Modeling ocean heat transport to the grounding lines of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica
Data files
May 08, 2024 version files 32.80 GB
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kohler.zarr.zip
8 GB
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pineisland.zarr.zip
8.37 GB
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README.md
1.55 KB
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smith.zarr.zip
7.73 GB
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thwaites.zarr.zip
8.70 GB
Aug 16, 2024 version files 33.12 GB
Abstract
In the Amundsen Sea Embayment (ASE) located in West Antarctica, the Pine Island, Thwaites, Smith, and Kohler glaciers are all experiencing rapid mass loss and rounding line retreat because of enhanced ocean thermal forcing from Circumpolar Deep Water (CDW) intruding into the ice shelf cavities. Here, we use 1 year of 6-hourly average outputs (September 1, 2006 to August 31, 2007) from the Southern Ocean high-resolution (SOhi) simulation and Lagrangian particles to backtrack the transport and cooling of warm water to the grounding lines of these glaciers. SOhi is a 1/24 degrees model with 225 vertical levels and includes sea ice, oceanic tides, and all ice shelves. In the ASE, SOhi model has a horizontal resolution of approximately 1.2km and a vertical resolution of 1.4 meters at the surface, 25.8 meters at 1,000 m, and 50 meters at 3000 m. The version of SOhi used in this analysis uses bathymetry is from the General Bathymetric Chart of the Oceans 2020 and ice cavity geometry is from BedMachine v1.39. The Lagrangian particles are advected using OceanParcels v2.4.1 using a fourth-order Runge-Kutta method with a 5 minutes timestep. We advect approximately 360,000 to 400,000 for particles for each glacier (approximately 1,000 particles released daily for 1 year). The trajectories and temperature of the particles are used to study the transport and cooling of warm CDW to the grounding line of Pine Island, Thwaites, Smith, and Kohler glaciers.
README: Particle trajectories advected using outputs from the Southern Ocean high-resolution (SOhi) simulation for Pine Island, Thwaites, Smith, and Kohler glaciers
Version Changes
2024 Aug 14: Added SOhi mean temperature and salinity field (SOhi_ASE_MeanTS.nc) used for model validation.
Description of the data and file structure
Particle trajectories for each of the four glaciers (Pine Island, Thwaites, Smith, and Kohler) is stored in their own corresponding zipped -.zarr format. Unzipped the folder and the zarr store can be accessed with python using:
import zarr
dataset = zarr.open('path/to/file.zarr', mode='r')
var_data = dataset['var_name']
Replace 'var_name' with the variable of interest. The available variables are:
Dimensions
obs : Observation ID
trajectory : Particles ID
Data Variables (dimension = trajectory x obs):
age : Age of particle (in seconds), starting from when the particles are initialized
time : Time of particle (in seconds) with respect to the velocity fields. Particles with the same time is advected using the same fields.
lat : Latitude (-90 to 90) of particle
lon : Longitude (-180 to 180) of particle
z : Depth of particle (meters)
salinity : Salinity sampled from SOhi outputs (psu)
temperature : Potential temperature sampled from SOhi outputs (C)
Note that the last few timesteps are filled with nan and does not contain any data. This is due to a mismatch between the prescribed chunk size and the total run time.
Note that the stuck particles (particles advected into a dry cell) have not been removed from the dataset. These particles should be filtered and removed during analysis.
1-year mean temperature and salinity
One-year mean temperature and salinity from SOhi over the duration of the particles run are provided as a netCDF file. This temperature and salinity dataset was used to to compare SOhi with observational data. The domain of this dataset is 140°W to 65°W and 75.5°S to 69°S.
import netCDF4 as nc
dataset = nc.Dataset('path/to/file.nc', mode='r')
var_data = dataset['var_name']
Replace 'var_name' with the variable of interest. The available variables are:
Data Variables:
depth : depth at cell's center in meters (size = 225)
lat : Latitude at cell's center in degrees East (size = 517)
lon : Longitude at cell's center in degrees North (size = 1800)
salinity : 1-year mean salinity in psu (size = (225, 517, 1800))
temperature : 1-year mean potential temperature in degrees Celsius (size = (225, 517, 1800))