Quick start

After installing CryoGrid.jl, you can get started right away with a simple soil heat model. The Presets module (aliased CryoGrid.Presets) provides pre-specified model configurations that can be obtained with a single function call. It is also possible to modify the soil and initial temperature profiles via SoilLayerConfig; here SamoylovDefault is used.

Single layer heat conduction model with free water freeze curve and air temperature upper boundary condition:

using CryoGrid
using Plots

# load provided forcing data from Samoylov;
# The forcing file will be automatically downloaded to the input/ folder if not already present.
forcings = loadforcings(CryoGrid.Presets.Forcings.Samoylov_ERA_obs_fitted_1979_2014_spinup_extended_2044, :Tair => u"°C");
# get preset soil and initial temperature profile for Samoylov
soilprofile, tempprofile = CryoGrid.Presets.SamoylovDefault
initT = initializer(:T, tempprofile)
# choose grid with 5cm spacing
grid = CryoGrid.Presets.DefaultGrid_5cm
# basic 1-layer heat conduction model (defaults to free water freezing scheme)
tile = CryoGrid.Presets.SoilHeatTile(TemperatureBC(forcings.Tair), GeothermalHeatFlux(0.053u"W/m^2"), soilprofile, initT, grid=grid)
# define time span (1 year)
tspan = (DateTime(2010,11,30),DateTime(2011,11,30))
u0, du0 = initialcondition!(tile, tspan)
# CryoGrid front-end for ODEProblem
prob = CryoGridProblem(tile, u0, tspan, savevars=(:T,))
# solve discretized system, saving every 3 hours;
out = @time solve(prob, saveat=3*3600.0, progress=true) |> CryoGridOutput;
zs = [2,7,12,22,32,42,50,100,500]u"cm"
cg = Plots.cgrad(:copper,rev=true)
plot(out.T[Z(Near(zs))], color=cg[LinRange(0.0,1.0,length(zs))]', ylabel="Temperature", leg=false)


Alternatively, we can use a Dall'Amico freeze curve:

sfcc = SFCC(DallAmico(swrc=VanGenuchten(α=0.02, n=1.8))) # silt/clay-like freeze curve
tile2 = CryoGrid.Presets.SoilHeatTile(TemperatureBC(forcings.Tair), GeothermalHeatFlux(0.053u"W/m^2"), soilprofile, initT, grid=grid, freezecurve=sfcc)
u0, du0 = initialcondition!(tile2, tspan)
# CryoGrid front-end for ODEProblem
prob2 = CryoGridProblem(tile2, u0, tspan, savevars=(:T,))
out2 = @time solve(prob2, saveat=3*3600.0, progress=true) |> CryoGridOutput;
plot(out2.T[Z(Near(zs))], color=cg[LinRange(0.0,1.0,length(zs))]', ylabel="Temperature", leg=false)

Note that SoilHeatTile uses energy as the state variable by default. To use temperature as the state variable instead:

# :T is the variable name for temperature, :H represents enthalpy/energy.
# This is used in the specification of the HeatBalance process type.
# While this will work with any freeze curve, here we use Westermann (2011) as an example.
model = CryoGrid.Presets.SoilHeatTile(:T, TemperatureBC(forcings.Tair), soilprofile, freezecurve=SFCC(Westermann()))