Module enthalpy
Warning: this rather complex module was not much tested so far, use it with care!
Description:
This IGM module models the ice enthalpy, which permits to jointly model the ice temperature, as well as the water content created when the temperature hits the pressure melting points, and therefore energy conservation, which is not the case when modelling the sole temperature variable. The model is described in (Aschwanden and al, JOG, 2012). Check at the IGM technical paper for further details [1].
[1] Concepts and capabilities of the Instructed Glacier Model 3.X.X, Jouvet and al.
The enthalpy module builds upon the iceflow module. To ensure proper functionality, follow these requirements:
- Activate the
vertical_iceflowmodule to provide the vertical velocity. - Set
params.dim_arrhenius = 3. - Set
params.new_friction_param = true. - Ensure sufficient retraining by setting
retrain_iceflow_emulator_freq = 1. Optionally, setretrain_iceflow_emulator_nbitto a value greater than 1 for improved performance.
Contributors: G. Jouvet
This implementation is largely inspired from the one implemented in PISM. Other references that have helped are (Kleiner and al, TC, 2015) and (Wang and al, 2020).
Config Structure
enthalpy:
water_density: 1000.0
spy: 31556926.0
ki: 2.1
ci: 2009.0
Lh: 3.34e+5
KtdivKc: 1e-1
claus_clape: 7.9e-8
melt_temp: 273.15
ref_temp: 223.15
till_friction_angle: 30.0
till_friction_angle_bed_min: null
till_friction_angle_bed_max: null
till_friction_angle_phi_min: 15.0
till_friction_angle_phi_max: 45.0
uthreshold: 100.0
drain_rate: 0.001
till_wat_max: 2.0
drain_ice_column: True
default_bheatflx: 0.065
temperature_offset_air_to_ice: 0.0
tauc_min: 1.0e+5
tauc_max: 1.0e+10
Parameters
| Name | Type | Units | Description | Default Value |
|---|---|---|---|---|
| water_density | float | \( kg~m^{-3} \) | Constant of the Water density | 1000.0 |
| spy | float | \( s y^{-1} \) | Number of seconds per years | 31556926.0 |
| ki | float | \( W~m^{-1}~K^{-1} \) | Conductivity of cold ice (Aschwanden and al, JOG, 2012) | 2.1 |
| ci | float | \( W~s~kg^{-1}~K^{-1} \) | Specific heat capacity of ice (Aschwanden and al, JOG, 2012) | 2009.0 |
| Lh | float | \( W~s~kg^{-1} = E \) | Latent heat of fusion (Aschwanden and al, JOG, 2012) | 334000.0 |
| KtdivKc | float | \( \frac{Kt}{Kc} \) | Ratio of temp vs cold ice diffusivity (Aschwanden and al, JOG, 2012) | 1e-1 |
| claus_clape | float | \( K~Pa^{-1} \) | Clausius-Clapeyron constant (Aschwanden and al, JOG, 2012) | 7.9e-08 |
| melt_temp | float | \( K \) | Melting point at standard pressure (Aschwanden and al, JOG, 2012) | 273.15 |
| ref_temp | float | \( K \) | Reference temperature (Aschwanden and al, JOG, 2012) | 223.15 |
| till_friction_angle | float | \( \circ \) | Till friction angle in the Mohr-Coulomb friction law | 30.0 |
| till_friction_angle_bed_min | float | \( \circ \) | Minimum till friction angle at the bed | None |
| till_friction_angle_bed_max | float | \( \circ \) | Maximum till friction angle at the bed | None |
| till_friction_angle_phi_min | float | \( \circ \) | Minimum till friction angle phi | 15.0 |
| till_friction_angle_phi_max | float | \( \circ \) | Maximum till friction angle phi | 45.0 |
| uthreshold | float | \( \frac{m}{y} \) | Threshold velocity | 100.0 |
| drain_rate | float | \( \frac{m}{y} \) | Drain rate at 1 mm/y (Bueler and Pelt, GMD, 2015) | 0.001 |
| till_wat_max | float | \( m \) | Maximum water till thickness (Bueler and Pelt, GMD, 2015) | 2.0 |
| drain_ice_column | float | \( m \) | Transform the water content beyond a threshold into water, drain it, and add it to basal melt rate | True |
| default_bheatflx | float | \( W~m^{-2} \) | Geothermal heat flux | 0.065 |
| temperature_offset_air_to_ice | float | \( K \) | Offset between the air temperature and the ice temperature | 0.0 |
| tauc_min | float | \( Pa \) | Lower bound for tauc | 100000.0 |
| tauc_max | float | \( Pa \) | Upper bound for tauc | 10000000000.0 |