We have conducted tests of the Canadian Land Surface Scheme (CLASS V2.5) for
Arctic tundra applications. Our tests emphasize sensitivities to initial
conditions, external forcings and internal parameters, and focus on the
Alaskan North Slope during the summer of 1992. Observational data from the
National Science foundation (NSF), Arctic Systems Science (ARCSS),
Land/Atmosphere/Ice Interactions (LAII) Flux Study is available to serve as
forcing and validation for our simulations.
Comparisons of the runs show strong sensitivities to the composition and
depth of the soil layers, and we find that a minimum total soil depth of 5.0
m is needed to maintain permafrost. The response of the soil to diurnal
variations in forcing is strong, while sensitivities to other internal
parameters, as well as to precipitation, were relatively small. Some
sensitivity to air temperatures and radiative fluxes, particularly the
incoming shortwave flux, was also present. Significant sensitivity to the
specification of the initial water and ice contents of the soil was found,
while the sensitivity to initial soil temperature was somewhat less.