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Very high-resolution regional climate simulations over Greenland with the
HIRHAM model
Philippe Lucas-Picher, Jens H. Christensen, Martin Stendel and Gudfinna Aðalgeirsdóttir
Danish Meteorological Institute, Lyngbyvej 100, DK-2100 Copenhagen Ø, Denmark; plp@dmi.dk
1. Introduction
Recent progress in available computer power allows
regional climate models to run at an increasingly higher
horizontal resolution, down to the order of a few kilometers.
At this resolution, climate simulations over Greenland
become more realistic, in part due to the enhanced
description of the rugged topography of the ice cap that
affects the atmospheric circulation. Climate simulations at
such resolution are very interesting for permafrost models,
which require detail values of temperature and precipitation
on the margin of the Greenland glacier. Moreover, the
description of climate variable at high resolution is also very
useful for glacier model to compute the surface mass
balance of the glacier. Thus, a RCM simulation at 5 km
simulation is presented. At the same time, it is also
interesting to assess the added value of high-resolution
simulations over Greenland, by comparing regional climate
simulations with different resolutions.
2. Methodology
Three regional climate model simulations are performed
with the HIRHAM model using three different resolutions
(5, 25 and 75 km) for a similar domain covering the entire
Greenland. The simulations cover the period 1989-2005
with 31 vertical levels and use the ERA-Interim as lateral
boundary conditions. The analysis focuses on the validation
of these simulations by using observation records from
ground stations and on the emerging climate details that
accompany increasing resolution.
3. Preliminary results
This work is in progress. When writing the abstract, the
simulations are ongoing in the supercomputer. A
preliminary simulation was executed to get a first idea of the
performance of the HIRHAM model at 5 km resolution. The
simulation covers the same period (1989-2005) and
resolution (5 km) with 19 levels for a domain covering south
of Greenland. The domain contains 386 x 386 grid cells. At
first sight, the simulation makes sense when comparing with
observation data as CRU (not shown). However, a deeper
analysis with observation records from ground stations is
required to validate the simulation because spatial
observation database is only available at coarse resolution
and is produced from ground stations, which are sparsely
distributed over Greenland. Figure 1 shows a zoom of the
topography and of the 1989-2005 precipitation climatology
in summer (JJA) in the south of the domain. We can see in
Fig. 1b the details of the precipitation pattern, which is in
agreement with the topography in Fig. 1a. Such details for
the precipitation pattern are promising to feed permafrost
and glacier models.
Figure 1. Zoom of the south of the domain for a)
the topography in meters and for b) the 1989-2005
precipitation climatology in summer (June-July-
August) in mm/day.
4. Coming next…
A deeper validation of the simulations will be done using
available observation records from ground stations. We
will particularly pay attention to the quality of the
precipitation, which is one of the controlling fields for a
good simulation of the surface mass balance of the glacier
and permafrost conditions surrounding the ice sheet.
m
mm/day