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Getting Started

Welcome to the documentation for the Near-Present-Day simulations developed by the National Oceanography Centre 👋

Introduction 🌊

As part of the Atlantic Climate and Environment Strategic Science (AtlantiS) project, the National Oceanography Centre is developing a full suite of global ocean model configurations to perform multi-decadal Near-Present-Day simulations.

Our aim is that the Near-Present-Day simulations will be kept up to date with a 1-3 month lag.

Configurations 🌐

The Near-Present-Day simulations consists of a hierarchy of three ocean sea-ice configurations of NEMO v4.2 at 1\(^{\circ}\), 1/4\(^{\circ}\) and 1/12\(^{\circ}\) nominal horizontal resolution.

The key features of each configuration are summarised below:

  • 1\(^{\circ}\) nominal horizontal resolution (j=331, i=360).
  • 75 vertical z\(^{*}\) levels.
  • Eddy induced velocities determined using the Gent and McWilliams (1990) diffusion scheme.
  • Coupled to SI\(^{3}\) sea ice engine.
  • Initialised from World Ocean Atlas 2023 (1971-2001) climatology.
  • Forced with JRA55-do (v1; 1976-2023) and climatologically adjusted ERA-5 (v1; 1976-present) atmospheric forcing.
  • 1/4\(^{\circ}\) nominal horizontal resolution (j=1206, i=1440).
  • 75 vertical z\(^{*}\) levels.
  • Eddy induced velocities determined using the grid-scale dependent Gent and McWilliams (1990) diffusion scheme.
  • Coupled to SI\(^{3}\) sea ice engine.
  • Initialised from World Ocean Atlas 2023 (1971-2001) climatology.
  • Forced with JRA55-do (v1; 1976-2023) and climatologically adjusted ERA-5 (v1; 1976-present) atmospheric forcing.
  • 1/12\(^{\circ}\) nominal horizontal resolution (j=3605, i=4320).
  • 75 vertical z\(^{*}\) levels.
  • Coupled to SI\(^{3}\) sea ice engine.
  • Initialised from World Ocean Atlas 2023 (1971-2001) climatology.
  • Forced with climatologically adjusted ERA-5 (v1; 1976-present) atmospheric forcing.

For more details on each model configuration see Deep Dives: Model Configurations.

Quick Start 🚀

Installation

To get started, check out and set up an instance of the NPD GitHub repository:

git clone git@github.com:NOC-MSM/NOC_Near_Present_Day.git
Helpful Tip...
  • It is not advised to checkout the respository in your home directory.

Next, run the setup script to download NEMO & compile the tools and configurations:

cd NOC_Near_Present_Day

./setup

cd NOC_Near_Present_Day

./setup -s Archer2

By default, the script will setup for the Anemone HPC, which is ideally suited for development tasks or for the fast turnaround of smaller NPD configurations (e.g., eORCA1 or eORCA025).

Running An Experiment

The global eORCA1 and eORCA025 configurations are ready to run. Here, we provide a brief overview on how to setup a first experiment with the default atmospheric forcing JRA55-do on the Anemone HPC:

All that is required to run the eORCA1 Near-Present-Day configuration starting from 1976 is: 

cd nemo/cfgs/GLOBAL_QCO/eORCA1

sbatch run_nemo552_40x_10n.slurm

There are a few important variables to set in the runscript.

The default configuration will generate a 10-year simulation without spin-up which is divided into 1-year jobs: 

# ========================================================
# PARAMETERS TO SET
# time units used here for restart frequency and simulaion length
TIME_UNITS=0 # 0=years ; 1=days ; 2=hours
# Restart/resubmission frequency (in TIME_UNITS)
FREQRST=1
# job-step initial time step (0: infer from time.step)
# IT000 != 0 -> auto-resubmission is switched OFF
IT000=0
#
# Simulation original starting time step (unchanged for LENGTHxTIME_UNITS)
ITBEGIN=1
# Simulation length (in TIME_UNITS) 
LENGTH=10
# Name of this script (to resubmit)
SCRIPTNAME=run_nemo552_40x_10n.slurm
# If conducting the repeat and reset T and S spinup set SPIN to 1, else set to 0
SPIN=0

To run with ERA-5 atmospheric forcing, use the following command to modify the namelist file: 

cp namelist_cfg_ERA5 namelist_cfg

All that is required to run the eORCA025 Near-Present-Day configuration starting from 1976 is: 

cd nemo/cfgs/GLOBAL_QCO/eORCA025

sbatch run_nemo1326_96x_26n.slurm

There are a few important variables to set in the runscript.

The default configuration will generate a 3-year simulation without spin-up which is divided into 1-year jobs: 

# ========================================================
# PARAMETERS TO SET
# time units used here for restart frequency and simulaion length
TIME_UNITS=0 # 0=years ; 1=days ; 2=hours
# Restart/resubmission frequency (in TIME_UNITS)
FREQRST=1
# job-step initial time step (0: infer from time.step)
# IT000 != 0 -> auto-resubmission is switched OFF
IT000=0
#
# Simulation original starting time step (unchanged for LENGTHxTIME_UNITS)
ITBEGIN=1
# Simulation length (in TIME_UNITS) 
LENGTH=3   
# Name of this script (to resubmit)
SCRIPTNAME=run_nemo1326_96x_26n.slurm
# If conducting the repeat and reset T and S spinup set SPIN to 1, else set to 0
SPIN=0

To run with ERA-5 atmospheric forcing, use the following command to modify the namelist file: 

cp namelist_cfg_ERA5 namelist_cfg