The Cryosphere Discussions
www.the-cryosphere-discuss.net
1994-0432
1994-0440
3
1
2009
10.5194/tcd-3-277-2009
http://www.the-cryosphere-discuss.net/3/277/2009/
http://www.the-cryosphere-discuss.net/3/277/2009/tcd-3-277-2009.html
http://www.the-cryosphere-discuss.net/3/277/2009/tcd-3-277-2009.pdf
277
306
2009-04-08
The role of radiation penetration in the energy budget of the snowpack at Summit, Greenland
P. Kuipers Munneke
p.kuipersmunneke@uu.nl
M. R. van den Broeke
C. H. Reijmer
M. M. Helsen
W. Boot
M. Schneebeli
K. Steffen
Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, The Netherlands
WSL Institute for Snow and Avalanche Research, Davos, Switzerland
Cooperative Institute for Research in Environmental Sciences, University of Colorado, USA
Measurements of the summer surface energy balance at Summit, Greenland, are
presented (8 June–20 July 2007). These measurements serve as input to an
energy balance model that searches for a surface temperature for which
closure of all energy terms is achieved. A good agreement between observed
and modeled surface temperatures was found, with an average difference of
0.45°C and an RMSE of 0.85°C. It turns out that penetration
of shortwave radiation into the snowpack plays a small but important role in
correctly simulating snow temperatures. After 42 days, snow temperatures in
the first meter are 3.6–4.0°C higher compared to a model simulation
without radiation penetration. Sensitivity experiments show that these
results cannot be reproduced by tuning the heat conduction process alone, by
varying snow density or snow diffusivity. We compared the two-stream
radiation penetration calculations with a sophisticated radiative transfer
model and discuss the differences. The average diurnal cycle shows that net
shortwave radiation is the largest energy source (+61 W m<sup>−2</sup> on
average), net longwave radiation the largest energy sink
(−42 W m<sup>−2</sup>). On average, subsurface heat flux, sensible and latent
heat fluxes are the remaining, small heat sinks (−5, −5 and
−7 W m<sup>−2</sup>, respectively), although these are more important on a
subdaily timescale.
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