[MITgcm-support] Track freshwater flow from sea ice melting

[Yilang Xu]

Thank you Martin! 

Yes I have been staring at tmpscal1 in line 2375 for a while, and trying to figure out the meaning of each term in tmpscal1. If all terms in it are related to sea ice freshwater flux, then it makes sense to save them to one variable and pass it to ptracers. 
Initially I thought I could eliminate EVAP, PRECIP, and RUNOFF in EmPmR, and only keep the <0 part to get the sea ice melting. But then I realize that EVAP and PRECIP shall be weighted by sea ice area, and the overall calculation is not intuitive. Glad that the freshwater flux from sea ice has already been combined. 

Cheers,
Yilang 

On 5/19/22, 13:37:53, "MITgcm-support on behalf of Martin Losch" <mitgcm-support-bounces at mitgcm.org on behalf of Martin.Losch at awi.de> wrote:

    Hi Yilang,

    if you are using seaice_growth (default if you use the pkg/seaice), then this is the only place where sea ice modifies the freshwater flux into the ocean.

    The freshwater flux due to ice is (in mass units)

         &         + tmpscal1*convertHI2PRECIP
         &         )*rhoConstFresh

    where tmscal1 is the sum of all terms starting in line 2357 is seaice_growth.F
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    Now, some of these contributions are freezing, some are melting, so I would probably save this tmpscal1 in a new 2D field that I pass to pkg/ptracers/ptracers_forcing_surf.F, and you could add this flux only if the sign means melting (i.e. tmpscal1<0).

    Martin

    > On 19. May 2022, at 18:29, Yilang Xu <yxu at whoi.edu> wrote:
    > 
    > Hi all, 
    >  
    > Just follow up on my previous question as I have proceeded from there. The linkage between EmPmR and passive tracer concentration can be formed by modifying pkg/ptracers/ptracers_forcing_surf.F and prescribing PTRACERS_EvPrRn in data.ptracers.
    > However, EmPmR is the net freshwater flux, and I need only the contribution of sea ice to freshwater flux. So I look into pkg/seaice/seaice_growth.F, and find that EmPmR is modified there by several terms related to sea ice.
    >  
    > My question is, is pkg/seaice/seaice_growth.F the only place where EmPmR gets modified and later transferred to pkg/ptracers/ptracers_forcing_surf.F? if that is the case, I can take some variables in seaice_growth.F and use them in ptracers_forcing_surf.F.
    >  
    > Thanks,
    > Yilang 
    >  
    >  
    > From: Yilang Xu <yxu at whoi.edu>
    > Date: Friday, April 8, 2022 at 13:23:20
    > To: "MITgcm-support at mitgcm.org" <MITgcm-support at mitgcm.org>
    > Cc: Yilang Xu <yxu at whoi.edu>
    > Subject: Track freshwater flow from sea ice melting
    >  
    > Dear MITgcm community, 
    >  
    > I am wondering if there is a way to track the trajectory of the freshwater flow exclusively from sea ice melting. Currently the model outputs net surface freshwater flux (oceFWflx) using diagnostics. But I want to track only the contribution from sea ice melting, and try to link it with ptracers package to add a surface source of passive tracers. Appreciate it if anyone could help to point out which sea ice variable to look into.
    >  
    > Thanks,
    > Yilang 
    >  
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