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SurfaceBoundaryEnthalpy.f90
SurfBoundarySolver
Surf Enth
, Mass Balance
, Densi
, Firn
, Melting
, Refreeze
, Accu
, Rad_Fact
, Rain
, PotRad
Depth
and SurfGrad
from the FlowDepth SolverSurfBoundarySolver is a pseudo-solver which compute surface mass balance and Dirichlet surface boundary condition for the Enthalpy solver. It takes into account firn heating processes by solving vertical melt-water percolation and refreezing.
The solver uses the provided air temperature (and precipitation) daily record to compute the associated mean surface characteristic of the glacier over the time period covered by the provided data time-serie. It outputs the following variables:
Mass Balance
(m w.eq./yr): Mean surface mass balance Surf Enth
(J/kg) : Enthalpy value bellow active layer. Can be use as a Dirichlet condition in the Enthalpy SolverDensi
(kg/m3): Density field in 3DFirn
(m w. eq.) : Firn thicknessMelting
(m w.eq./yr) : Surface meltingRefreeze
(m w.eq./yr) : Amount of refreezing (superimposed ice)Accu
(m w.eq./yr) : Snow accumulationRad_fact
(m w.eq./(W/m2)) : Melting factor for radiationRain
(m w.eq./yr) : Amount of rainPotRad
(W/m2) : Potential solar radiationThe mass balance model is based on a degree day model that takes into account potential solar radiation. Mean Enthalpy at 10m-depth (bellow active layer), is computed by solving the heat equation on a 1D vertical profile forced by a mean annual cycle of air temperature and precipitation determined from the data. This is done for each surface nodes using a Crank-Nicholson scheme on a 6 cm resolution grid at daily time-step. It takes into account of seasonal change of the density profile and allow percolation of water only where density is lower than 800 kg/m3. More details about the model can be found in:
Gilbert, A., Sinisalo, A., Gurung, T. R., Fujita, K., Maharjan, S. B., Sherpa, T. C., & Fukuda, T. (2020). The influence of water percolation through crevasses on the thermal regime of a Himalayan mountain glacier. The Cryosphere, 14(4), 1273–1288. https://doi.org/10.5194/tc-14-1273-2020