Gulf Stream Separation

Model Runs

We are actively working through creating a series of downscaled runs focused on the Gulf Stream along the eastern US seaboard and downstream of its separation from the continental slope near Cape Hatteras, NC. Each execution of the MITgcm is assigned a simulation id and a simulation phase.

The simulation id corresponds to the regional mesh configuration, boundary and atmospheric input deck sources, and the target subgridscale parameterization and time-stepping parameters. For each simulation id, the model is transitioned through multiple phases. Early in a simulation, the model interior goes through a period of adjustment where gravity waves and other spurious noise propagates through the numerical ocean. During these early phases, the time steps are usually smaller and the viscosity and diffusivity is artificially larger in order to quickly damp out the noise while maintaining numerical stability. We gradually change these parameters through various phases in the simulation to reach the target parameters for production runs. Once we reach production runs, multi-year model runs are executed to create sufficiently long datasets for driving the next down-scaling run.

Simulation ID : mitgcm50-z75

  • Region Boundaries: ( 1280 x 960 lateral grid cells )

  • Equation of State : MDJWF

  • Numerics

  • Ocean Boundary Conditions

    • Source : HYCOM 1/50 Degree Resolution ( forced by 2003 atmospheric conditions, Neutral NAO year)

    • Period: 365 days, forced daily

    • Preprocessing: Ensemble average HYCOM model years 17-21

  • Atmospheric Boundary Conditions

    • Package: CheapAML

    • Source: ERA Interim (2003)

    • Period: 365 days, forced daily

    • Preprocessing: Interpolated onto model grid with piecewise cubic interpolation.

  • SGS

    • Background Lateral Laplacian Viscosity (Target) : 10 m^2/s (Schmidt Number = 1)

    • Background Lateral Biharmonic Viscosity : -7.9E7 m^4/s (Schmidt Number = 1)

    • Background Vertical Viscosity: 1E-5 m^2/s (Schmidt Number = 1)

    • Free Slip Bottom/Sidewall boundary conditions + Quadratic Bottom Drag ( Cd = 2.0E-3 1/m )

    • KPP

  • Simulation Phases :

    • spinup-01

      • Time-step : 0.5s

      • Lateral Laplacian Viscosity : 500 m^2 / s (Schmidt Number = 1)

      • Model Integration Period: Jan 1, 2003 12:00AM - Jan 1, 2003 12:00PM

    • spinup-02

      • Time-step : 5.0s

      • Viscosity : 500 m^2 / s (Schmidt Number = 1)

      • Model Integration Period: Jan 1, 2003 12:00PM - Jan 2, 2003 12:00AM

    • spinup-03

      • Time-step : 30.0s

      • Viscosity : 500 m^2 / s (Schmidt Number = 1)

      • Model Integration Period: Jan 2, 2003 12:00AM - Jan 2, 2003 12:00PM

    • spinup-04

      • Time-step : 60.0s

      • Viscosity : 100 m^2 / s (Schmidt Number = 1)

      • Model Integration Period: Jan 2, 2003 12:00PM - Jan 4, 2003 12:00AM

    • spinup-05

      • Time-step : 120.0s

      • Viscosity : 100 m^2 / s (Schmidt Number = 1)

      • Model Integration Period: Jan 4, 2003 12:00AM - Jan 11, 2003 12:00AM

    • spinup-06

      • Time-step : 12.0s

      • Viscosity : 20 m^2 / s (Schmidt Number = 1)

      • Model Integration Period: Jan 11, 2003 12:00PM - Jan 31, 2003 12:00AM

Simulation Monitoring

As the MITgcm runs, we are regularly parsing the monitoring statistics and computing other time-series output. This data is posted to Big Query and visualized in Data Studio. This allows us to keep track of simulations running on Google Cloud Platform, NCAR's Cheyenne supercomputer, and a departmental cluster at Florida State University.

The dashboard below is an interactive panel. You can change the date range and the simulation id and phase