1.11
One-dimensional energy fluxes of a snow cover in winter 1996/97 at the Schauinsland, Black-Forest (Germany)
PAPER WITHDRAWN
Stefan W. Vogel, University of California, Santa Cruze, CA; and C. Schneider
An investigation into the snow cover dynamic and the
one dimensional energy fluxes at a test site in the Black Forest was carried
out at the Schauinsland, Freiburg, in winter 1996/97. The time period of the
investigation was from 25th November 1996 until 5th March
1997. During this period the snow cover changes were observed and
meteorological data were sampled at an automatic weather station (AWS). The
meteorological data were used to calculate the energy balance. The atmospheric
energy balance of the snow surface (Q) is determined by the net radiation (R),
the latent heat flux (H) and the sensible heat flux (E). For calculation of the
snowmelt the soil heat flux (Hs) was added.
Q = R + H + E + Hs
Net radiation (R) and soil heat flux (Hs)
were measured directly. The turbulent heat fluxes were computed from wind
speed, humidity gradients and temperature gradients by differential bulk
approach. The modelled energy balance was used to compute snowmelt. This was
compared to the snowmelt as observed for each time period between two snow pit
measurements. Snow pit observations were carried out approximately every two to
three days.
Differences between computed and observed snowmelt can
be attributed to additional energy input from precipitation or to the retention
volume of the snow cover. Additional energy input from precipitation e.g.
caused snowmelt from 13th to 24th December 1996. During
this period, the difference between computed and measured snowmelt corresponds
to the energy surplus supplied by rain.
During two periods with considerable snow melt (6th
to 13th and 18th to 25th February)
overestimation of snowmelt during the initial phase of the melting period was
compensated by underestimation during the on-going of melting. The amount of
this mismatch corresponds to the retention volume of the snow cover. During
both periods the overall amount of the computed snowmelt matches the measured
snowmelt.
The extraordinary overestimation of calculated
snowmelt during the final melting period (18th until 25th
February) is due to low albedo of bare soil after the last snow patches had
melted away.
The total amount of calculated snowmelt of 253 mm
water equivalent corresponds very well to the total measured snow volume of
251 mm water equivalent. Although this model does not include snow pack
processes it returns reasonable results for seasonal snow melt and seasonal
energy balance estimates at the study site.
Session 1, Surface Layers
Tuesday, 8 August 2000, 8:30 AM-2:15 PM
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