The atmosphere was forced with CGRF (Smith et al., 2014), Greenland solid and liquid discharges with Bamber et al. (2018) dataset, and river runoff with HydroGFD (Stadnyk et al., 2021). Initial and boundary conditions were taken from GLORYS2v3 (Masina et al., 2017).
The model was run from 2002 to 2017, and outputs were obtained as 5-day averages (for gridded variables). Iceberg trajectory files were generated daily.
The two simulations, SIL and CTL, only differ with respect to how the sea ice force on icebergs is parameterized. CTL follows the traditional drag parameterization present in NEMO-ICB (Marsh et al., 2015), while SIL introduces a new formulation where icebergs are locked in sea ice if the latter reaches a strength (proportional to sea ice concentration and thickness) that is capable of withstanding all the other forces acting on the iceberg without breaking. See Marson et al. (2023/2024) for more details.
Output files:
1. griddedOutput.nc
Here, you will find variables related to the ocean and sea ice that are outputted in the ANHA4 grid (544 x 800). All variables are placed at T-points (Arakawa-C grid):
• lat: latitude of each grid T-point in ANHA4
• lon: longitude of each grid T-point in ANHA4
• SIL_melttracer: vertically-integrated (m) passive tracer linked to iceberg melt by the end (Dec 31 2017) of the SIL simulation.
• CTL_melttracer: vertically-integrated (m) passive tracer linked to iceberg melt by the end (Dec 31 2017) of the CTL simulation.
• SIL_uovel_winter: U component of ocean velocity averaged between 0-100 m from 2004-2017 for the months of January to March in the SIL simulation.
• SIL_vovel_winter: V component of ocean velocity averaged between 0-100 m from 2004-2017 for the months of January to March in the SIL simulation.
• SIL_uivel_winter: U component of sea ice velocity averaged from 2004-2017 for the months of January to March in the SIL simulation.
• SIL_vivel_winter: V component of sea ice velocity averaged from 2004-2017 for the months of January to March in the SIL simulation.
2. CTL_trajfiles and SIL_trajfiles folders
The folders contain information from each particle (cluster of bergs) and the environmental conditions surrounding them at each simulation day for CTL and SIL runs. Each file contains a single variable, indicated by the filename. You will notice that there are four files for each variable (_01.nc through _04.nc). This was done because of the large number or particles generated by simulation (over 34,000). Therefore, the first 3 files have 10,000 particles each, and the fourth file has the remaining 4,025. The variables are matrices of size 5,840 by 10,000 (except for the ones in file *_04.nc, which are 5,840 by 4,025). Each column contains a time series for one particle, and each row represents day of simulation, from January 01, 2002 to December 31, 2017.
Therefore, if you wanted to plot the trajectory of the 10th 'calved' particle in CTL, you would plot all the rows of the 10th column of lon_01.nc versus all the rows of the 10th column of lat_01.nc contained in the CTL_trajfiles folder. Notice that the columns are usually padded with NaN's in the first and last rows, when the particle did not exist (was not yet calved or had already melted completely). So, you can calculate how many days a particle has survived by counting the rows with data in them.
The variables available for each simulation are:
• xi: particle's position in the ANHA4 grid along x
• yj: particle's position in the ANHA4 grid along y
• lat: particle's latitude
• lon: particle's longitude
• length, width, thickness: dimensions of icebergs contained in the particle
• icnt: sea ice concentration
• ithk: sea ice thickness at the particle's position
• uvel, vvel: particle velocity components
• uta, vta: wind velocity components at the particle's position
• uti, vti: sea ice velocity components at the particle's position
• uto, vto: ocean velocity components at the particle's position