Model code to estimate the surface mass balance (SMB) of a glacier's ablation zone from UAV data and ice thickness. This repository contains and presents a method to determine the SMB in the entire ablation zone of two glaciers by combining UAV acquired 3D data and ice thickness measurements through the continuity-equation. Study area concerns Vadret da Morteratsch and Vadret Pers glaciers in the southeastern part of Switzerland (Engadin - Bernina - Graubünden).
Van Tricht, L., Huybrechts, P., Van Breedam, J., Vanhulle, A., Van Oost, K., and Zekollari, H.: Estimating surface mass balance patterns from UAV measurements on the ablation area of the Morteratsch-Pers glacier complex (Switzerland), The Cryosphere Discuss. [preprint], https://doi.org/10.5194/tc-2021-94, in review, 2021.
- Surface elevation changes
- Surface velocity
- Ice thickness
--> Bs=∂h/∂t+ ∇.q <-- (Continuity equation, reverted to obtain the mass balance)
where:
Bs = surface mass balance ∂h/∂t = surface elevation changes ∇.q = ice flux divergence
In the ablation zone, all units are in metres of ice equivalent per year (m i.e. yr^-1) If the method is applied to any other part of the glacier, specific attention has to be paid to the unit of each quantity in the continuity equation.
The model structure consists of the following elemennts:
a) Main script (MAIN.m): All submodel codes are integrated in one main script (Main.m). This serves as the main model script and has to be run to obtain model results.
b) Calculate velocities: Surface velocities were calculated based on the Imgraft algorithm and are not added in this repository. For the model code of Imgraft, we refer to: https://github.com/grinsted/ImGRAFT
c) Load input data: The different input data which are required for the model are:
- Surface elevation changes (preferably from flow corrected DEMs)
- Surface velocities (from feature tracking)
- Ice thickness dataset
d) Calc_fluxdiv.m: This function calculates the ice flux divergence. Hence, it is the main function to be applied in the model. Four options are available for filtering the gradients:
- meanmed_smooth.m = filtering using a mean/median box filter
- exp_smooth.m = filtering using an exponential filter
- gaus_smooth.m = filtering using a gaussian filter
e) Calculate SMB: Add the elevation differences and the calculated ice flux divergence to obtain an estimate of the surface mass balance
The datasets of Vadret da Morteratsch and Vadret Pers can be requested via lander.van.tricht@vub.be