Surface water vapor exchanges on the Greenland ice sheet derived from automated weather station data

Greenland Climate Network (GC-Net) meteorological observations are used to estimate surface water vapor exchanges at Greenland ice sheet sites and for the ice sheet as a whole for the period of mid 1995 to mid 2000. Water vapor fluxes were derived using aerodynamic profile methods and validated with eddy correlation and evaporation pan measurements. A net water vapor flux to the atmosphere predominates in summer below 2000 m elevation sites. The net water vapor flux is -87 +/- 30 mm y-1 water equivalence in the Jakobshavn ablation region at 962 m elevation and -74 +/- 26 mm y-1 at equilibrium line altitude (1150 m) 17 km up-glacier. Net deposition is observed at an undulation trough site, whereas at the adjacent crest site, 6 km away, net water vapor loss is observed. At high elevation sites, the annual water vapor flux is towards the surface, approximately +15 mm y-1. Comparison of monthly values with output from the NCAR Mesoscale Model (MM5) indicate that the month to month variability is well reproduced; yet the magnitude is underestimated by as much as 150%.; Based on a trend surface regression of the temperature lapse rate along the slope, elevation, and latitude, a Greenland ice sheet annual net total water vapor flux of -7.34 +/- 4.4 x 1013 kg y-1 is derived. This estimates is similar to the result of -6.18 x 1013 kg y-1 [ Ohmura et al., 1999] based on atmospheric modeling. The precipitation loss is estimated to be 14%, given an ice sheet accumulation estimate of 5.90 x 1014 kg y-1 by Ohmura et al. [1999].; Annual blowing snow sublimation is estimated using a bulk snow transport formulation and a conceptual model of maximum blowing snow transport distance. The actual blowing snow transport is estimated using potential transport calculations derived from wind speed records and a snow availability factor derived from air temperature and surface height measurements. Blowing snow sublimation rates are estimated to be as great as 500 mm y-1 at sites with strongest winds.