The influence of the inclusion of soil freezing on simulations by a soil-vegetation-atmosphere transfer scheme

The interactions between the soil biosphere, and atmosphere (ISBA) land sur face parameterization scheme has been modified to include soil ice. The liq uid water equivalent volumetric ice content is modeled using two reservoirs within the soil: a thin surface layer that directly affects the surface en ergy balance, and a deep soil layer The freezing/drying, wetting/thawing an alogy is used, and a description of the modifications to the ISBA force-res tore scheme, in particular to the hydrological and thermal transfer coeffic ients, is presented. In addition, the ISBA surface/vegetation scheme is cou pled to a multilayer explicit diffusion soil heat and mass transfer model i n order to investigate the accuracy of the force-restore formalism soil fre ezing parameterization as compared with a higher-order scheme, An example of the influence of the inclusion of soil freezing in ISBA on pr edicted surface and soil temperatures and surface fluxes is examined using prescribed atmospheric forcing from a micrometeorological case study that i ncludes freeze-thaw cycles. Surface temperature prediction is improved in c omparison with the observed values, especially at night. primarily from the release of latent heat as the soil freezes. There is an improvement in the overall surface flux prediction, although for some specific periods there is increased error in the prediction of various components of the surface e nergy budget. Last, the simplified force-restore approach is found to produ ce surface Bur and temperature predictions consistent with the higher-resol ution model, on typical numerical weather prediction model timescales (on t he order of several days to two weeks) for this particular site.