Greenland ice sheet surface mass balance
1991–2000: Application of Polar MM5 mesoscale model and in situ data
Jason
E. Box1,2, David H. Bromwich1,2,
and Le-Sheng Bai1
1 - Polar
Meteorology Group, Byrd Polar Research Center, Ohio State University,
Columbus, Ohio, USA
2 - Department of Geography, Atmospheric Sciences Program, Ohio State
University, Columbus, Ohio, USA
Abstract The Polar Pennsylvania State
University–National Center for Atmospheric Research Fifth-Generation
Mesoscale Model (Polar MM5) regional climate model was run over the
North Atlantic region for 1991–2000. We analyze 24-km output over the
Greenland ice sheet to evaluate spatial and temporal variability of the
surface mass balance and its subcomponents. The model output is
compared with 3 years of automatic weather station (AWS) data from 17
sites to identify biases. Using the in situ data, we derive simple
corrections for biases in melt energy and in water vapor fluxes from
the surface and from blowing snow. The simulated accumulation rate is
in agreement with AWS and snow pit observations. Estimates for runoff
and the surface mass balance distribution over the ice sheet are
produced using modeled melt volume and a meltwater retention scheme.
From the decade investigated, the magnitude of interannual variability
in surface mass balance components is tentatively established. The
largest variability is concentrated along the ice sheet margin, where
both accumulation and ablation rates are largest. The simulated
interannual fluctuations suggest a large absolute variability,
±187 cubic km per yr for total ice sheet surface mass balance.
Variability in simulated equilibrium line altitude is suggestive of a
dominance of thermal variability in the south with increasing
importance of accumulation variability with increasing latitude.
Empirical functions for the sensitivity of surface mass balance to
temperature and precipitation anomalies are presented. The precise
locations and regions of maximum and minimum surface energy and mass
fluxes are suggested. Using an estimate for iceberg discharge and
bottom melting, the total ice sheet mass balance is estimated be -78
cubic km per yr, producing 2.2 mm of eustatic sea level rise over the
1991–2000 decade and contributing 15% to the observed (1.5 mm/yr)
global sea level rise. The more negative mass balance is attributed to
including blowing snow sublimation loss and to regional warming in the
1990s.
Citation: Box, J. E., D. H. Bromwich, and L.-S. Bai (2004), Greenland
ice sheet surface mass balance 1991–2000: Application of Polar MM5
mesoscale model and in situ data, J. Geophys. Res., 109, D16105,
doi:10.1029/2003JD004451. PDF
Received 15 December 2003; revised 30 April 2004; accepted 12 May 2004;
published 26 August 2004.
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