8. Glacier accumulation and ablation#
The FEST model can simulate the glacier accumulation and ablation.
Glacier ablation is simulated by using the models implemented for snow simulation.
The keyword doy-snow-ice-transformation defines the day of the year (1-365) in which
snow water equivalent still available is transformed to ice water equivalent.
In the configuration file the user must define 5 sections. Each section sets a
parameter that can be assigned as a scalar value or as a grid map.
Some of the parameters can change within the simulation period: [melt-coefficient],
[melt-threshold-temperature], and [hydraulic-conductivity].
In this case the user must use the NetCDF format for the input maps
that contain changing parameter values. Keywords in the glacier configuration
file (usually named glacier.ini) are listed and described in the following tables:
Table 8.1, Table 8.2, Table 8.3, Table 8.4,
Table 8.5, and Table 8.6
Keyword |
Description |
Requirements |
|---|---|---|
|
day of the year (1-365) in which snow water equivalent still available is transformed to ice water equivalent |
Optional. If keyword is missing, or |
Keyword |
Description |
Requirements |
|---|---|---|
|
Currently only the degree-day model based on air temperature data is implemented: 1=Degree-Day |
Mandatory |
|
Scalar value to be used on the entire domain |
Optional. |
|
Name of file of the grid map. |
Required when parameter values are assigned through a grid map |
|
Input file format |
Available options: |
|
epsg coordinate reference system code |
Required when parameter values are assigned through a grid map |
|
Variable’s name in net-cdf file |
Required when input map is in net-cdf format |
|
Date and time of the first map to read from net-cdf file |
Optional. |
|
Sync the initial map with the simulation initial time. |
Alternative option to time. Available options: 1 = map is synced, 0 = map is not synced |
Keyword |
Description |
Requirements |
|---|---|---|
|
Ice water equivalent initial value (m) |
Optional. Default value = 0 |
|
Scalar value to be used on the entire domain |
Optional. |
|
Name of file of the grid map. |
Required when parameter values are assigned through a grid map |
|
Input file format |
Available options: |
|
epsg coordinate reference system code |
Required when parameter values are assigned through a grid map |
|
Variable’s name in net-cdf file |
Required when input map is in net-cdf format |
|
Date and time of the first map to read from net-cdf file |
Optional. |
|
Sync the initial map with the simulation initial time. |
Alternative option to time. Available options: 1 = map is synced, 0 = map is not synced |
Keyword |
Description |
Requirements |
|---|---|---|
|
Ice melt coefficient (mm/day/°C) |
Mandatory |
|
Scalar value to be used on the entire domain |
Optional. |
|
Name of file of the grid map. |
Required when parameter values are assigned through a grid map |
|
Input file format |
Available options: |
|
epsg coordinate reference system code |
Required when parameter values are assigned through a grid map |
|
Variable’s name in net-cdf file |
Required when input map is in net-cdf format |
|
Date and time of the first map to read from net-cdf file |
Optional. |
|
Sync the initial map with the simulation initial time. |
Alternative option to time. Available options: 1 = map is synced, 0 = map is not synced |
Keyword |
Description |
Requirements |
|---|---|---|
|
air temperature above which ice melt starts (°C) |
Mandatory |
|
Scalar value to be used on the entire domain |
Optional. |
|
Name of file of the grid map. |
Required when parameter values are assigned through a grid map |
|
Input file format |
Available options: |
|
epsg coordinate reference system code |
Required when parameter values are assigned through a grid map |
|
Variable’s name in net-cdf file |
Required when input map is in net-cdf format |
|
Date and time of the first map to read from net-cdf file |
Optional. |
|
Sync the initial map with the simulation initial time. |
Alternative option to time. Available options: 1 = map is synced, 0 = map is not synced |
Keyword |
Description |
Requirements |
|---|---|---|
|
Ice hydraulic conductivity (m/s) used to calculate intercell lateral flow |
Mandatory |
|
Scalar value to be used on the entire domain |
Optional. |
|
Name of file of the grid map. |
Required when parameter values are assigned through a grid map |
|
Input file format |
Available options: |
|
epsg coordinate reference system code |
Required when parameter values are assigned through a grid map |
|
Variable’s name in net-cdf file |
Required when input map is in net-cdf format |
|
Date and time of the first map to read from net-cdf file |
Optional. |
|
Sync the initial map with the simulation initial time. |
Alternative option to time. Available options: 1 = map is synced, 0 = map is not synced |
Keyword |
Description |
Requirements |
|---|---|---|
|
Liquid phase inside icepack initial value (m) |
Optional. Default value = 0 |
|
Scalar value to be used on the entire domain |
Optional. |
|
Name of file of the grid map. |
Required when parameter values are assigned through a grid map |
|
Input file format |
Available options: |
|
epsg coordinate reference system code |
Required when parameter values are assigned through a grid map |
|
Variable’s name in net-cdf file |
Required when input map is in net-cdf format |
|
Date and time of the first map to read from net-cdf file |
Optional. |
|
Sync the initial map with the simulation initial time. |
Alternative option to time. Available options: 1 = map is synced, 0 = map is not synced |
An example of glacier.ini configuration file follows.
doy-snow-ice-transformation = 274 # 1st October
[melt-model]
scalar = 1 # 1 = degree-day
[melt-coefficient]
file = ./data/melt_factor.nc
format = net-cdf
variable = melt_factor
epsg = 32632
sync-initial-time = 1
[melt-threshold-temperature]
scalar = 0.
[hydraulic-conductivity]
scalar = 0.01
[ice-water-equivalent]
file = ./data/initial_ice_depth.asc
format = esri-ascii
epsg = 32632