Publication Date:
2019-07-16
Description:
Some primary physical relationships related to the surface climate and atmospheric
boundary layer were examined over East Antarctica and evaluated in the regional
climate model HIRHAM for 2005–2008. For stable conditions, the observation-derived
relationship between wind-scaled sensible heat flux and air-surface temperature difference
distinctively differs between different surface flux parameterizations. Some of them
decrease the heat transfer coefficient CH for strongly stable conditions, while others,
such as the Louis scheme, do not. However, HIRHAM’s application of the Louis
parameterization produces small CH for strongly stable conditions similar to observations
and other schemes, likely because a surface roughness much larger than observed is used
and the bulk Richardson number differs. For Zhongshan, the observed radiation-cloud,
temperature-cloud, and temperature-wind relationships are reproduced in the model,
though quantitative differences are evident. An observed longwave warming effect of
clouds is larger in the model, while the reduction of downwelling shortwave radiation
by clouds is twice as large in the model. The model partially reproduces an observed weak
wind regime associated with atmospheric decoupling, but fails to reproduce increasing
temperatures with increasing winds. The quantitative differences in the radiation-cloud
relationship suggest that errors in cloud characteristics produce a significant deficiency
in downwelling net radiation for clear and cloudy conditions. This deficiency is the likely
cause of HIRHAM’s strong cold bias in the surface temperature and positive bias
in near-surface stability. The sensible heat flux analyses and a sensitivity test suggest
that errors in the sensible heat flux relationship are not the primary cause.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
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