[MITgcm-support] MITgcm-support Digest, Vol 158, Issue 17

Wed Aug 31 05:42:23 EDT 2016

Hi Jianfen,

spinning up a sea ice model usually takes a few model years (starting from no ice cover!), so if you construct a good set of mean initial fields, the model will have an even shorter spinup, except for multi-year ice regions. Why don’t you try both and learn from the difference.

Martin

> On 31 Aug 2016, at 04:27, weijianfen1988 at 163.com wrote:
> 
> Hi Dimitris,
> 
> Thanks for your help. 
> I wonder how  the initial sea ice conditions could affect the MITgcm simulation results of Arctic sea ice. I mean, are the simulation results vary greatly when using PIOMAS sea ice data at a particular year or using PIOMAS sea ice climatology, or using the climatologies calculated during different time periods (considering the rapid decline of Arctic sea ice cover)?
> 
> Thank you.
> Jianfen
> 
> weijianfen1988 at 163.com
>  
> From: mitgcm-support-request
> Date: 2016-08-28 00:00
> To: mitgcm-support
> Subject: MITgcm-support Digest, Vol 158, Issue 17
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> Today's Topics:
>  
>    1. Re: sea ice volume conservation (Martin Losch)
>       (Georgy Manucharayan)
>    2. Re: Sea ice initial conditions in MITgcm
>       (Menemenlis, Dimitris (329C))
>  
>  
> ----------------------------------------------------------------------
>  
> Message: 1
> Date: Fri, 26 Aug 2016 09:48:31 -0700
> From: Georgy Manucharayan <gmanuch at caltech.edu>
> To: <mitgcm-support at mitgcm.org>
> Subject: Re: [MITgcm-support] sea ice volume conservation (Martin
> Losch)
> Message-ID: <57C072DF.9090104 at caltech.edu>
> Content-Type: text/plain; charset="windows-1252"; format=flowed
>  
> Hi Martin,
>  
> This indeed solved my problem. There is still a decreasing trend in 
> total ice volume, but it is very small ~0.001% per 10 days so shouldn't 
> be an issue for my analysis.
>  
> Thanks for your help,
> Georgy
>  
>  
> On 08/26/2016 09:00 AM, mitgcm-support-request at mitgcm.org wrote:
> > Send MITgcm-support mailing list submissions to
> > mitgcm-support at mitgcm.org
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> > http://mitgcm.org/mailman/listinfo/mitgcm-support
> > or, via email, send a message with subject or body 'help' to
> > mitgcm-support-request at mitgcm.org
> >
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> > When replying, please edit your Subject line so it is more specific
> > than "Re: Contents of MITgcm-support digest..."
> >
> >
> > Today's Topics:
> >
> >     1. Re: sea ice volume conservation (Martin Losch)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Fri, 26 Aug 2016 09:26:42 +0200
> > From: Martin Losch <martin.losch at awi.de>
> > To: MITgcm Support <mitgcm-support at mitgcm.org>
> > Subject: Re: [MITgcm-support] sea ice volume conservation
> > Message-ID: <C8F1406A-20F0-4362-A203-14B57FBD40BB at awi.de>
> > Content-Type: text/plain; charset="utf-8"
> >
> > HI Gregory,
> >
> > HEFF is already the seaice volume per grid cell area (in m), i.e. (mean ice thickness of ice covered area) * AREA.
> > Compared to many other models that I know HEFF is a misleading name for the variable (effective thickness is often used for HEFF/AREA, i.e. the mean thickness of the ice covered area, so the total opposite of what it means in the MITgcm), but this has historical reasons, I guess. I think the all models based on Bill Hibler?s original code use this variable name.
> >
> > So volume in m^3 is HEFF*RAC (RAC is the grid cell area). See if that solves your problem.
> >
> > M.
> >
> >> On 25 Aug 2016, at 23:04, Georgy Manucharayan <gmanuch at caltech.edu> wrote:
> >>
> >> Hi all,
> >>
> >> I am running MITGCM with the sea ice package in a configuration that has thermodynamics turned off (i.e. using #define DISABLE_SEAICE_GROWTH in CPP_OPTIONS.h). The domain is closed. While the sea  ice is being advected by the ocean currents only, its total volume (diagnosed as HEFF*AREA) is not conserved. In fact, the volume is quickly decreasing (by ~20% within the first few days). This is problematic for my analysis.
> >>
> >> I have confirmed through diagnostics that the thickness changes due to ice-ocean and atm-ice fluxes are indeed absent (i.e. 'SIatmQnt','SIatmFW','SIfwSubl','SIdHbOCN','SIdHbATC' are all zeros). Surface temperature of the ocean also does not change, implying that the ice is not melting. Are there any other possible fluxes that might lead to ice loss when thermodynamics is off?
> >>
> >> Can the ice volume loss be related to the numerical advection schemes that do not conserve volume when independently advecting area and thickness? I have tested SEAICEadvScheme = 77 and 7 which give nearly identical results, while scheme 2 is unstable (too much ice growth). Below are some of the relevant parameters from my data.seaice file.
> >>
> >> &SEAICE_PARM01
> >>   SEAICE_no_slip     = .TRUE.,
> >>   SEAICE_drag        = 0.001,
> >>   SEAICE_tempFrz0    = -1.96,
> >>   SEAICE_dTempFrz_dS =0,
> >>   SEAICE_multDim     = 1,
> >>   SEAICE_mcPheeTaper = 0.92,
> >> #- seaice I/O params:
> >>   SEAICEwriteState   = .TRUE.,
> >>
> >> &SEAICE_PARM03
> >>   SItrNumInUse       = 2,
> >>   SItrName(1)        = 'age',
> >>   SItrMate(1)        = 'AREA',
> >>   SItrUnit(1)        = 's',
> >>   SItrName(2)        = 'one',
> >>
> >>
> >> Any suggestions are highly appreciated,
> >> Georgy
> >>
> >> -- 
> >> Georgy Manucharyan,
> >> Stanback Postdoctoral Scholar,
> >> Environmental Science and Engineering,
> >> California Institute of Technology,
> >> MS 131-24, 1200 California Blvd,
> >> Pasadena, CA, 91125
> >>
> >> Office: L+R, Room 226; Tel: (626) 395-8715
> >> Web: http://www.its.caltech.edu/~gmanuch
> >>
> >>
> >>
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> >> MITgcm-support at mitgcm.org
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> > End of MITgcm-support Digest, Vol 158, Issue 16
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>  
> -- 
> Georgy Manucharyan,
> Stanback Postdoctoral Scholar,
> Environmental Science and Engineering,
> California Institute of Technology,
> MS 131-24, 1200 California Blvd,
> Pasadena, CA, 91125
>  
> Office: L+R, Room 226; Tel: (626) 395-8715
> Web: http://www.its.caltech.edu/~gmanuch
>  
>  
>  
>  
>  
> ------------------------------
>  
> Message: 2
> Date: Sat, 27 Aug 2016 10:52:20 +0000
> From: "Menemenlis, Dimitris (329C)" <Dimitris.Menemenlis at jpl.nasa.gov>
> To: MITgcm Support <mitgcm-support at mitgcm.org>
> Cc: "weijianfen1988 at 163.com" <weijianfen1988 at 163.com>
> Subject: Re: [MITgcm-support] Sea ice initial conditions in MITgcm
> Message-ID: <8B455B64-FCB9-4E8C-8DA7-A77D64F034E6 at jpl.nasa.gov>
> Content-Type: text/plain; charset="utf-8"
>  
> Hi Jianfen, it?s best to address MITgcm support questions to the mitgcm-support at mitgcm.org<mailto:mitgcm-support at mitgcm.org> list.
> Initial sea ice conditions for MITgcm can be obtained from many different locations
> One possibility is PIOMAS, as you suggest.
>  
> Cheers, Dimitris
>  
> On Aug 27, 2016, at 12:18 AM, weijianfen1988 at 163.com<mailto:weijianfen1988 at 163.com> wrote:
>  
>  
> Hello, Professor Menemenlis,
>  
> I am a student from Nanjing University of Information Science and Technology (NUIST), China. I am not very clear about the sea ice initial conditions (including initial sea ice concentration, thickness and velocity) in the MITgcm. Are they from the dataset of PIOMAS (Pan-Arctic Ice-Ocean Modeling and Assimilation System)? If so, is the climatology or data at a particular year used to define the sea ice initial condition? I hope you can help me about this question. Thank you very much.
>  
> Best wishes,
>  
> Jianfen Wei
> School of Marine Sciences, Nanjing University of Information Science and Technology (NUIST)
>  
>  
> ________________________________
> weijianfen1988 at 163.com<mailto:weijianfen1988 at 163.com>
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