Updated cloud physics in a regional atmospheric climate model improves the modelled surface energy balance of Antarctica

作者：van Wessem J M^*; Reijmer C H; Lenaerts J T M; van de Berg W J; van den Broeke M R; van Meijgaard E

来源：Cryosphere, 2014, 8(1): 125-135.

DOI：10.5194/tc-8-125-2014

In this study the effects of changes in the physics package of the regional atmospheric climate model RACMO2 on the modelled surface energy balance, near-surface temperature and wind speed of Antarctica are presented. The physics package update primarily consists of an improved turbulent and radiative flux scheme and a revised cloud scheme that includes a parameterisation for ice cloud super-saturation. The ice cloud super-saturation has led to more moisture being transported onto the continent, resulting in more and optically thicker clouds and more downward long-wave radiation. Overall, the updated model better represents the surface energy balance, based on a comparison with > 750 months of data from nine automatic weather stations located in East Antarctica. Especially the representation of the turbulent sensible heat flux and net long-wave radiative flux has improved with a decrease in biases of up to 40%. As a result, modelled surface temperatures have increased and the bias, when compared to 10m snow temperatures from 64 ice-core observations, has decreased from -2.3K to -1.3 K. The weaker surface temperature inversion consequently improves the representation of the sensible heat flux, whereas wind speed biases remain unchanged. However, significant model biases remain, partly because RACMO2 at a resolution of 27 km is unable to resolve steep topography.

• 出版日期2014