Figures 7.2 and 7.3 compare the results of FASST with those of SNTHERM against the
measured values for two sites in Colorado. SNTHERM (Jordan 1991a) is considered the
most physically based snow model. The Buffalo Pass site is characterized by an
accumulation period followed by an ablation period that begins on approximately day
130. Both models accurately transition between the two seasons. FASST underestimates
the meltout date by three days while SNTHERM overestimates it by three days. Within
five days is considered accurate (Holcombe et al. 2004). The absolute (average of model
measured) and relative (average of [modelmeasured]/measured) errors for both models
are 8% and 3%, respectively.
The snowpack at the Illinois River site, Figure 7.3, is characterized as thin, ephemeral,
and windblown. This is a more difficult modeling scenario. Despite this, both models do
well. The absolute error is < 1% while the relative error is 2 % for SNTHERM and 11%
for FASST.
7.6 References
Albert, M., and G. Krajeski (1998) Fast, Physically Based Point Snow Melt Model for
use in Distributed Applications. Hydrological Process, V. 12, p. 18091824.
Anderson, E.A. (1973) National Weather Service River Forecast System Snow
Accumulation and Ablation Model. NOAA Technical Mem. NWS 17, Bethesda, MD.
Bader H., R. Haefeli, E. Bucher, J. Neher, O. Eckel, and C. Thams (1954) Snow and
its Metamorphism, SIPRE Translation 14. U.S. Army Corps of Engineers Snow, Ice and
Permafrost Organization, Hanover, NH.
Bender, J.A. (1957) Air Permeability of Snow. U.S. Army Corps of Engineers Snow, Ice
and Permafrost Organization, Hanover, NH, SIPRE Research Report 37.
Brun, E. (1989) An Energy and Mass Model of Snow Cover Suitable for Operational
Avalanche Forecasting. Journal of Glaciology, V. 35, No. 121, p. 333342.
Carslaw, H.S., and J.C. Jaeger (1959) Conduction of Heat in Solids, Oxford: Clarendon
Press.
Colbeck, S.C. (1972) A Theory of Water Percolation in Snow. Journal of Glaciology, V.
11, No. 63, p. 369385.
Holcombe, J.D., K. Elder, S. Frankenstein, S. Fassnacht and R.E. Davis (2004)
Seasonal Simulations of Snow Depth and Soil Moisture at Two Different NASA CLPX
Sites. Hydrological Processes, submitted.
Jordan, R. (1991a) A One-Dimensional Temperature Model for a Snow Cover:
Technical Documentation for SNTHERM.89. U.S. Army Cold Regions Research and
Engineering Laboratory, Special Report 91-16.
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