DOI: 10.5061/dryad.8sf7m0cwt
title: Modeling ocean heat transport to the grounding lines of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica

description: 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.
description: # 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:
 &gt; import zarr &gt; &gt; dataset =
 zarr.open('path/to/file.zarr', mode='r') &gt; &gt;
 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. &gt; import netCDF4 as nc &gt; &gt; dataset =
 nc.Dataset('path/to/file.nc', mode='r') &gt; &gt;
 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))