to better estimate the future contribution of the GrIS to sea level rise. In situ measurement provides direct estimates of the SMB, but are inherently limited by their spatial extent and representativeness. Physically based regional climate models (RCMs) are critical for understanding GrIS physical processes. However, their results are highly uncertain. Remote sensing (RS) contain valuable information but the links between RS data and the SMB terms are most often indirect and implicit. Given the lack of in situ information, imperfect models, and under-utilized RS data it is critical to merge the available data in a systematic way to better characterize the spatial and temporal variation of the GrIS SMB.

This work proposes a data assimilation framework that yields SMB estimates that benefit from a state-of-the-art snow/ice model (Crocus) and an albedo product. Comparison of our results against in-situ SMB measurements from the Kangerlussuaq transect shows that assimilation of the albedo product reduces the root mean square error (RMSE) of the posterior estimates of SMB by 51% and reduces bias by 95%.