Exploring the parameters of a simple model of the permafrost-climate relationship

The parameters of the TTOP model of the permafrost - climate relationship are examined, primarily through the use of numerical thermal modelling. The TTOP model is a simple analytical model that predicts the mean annual temperature at the top of permafrost, incorporating freezing and thawing air temperature indices (seasonal degree-days), transfer functions ("n factors") to estimate freezing and thawing ground surface temperature indices, and the ratio of frozen and thawed soil thermal conductivity.; Results from thermal conductivity models for saturated and unsaturated mineral and organic soils show that the soil thermal conductivity ratio can be reliably estimated from soil moisture content. Numerical analysis shows that the effect of unfrozen water on the ratio can be accommodated using a temperature-based parameterization. Other numerical studies demonstrate the effect of temperature sensor burial on freezing and thawing index values.; From numerical experiments, the relationship between MAAT and TTOP is robust in the presence of climate variability. Stationary inter-annual variability produces an error in the TTOP model for individual years that is greatest near TTOP = 0°C, although this error is small in multi-year averages. Larger errors in the TTOP model occur in the presence of a warming trend where permafrost degradation is initiated, due to the effect of latent heat as a talik develops. Other than this however, the TTOP model appears to be reasonably accurate under transient conditions.; Numerical study of the effect of snow cover on the ground surface temperature demonstrates the importance of active layer freezeback on the freezing n factor, as well as the importance of the mean annual temperature at the base of the active layer. Timing of snow cover initiation and the seasonal pattern of snow accumulation are also important. From these results, a model is developed to predict permafrost distribution, based on the thermal properties of the ground, and the thermal resistance of the snow cover. This model is used to map permafrost using Canadian climate data.