Climate of the Greenland ice sheet using a high-resolution climate model – Part 1: Evaluation

A simulation of 51 years (1957–2008) has been performed over Greenland using the regional atmospheric climate model RACMO2 at a horizontal grid spacing of 11 km forced by ECMWF analysis products. To better represent processes affecting ice sheet surface mass balance, such as melt water refreezing and penetration, an additional snow/ice surface module has been developed and implemented into the surface parameterisation of RACMO2v1. The temporal evolution and climatology of the model is evaluated with in situ coastal and ice sheet atmospheric measurements of near-surface variables and surface energy balance components. The bias for the near-surface air temperature (0.9 °C), specific humidity (0.1 g kg 1), wind speed (0.3 m s 1) as well as for radiative (2.5 W m 2 for net radiation) and turbulent heat fluxes shows that the model is in good accordance with available observations. The modeled surface energy budget underestimates the downward longwave radiation and overestimates the sensible heat flux. Due to their compensating effect, the averaged 2 m temperature bias is less than 0.9°C. The katabatic wind circulation is well captured by the model.