Martin Hagman, MISU


Title: High-resolution simulations of the night-time stable boundary layer over snow

The stable boundary layer (SBL) has appeared problematic both to understand and to simulate in atmospheric models. In this study the nocturnal SBL over snow was studied via 1-D clear-sky simulations at 67 degrees north in Sodankylä in northern Finland. Three wind regimes could be identified and the properties of these are described. The snow surface was coldest after a calm night and warmer at windy sunrises, whereas the coldest temperatures were obtained during weak winds, provided that the model's stability functions were of "short tails" type.

When the model’s multilayer snow scheme was replaced by a coarse scheme, the nocturnal Ts and T2m stayed too warm. The use of old snow properties instead of typical snow produced relatively warm nocturnal temperatures whereas fresh snow led to quite cold temperatures. These aspects may have relevance to the SBL warm
biases of large-scale models.


Thursday May 23, 14:15


Rossbysalen C609, Arrhenius laboratory, Svante Arrhenius väg 16C, 6th floor