Inhaltszusammenfassung

The interactions between atmosphere and snowpack are important for modelling the boundary layer (BL) over snow surfaces. To study these interactions, the mesoscale local model (LM) of the German Meteorological Service is applied for simulations over Greenland at a horizontal resolution of about 14 km and a high vertical resolution of the BL. Since usage of the snow/soil model as implemented in LM leads to unrealistic representation of the snowpack, adjustments of the representation of snow pr...The interactions between atmosphere and snowpack are important for modelling the boundary layer (BL) over snow surfaces. To study these interactions, the mesoscale local model (LM) of the German Meteorological Service is applied for simulations over Greenland at a horizontal resolution of about 14 km and a high vertical resolution of the BL. Since usage of the snow/soil model as implemented in LM leads to unrealistic representation of the snowpack, adjustments of the representation of snow properties in LM have been done for the simulation over the Greenland ice sheet. Simulations using LM are performed for a ten-day period in July 2002, during which a field experiment took place at station Summit. To validate the model LM, the model results are compared to these measurements. The comparison shows some deficies for the near-surface values of temperature as well as turbulence quantities. The turbulence parameterisation in the LM has deficies for very stable stratification. Therefore, a local mixing length approach and the parameterisation of a scalar roughness length over ice and snow are implemented in the LM and their influence on the model performance is tested. These sensitivity studies show an improvement of turbulent kinetic energy and heat flux with usage of scalar roughness length as well as local mixing length approach. For a first estimation of the influence of snow drift on the snow accumulation, the LM results are used to drive the onedimensional snow model SNOWPACK in an off-line mode. SNOWPACK has a much better representation of snow than the LM snow/soil model and allows for simulating snow microphysical properties. While over large parts of the plateau area of the ice sheet the influence of snow drift on the snow accumulation is much smaller than the evaporation/sublimation, snow drift influence is of at least the same magnitude in regions of the ice sheet margins, associated with large divergence/convergence.» weiterlesen» einklappen

Autoren

Klassifikation

DDC Sachgruppe:
Naturwissenschaften