6. Initial conditions file
Makes an initial conditions file with basic assumptions. The initial conditions or state file contains a number of modeling options. The state file is an .nc file with dimensions nSoil, nSnow, midSoil, midToto, ifcToto and scalarv. See: https://summa.readthedocs.io/en/latest/input_output/SUMMA_input/#initial-conditions-restart-or-state-file
State parameters are set at hard-coded values as follows:
Parameter |
Value |
Units |
Description |
|---|---|---|---|
dt_init |
taken from control file |
s |
Time step size of forcing data |
nSoil |
8 |
- |
Number of soil layers |
nSnow |
0 |
- |
Number of currently active snow layers |
iLayerHeight |
[0, 0.025, 0.1, 0.25, 0.5, 1, 1.5, 2.5, 4] |
m |
Location of layer boundaries. 0 at the soil surface with positive numbers indicating deeper layers |
mLayerDepth |
[0.025, 0.075, 0.15, 0.25, 0.5, 0.5, 1, 1.5] |
m |
Height of each active layer |
scalarCanopyIce |
0 |
kg m-2 |
Current ice storage in the canopy |
scalarCanopyLiq |
0 |
kg m-2 |
Current liquid water storage in the canopy |
scalarSnowDepth |
0 |
m |
Current snow depth |
scalarSWE |
0 |
kg m-2 |
Current snow water equivalent |
scalarSfcMeltPond |
0 |
kg m-2 |
Current ponded melt water |
scalarAquiferStorage |
1.0 |
m |
Current aquifer storage |
scalarSnowAlbedo |
0 |
- |
Current snow albedo |
scalarCanairTemp |
283.16 |
K |
Current temperature in the canopy airspace |
scalarCanopyTemp |
283.16 |
K |
Current temperature of the canopy |
mLayerTemp |
283.16 |
K |
Current temperature of each layer; assumed that all layers are identical |
mLayerVolFracIce |
0 |
- |
Current ice storage in each layer; assumed that all layers are identical |
mLayerVolFracLiq |
0.2 |
- |
Current liquid water storage in each layer; assumed that all layers are identical |
mLayerMatricHead |
-1.0 |
m |
Current matric head in each layer; assumed that all layers are identical |
SUMMA has built-in capability to save the model states at a given time step. This behaviour is controlled by runtime argument -r (for “restart”) and parameter year, month, day or end. Runs can be restarted from such a file by changing the name of the initConditionFile entry in fileManager.txt. Such files can also form the basis for a more appropriate initial conditions file when they result from long runs. This initial long run can be treated as a model warm-up period and the restart file can be used as an approximation of the slowly changing model states. The folder 0_tools that is part of this repository contains a script that can be used to strip the snow layers from a restart file if desired.