Towards a TTOP ground temperature model for mountainous terrain in central‐eastern Norway

The lack of simple mountain permafrost distribution models taking snow depth and site‐specific factors into consideration led us to test the regional Canadian temperature at the top of the permafrost or at the bottom of the seasonally frozen layer (TTOP)‐model in mountain terrain in central‐eastern Norway. The TTOP‐model uses seasonal n‐factors (nt and nf) and air temperature to model the mean annual ground‐surface temperature (MAGST), and a ratio of thawed to frozen thermal conductivity to model the average TTOP. This study presents 28 and 36 values of nt and nf, respectively. The potential incoming solar radiation, derived in a Geographical Information System (GIS), was used to parameterise nt, and average snow depth was used to parameterise nf. Due to limited information on the subsurface component of the model, only MAGST was modelled. The model was run for the 1961–90 normal period, the Little Ice Age and the year 2050. The model was evaluated against existing model predictions based on bottom temperature of winter snow (BTS) and geophysical soundings. Finally, critical values of snow depth, potential incoming solar radiation and thermal conductivity ratio that constrain negative MAGST and thus permafrost were determined. Copyright © 2007 John Wiley & Sons, Ltd.