GIPL(Geophysical Institute Permafrost Laboratory) is an implicit finite difference one-dimensional heat flow numerical model. The GIPL model uses the effect of snow layer and subsurface soil thermal properties to simulate ground temperatures and active layer thickness (ALT) by solving the 1D heat diffusion equation with phase change. The phase change associated with freezing and thawing process occurs within a range of temperatures below 0 degree centigrade, and is represented by the unfrozen water curve (Romanovsky and Osterkamp 2000). The model employs finite difference numerical scheme over a specified domain. The soil column is divided into several layers, each with distinct thermo-physical properties. The GIPL model has been successfully used to map permafrost dynamics in Alaska and validated using ground temperature measurements in shallow boreholes across Alaska (Nicolsky et al. 2009, Jafarov et al. 2012, Jafarov et al. 2013, Jafarov et al. 2014).
GIPL(Geophysical Institute Permafrost Laboratory) is an implicit finite difference one-dimensional heat flow numerical model.The model uses fine vertical resolution grid which preserves the latent-heat effects in the phase transition zone, even under conditions of rapid or abrupt changes in the temperature fields. It includes upper boundary condition (usually air temperature), constant geothermal heat flux at the lower boundary (typically from 500 to 1000 m) and initial temperature distribution with depth. The other inputs are precipitation, prescribed water content and thermal properties of the multilayered soil column. As an output the model produces temperature distributions at different depths, active layer thickness and calculates time of freeze up. The results include temperatures at different depths and active layer thickness, freeze-up days.
The GIPL model uses the effect of snow layer and subsurface soil thermal properties to simulate ground temperatures and active layer thickness (ALT) by solving the 1D heat diffusion equation with phase change. The phase change associated with freezing and thawing processes occurs within a range of temperatures below 0◦C, and is represented by the unfrozen water curve (Romanovsky and Osterkamp2000). The model employs a finite difference numerical scheme over a specified domain. The soil column is divided into several layers, each with distinct thermo-physical properties. Note that GIPL is driven by a prescribed soil moisture. The GIPL model has been successfully validated using ground temperature measurements in shallow boreholes across Alaska (Romanovsky and Osterkamp2000, Nicolsky et al2009).