NEMO v4.2 eORCA1 data with RIS, FRIS and LCIS explicit

PROJECT OPEN

https://www.katofthesea.com/project-open

OBJECTIVES

As a first step towards better representing AABW source waters in NEMO global ocean 1° (eORCA1), we explicitly simulate circulation beneath Filchner-Ronne (FRIS), Larsen C (LCIS), and Ross (RIS) ice shelves. These ice shelves were chosen due to their role in the formation and setting of properties of the parent waters of AABW.

METHODOLOGY

• NEMO version 4.2 Beta

Forced with 2 cycles of CORE forcing for a reference “Closed” cavity run and an “Open” run with FRIS, LCIS and RIS represented.

• Inform initial conditions using an idealized regional configuration of each ice shelf.

PROVIDED HERE:

NAMELISTS:

- NEMO reference namelist (namelist_ref; also available with NEMO code), OPEN configuration (namelist_core_ia_cfg) namelist and sea ice namelists (namelist_ice_ref and namelist_ice_cfg). 

Unless stated otherwise in the “cfg” namelist, the simulation uses the namelist choices provided in the “ref” namelist. The namelist_core_ia_cfg is a namelist specific to a global ocean configuration (ORCA2, ORCA1, ORCA025 etc) forced by interannual core winds. For more information on all the namelist parameters included in these namelists, please refer to the NEMO reference manual available on Zenodo (10.5281/zenodo.6334656). 

DOMAIN FILES AND INITIAL CONDITIONS: 

- Initial conditions where data inside the cavity is informed using an idealized regional configuration with World Ocean Atlas (WOA; https://www.nodc.noaa.gov/OC5/woa18/woa18data.html) restoring at the boundaries. The data in the cavities is merged with WOA with a smoothing spline applied along the ice shelf front.

- A domain file containing bathymetry and ice shelf draft with FRIS, LCIS and RIS open along with accompanying mesh mask file.

- The adapted eddy viscosity files where viscosity varies south of 65 degrees South according to grid cell size.

- A freshwater flux file where the melt rate from all cavities except FRIS, LCIS and RIS is prescribed. Inside the "Open" cavities, the melt paramaterization is turned off and the location of melt is moved to the grounding line in case in the future we would like to include the flux from grounding line rives. 

MODEL OUTPUT:

The data uploaded in this zip file is split into the output from the "Closed" and "Open" runs and is listed under eORCA1_output. Here the temperature and salinity fields used for comparison with WOA are provided (1981-2009), along with specific sections extracted using the PAGO functions (https://www.whoi.edu/science/PO/pago/) along FRIS and RIS for certain dates that correspond to CTD sections in the area. To facilitate easy plotting of the example scripts provided, we have also extracted the thermohaline and velocity fields for FRIS cavity and adjacent continental shelf. The user can use these for a first try with the scripts provided and then move on to extracting their areas and dates of interest from the regional 1981-2009 files. 

EXAMPLE SCRIPS:

To get the user familiar with the provided data, we have provided example scripts for extracting the data (open_eORCA_FRIS), plotting bathymetry and T-S (plot_bathy_T_S) and plotting the meridional overturning function and barotropic stream function in the cavity (plot_MOC_BSF_melt). In this same script the melt rate pattern is plotted and the net melt over various time periods corresponding to observational studies is calculated using calculating_net_melt.

Additionally, a script plotting temperature and salinity across FRIS ice shelf front for the period February-March 1995 is provided and can be adapted and used to plot the other sections of data provided in this zip. 

ACKNOWLEDGEMENTS AND FINANCIAL SUPPORT

Katherine Hutchinson received financial support of the European Union’s Horizon 2020 research and innovation programme Marie Skłodowska-Curie grant agreement No 898058 (Project OPEN). Nicolas Jourdain received support from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 101003536 (ESM2025). Pierre Mathiot acknowledges support from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 820575 (TiPACCs). This work was performed using HPC resources from GENCI–IDRIS (Grant 2021- A0100107451) and from the IPSL Mesocentre ESPRI.

Project OPEN is a participant in the h2020 open access data pilot.