DOI: 10.5285/8a2b18eb-4720-4a40-a52a-b8f571b26b28
title: Analysis output of the MITgcm ocean model data for the Amundsen Sea (1920 to 2100)

description: This dataset contains high-resolution oceanographic model outputs generated using the MIT General Circulation Model (MITgcm) to study the projected ocean warming in the Amundsen Sea, Antarctica, under the RCP8.5 scenario. The primary focus of this dataset is to isolate and analyse the contributions of different atmospheric and oceanic drivers - namely, stronger poleward-shifted winds and changes in atmospheric thermodynamics - to future changes in ocean temperature and freshwater fluxes in this region. The spatial focus is on the Amundsen Sea continental shelf, a key area where Circumpolar Deep Water (CDW) intrudes and drives ice shelf melting. Data were generated using MITgcm, a high-resolution regional ocean model. The model was run under different configurations: with all modern atmospheric and oceanic drivers (ALL), with no anthropogenic changes (NONE), with only thermodynamic changes (THERMO), and with only wind changes (WIND). Additional ensemble runs and experiments with transient boundary conditions were performed to assess the robustness of the findings.

Funding: 
Computing hours were funded by the UKRI-JSPS project 'Quantifying Human Influence on Ocean Melting of the West Antarctic Ice Sheet' budget (NE/S011994/1)
My funding comes from the NERC-funded Doctoral Training Partnership INSPIRE DTP
description: The dataset was generated using the MIT General Circulation Model (MITgcm), a numerical model designed to simulate the dynamics of the ocean, atmosphere, and other geophysical fluids. The version of MITgcm used for these simulations includes high-resolution capabilities tailored for regional studies, particularly in polar regions.
- Model Configuration: The model was configured to focus on the Amundsen Sea, with a high-resolution grid that captures the detailed topography and bathymetry of the region as developed and discussed in Naughten et al. (2022) and Naughten et al. (2023). The horizontal resolution was fine enough to resolve key oceanographic features, such as the intrusions of Circumpolar Deep Water (CDW) onto the continental shelf.
- Forcing and Boundary Conditions: The simulations were forced with atmospheric and oceanic boundary conditions derived from global climate models under the RCP8.5 scenario. This includes surface wind stress, air temperature, humidity, and radiation. The dataset includes several experimental setups:
o ALL: All anthropogenic changes (both wind and thermodynamic).
o NONE: No anthropogenic changes (pre-industrial conditions).
o THERMO: Anthropogenic thermodynamic changes only.
o WIND: Anthropogenic wind changes only.
- Ensemble Simulations: each experiment comprises 9 ensemble runs. These ensembles provide a range of possible outcomes under the same external forcings, to ensure good representation of variability in the region.
The model was run from pre-industrial conditions (late 19th century) through to the year 2100, with a particular focus on the period 2070-2100 for future projections. Transient boundary conditions were used for some ensemble experiments to assess the sensitivity of the model outputs to boundary conditions.
description: ARCHER2 supercomputer used to run all the simulations
Python 3.6.3
Below are the packages used in the virtual environment:
 Package Version
------------------ ------------
matplotlib 3.3.4
netCDF4 1.2.8
numpy 1.19.5
pandas 1.1.5
Pillow 8.4.0
pytest 7.0.1
scipy 1.5.4
xarray 0.16.2
mitgcm_python (https://github.com/knaughten/mitgcm_python)

UaMITgcm (https://github.com/knaughten/UaMITgcm): repository created by Kaitlin Naughten and Jan De Rydt
description: For the accuracy and model configuration of MITgcm please see Naughten et al. (2022) and Naughten et al. (2023). The analysis data masks any grid cells not representing the ocean with NaN values. All data was quality controlled and Continuous Integration (CI) testing on the analysis script outputs was implemented where possible.