Greenland Ice Sheet Surface Mass-balance Modeling in a 131-year Perspective, 1950-2080

Download or read book Greenland Ice Sheet Surface Mass-balance Modeling in a 131-year Perspective, 1950-2080 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluctuations in the Greenland Ice Sheet (GrIS) surface mass-balance (SMB) and freshwater influx to the surrounding oceans closely follow climate fluctuations and are of considerable importance to the global eustatic sea level rise. SnowModel, a state-of-the-art snow-evolution modeling system, was used to simulate variations in the GrIS melt extent, surface water balance components, changes in SMB, and freshwater influx to the ocean. The simulations are based on the IPCC scenario AlB modeled by the HIRHAM4 RCM (using boundary conditions from ECHAM5 AOGCM) from 1950 through 2080. In-situ meteorological station (GC-Net and WMO DMI) observations from inside and outside the GrIS were used to validate and correct RCM output data before it was used as input for SnowModel. Satellite observations and independent SMB studies were used to validate the SnowModel output and confirm the model's robustness. We simulated a ≈90% increase in end-of-summer surface melt extent (0.483 x 106 km2) from 1950 to 2080, and a melt index (above 2,000-m elevation) increase of 138% (1.96 x 106 km2 x days). The greatest difference in melt extent occured in the southern part of the GrIS, and the greatest changes in the number of melt days was seen in the eastern part of the GrIS (≈50-70%) and was lowest in the west (≈20-30%). The rate of SMB loss, largely tied to changes in ablation processes, lead to an enhanced average loss of 331 km3 from 1950 to 2080, an average 5MB level of -99 km3 for the period 2070-2080. GrIS surface freshwater runoff yielded an eustatic rise in sea level from 0.8 ± 0.1 (1950-1959) to 1.9 ± 0.1 mm (2070-2080) sea level equivalent (SLE) y−1. The accumulated GrIS freshwater runoff contribution from surface melting equaled 160 mm SLE from 1950 through 2080.