Inhaltszusammenfassung

Surface winds and energy fluxes from measurements of stations on the ice sheet and in the tundra area near Kangerlussuaq, West Greenland, are presented for the period of the experiment KABEG (Katabatic wind and boundary layer front experiment around Greenland) in April/May 1997. For almost all days a nighttime development of the katabatic wind is found over the ice sheet causing a peak to peak amplitude of up to 5 m/s for the wind speed anomaly. A variational approach is used to compute turbu...Surface winds and energy fluxes from measurements of stations on the ice sheet and in the tundra area near Kangerlussuaq, West Greenland, are presented for the period of the experiment KABEG (Katabatic wind and boundary layer front experiment around Greenland) in April/May 1997. For almost all days a nighttime development of the katabatic wind is found over the ice sheet causing a peak to peak amplitude of up to 5 m/s for the wind speed anomaly. A variational approach is used to compute turbulent fluxes from profiles in the surface layer over the ice sheet and over the tundra area. The fluxes over the tundra area are validated using direct eddy-correlation flux measurements. Profile-derived sensible heat fluxes show the tendency to overestimate the absolute flux values for stable conditions over the tundra area. Nighttime conditions over the tundra are also found to be associated with intermittent turbulence and instationarity. In contrast, katabatic wind conditions over the ice sheet are associated with continuous turbulence and quasi-stationary profiles. The energy loss by the net radiation over the ice sheet is compensated to a large extent by the turbulent flux of sensible heat during strong wind conditions. Mean roughness lengths for neutral conditions show values of 2.3 cm and 1.1x10-4 m for the vegetated tundra area and the ice surface, respectively.» weiterlesen» einklappen

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Klassifikation

DDC Sachgruppe:
Naturwissenschaften