Boundary conditions over an ice shelf

pf4d

Hello,
I have been asked to apply a thermal boundary condition over an ice shelf similar in form to equation (27) of Larour et al., (2012). However, I do not see any note of this boundary condition within the documentation. Is this boundary condition automatically applied? Is there an enthalpy boundary condition as well?

Also, I have been asked to modify the code in order to allow a user-specified constant function \phi = \phi(x,y) for this value. Can anyone direct me to the specific part of the code I would need to modify in order to do this, and/or offer suggestions for its implemention? Ideally, I would like the function to be time dependent as well, such that \phi = (x,y,t).

Thanks much!
Evan Cummings

pf4d

So, I believe that I have found the part of the code that I'll need to modify, the "EnthalpyAnalysis" class:

https://issm.jpl.nasa.gov/doxygen/chtml/classEnthalpyAnalysis.html#a20c822660756a813f28e191b57b43731

From reading the code (which is quite readable, nicely done!) it appears that you have split the boundaries into separate shelf and sheet domains. Over the shelf, you apply the condition

scalar_ocean = gauss->weight * Jdet * rho_water * mixed_layer_capacity * thermal_exchange_vel * h_pmp / (heatcapacity * rho_ice)

This is the enthalpy form of equation (27) of Larour et al., (2012). No problem.

The question now is, how would you suggest that I create a new variable that can be used from both the matlab and python interfaces? I imagine there are several different files I'll need to modify in order to create a new variable...

heleneseroussi

Hi Evans,
This is indeed the part of the code where the boundary condition is set-up, and the treatment is different for grounded and floating ice as the interactions with the rock and the ocean underneath are very different, which is why there are two different CreatePVector.

For now you can either specify a temperature (using md.thermal.spctemperature) or use the Holland and Jenkins condition as you saw in the code. There is no easy way to change this condition, it would require to create a new class for the basal forcings, transfer the new fields into c and code the new condition in the EnthalpyAnalysis: when this new basal forcings class is used, which is a lot of work.

Best,
Helene