Climate of the Greenland ice sheet using a high-resolution climate model – Part 2: Near-surface climate and energy balance 1Institute for Marine and Atmospheric research Utrecht, Utrecht University, Utrecht, The Netherlands
01 Dec 2010
2Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede, The Netherlands
3Royal Netherlands Meteorological Institute, De Bilt, The Netherlands
Received: 29 Mar 2010 – Published in The Cryosphere Discuss.: 21 Apr 2010Abstract. The spatial variability of near-surface variables and surface energy balance
components over the Greenland ice sheet are presented, using the output of a
regional atmospheric climate model for the period 1958–2008. The model was
evaluated in Part 1 of this paper.
Revised: 15 Sep 2010 – Accepted: 27 Sep 2010 – Published: 01 Dec 2010
The near-surface temperature over the ice sheet is affected by surface
elevation, latitude, longitude, large-scale and small-scale advection,
occurrence of summer melt and mesoscale topographical features. The
atmospheric boundary layer is characterised by a strong temperature
inversion, due to continuous longwave cooling of the surface. In combination
with a gently sloping surface the radiative loss maintains a persistent
katabatic wind. This radiative heat loss is mainly balanced by turbulent
sensible heat transport towards the surface. In summer, the surface is near
radiative balance, resulting in lower wind speeds. Absorption of shortwave
radiation and a positive subsurface heat flux due to refreezing melt water
are heat sources for surface sublimation and melt.
The strongest temperature deficits (>13 °C) are found on the
northeastern slopes, where the strongest katabatic winds (>9 m s−1) and
lowest relative humidity (<65%) occur. Due to strong large scale winds,
clear sky (cloud cover <0.5) and a concave surface, a continuous supply of
cold dry air is generated, which enhances the katabatic forcing and
suppresses subsidence of potentially warmer free atmosphere air.
Citation: Ettema, J., van den Broeke, M. R., van Meijgaard, E., and van de Berg, W. J.: Climate of the Greenland ice sheet using a high-resolution climate model – Part 2: Near-surface climate and energy balance, The Cryosphere, 4, 529-544, doi:10.5194/tc-4-529-2010, 2010.