[MITgcm-support] Effect of 'vectorInvariantMomentum' flag on first order circulation

[Ryan Abernathey]

Does anyone have any thoughts on this? Switching from

vectorInvariantMomentum=.FALSE.,
to
vectorInvariantMomentum=.TRUE.,

made our ACC flow backwards! Not a small effect!! It is a bit troubling...

-Ryan



On Thu, Feb 23, 2017 at 2:58 PM, Dhruv Balwada <db194 at nyu.edu> wrote:

> Hi MITgcm community,
>
> I have recently been stumped an issue with the MITgcm vectorInvariantMomentum
> flag.
>
> **The model setup** is meant to be an ideal representation of the ACC
> (following Abernathey and Cessi 2014). It has the following components -
> a) Linear temperature relaxation at the surface
> b) Zonal wind with sinusoidal structure
> c) Initial temp field is zonally symmetric and the thermocline shoals from
> north to south (similar to the ACC).
> d) Resolution is 20km, and domain size is 2000km * 2000km.
> e) Zonally periodic and meridional walls
> f) A zonal gaussian bump is the topographic feature, which is meridionaly
> independent.
>
> **The issue** I am facing is that the circulation pattern completely
> changes when I change the "vectorInvariantMomentum" flag.
> When the flag is set to false (default), the model recreates an ACC like
> flow. Flow is from west to east and strongly perturbed by the presence of
> topography.
> When the flag is set to true (default), the model does something else.
> Flow is from east to west, with a strong boundary flow from the west to
> east near the southern boundary.
>
> Any help would be appreciated.
>
> I have posted some visualizations and data file here -
> https://sites.google.com/site/dhruvbalwada/blog/
> mitgcmissuewithvectorinvariantmomentumflag
>
> Here is the data file (obviously the vectorinvariantmomentum flag is
> changed between two runs.
>
>  &PARM01
>
> # viscosity
>
>  viscAr=5.6614E-04,
>
>  viscC4Leith=2.15,
>
>  viscC4Leithd=2.15,
>
>  viscA4GridMax=0.8,
>
>  useAreaViscLength=.TRUE.,
>
>  highOrderVorticity=.TRUE.,
>
> # diffusivity
>
>  tempAdvScheme=7,
>
>  diffKrT=5.44e-7,
>
>  saltStepping=.FALSE.,
>
>  staggerTimeStep=.TRUE.,
>
> # multiDimAdvection=.TRUE.,
>
>  vectorInvariantMomentum=.TRUE.,
>
> # initial vertical profiles of T and S
>
>  sRef=30*35.0000,
>
> # equation of state
>
>  eosType='LINEAR',
>
>  tAlpha=2.0E-04,
>
>  sBeta=0.0,
>
> # boundary conditions
>
>  no_slip_sides=.FALSE.,
>
>  no_slip_bottom=.TRUE.,
>
> # bottomDragLinear=1.1E-03,
>
>  bottomDragQuadratic=0.0021,
>
> # physical parameters
>
>  f0=-0.9E-04,
>
>  beta=1.0E-11,
>
>  gravity=9.81,
>
> # implicit diffusion and convective adjustment
>
>  implicitDiffusion=.TRUE.,
>
>  implicitViscosity=.TRUE.,
>
> # exact volume conservation
>
>  exactConserv=.TRUE.,
>
> # C-V scheme for Coriolis term
>
>  useCDscheme=.FALSE.,
>
> # partial cells for smooth topography
>
>  hFacMin=5.0E-02,
>
> # file IO stuff
>
>  readBinaryPrec=64,
>
>  useSingleCpuIO=.TRUE.,
>
>  debugLevel=1,
>
>  &
>
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>
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