[MITgcm-support] How to force river runoff data in a regional domain

[kunal madkaiker]

Thank you Stefano for the detailed explanation. This helps a lot.

Regards,
Kunal


On Thu, Jul 29, 2021 at 7:51 PM Stefano Querin <squerin at inogs.it> wrote:

> Hi Kunal,
>
> On 29 Jul 2021, at 14:20:40, kunal madkaiker <kunal.madkaiker02 at gmail.com>
> wrote:
>
> Thank you all for your suggestions.
>
> Incase I go with option 3, my question is, do I have to select grid points
> for runoff in X or Y (1D) direction, or can they be 2D (XZ or YZ)?
>
>
> If you choose option 3 with OBCS, you simply have to produce 2D OBCS
> "slices". In your specific case, if you use northern OB, set a 2D (XZ)
> slice with all zeros, except in the x-coords where you have the sources of
> your rivers. If your riverbeds are (for example) 4 cells deep, set in your
> northern OBC file: V(x-coord,1:4)=V_prescribed (the same for T and S). U=0.
> V_prescribed (entering from the north, hence negative) [m/s] times
> delX(x-coord) [m] times sum(delZ(1:4)) [m] is your prescribed flow rate.
>
> If 2D, then how can I force them through data.obcs.
>
>
> River runoff file (series of different slices, if they vary in time) must
> be treated the same way as the other OBCS files (W, S, E, in your case).
> In data.obcs you have to specify (OB_Jnorth) the x and y coordinates of
> your river sources (upstream end of each riverbed).
> More details here:
> https://mitgcm.readthedocs.io/en/latest/phys_pkgs/obcs.html#tab-phys-pkg-obcs-runtime-flags
>
> Anyway, as correctly suggested by Dimitris and Stanislav, it is better to
> start in a simple way first, and then try more complex approaches, if
> things don't seem to work properly...
>
> Kind regards,
>
> SQ
>
>
> Regards,
> Kunal
>
> On Thu, Jul 29, 2021 at 10:25 AM Stanislav Martyanov <
> martyanov.sd at gmail.com> wrote:
>
>> Hello, Kunal,
>>
>> I use option #1 (#define ALLOW_RUNOFF, and corresponding settings in
>> data.ext) for the Kara Sea regional domain, and it works fine. The spatial
>> resolution is also rather high: O(1 km) in horizontal and 2m in vertical.
>> Simulation of thermohaline structure near river estuaries and getting
>> realistic river plumes (at least as much as the resolution allows) also
>> sometimes requires knowing the temperature of riverine waters, which often
>> is not available. As I remember, by default MITgcm takes the local water
>> temperature as the input river water's temperature, but in reality it is
>> not always the case.
>>
>> Regards,
>> Stanislav Martyanov
>>
>> ср, 28 июл. 2021 г. в 13:10, kunal madkaiker <kunal.madkaiker02 at gmail.com
>> >:
>>
>>> Dear MITgcm users,
>>>
>>> I am doing regional simulations in the Northern Indian Ocean.
>>> Stratification in Bay of Bengal is controlled by salinity and freshwater
>>> flux since many rivers like Ganges, Brahmaputra empty into this basin.
>>>
>>> I am not able to properly simulate my temp, salinity and currents into
>>> the Head bay region of BoB as I am unable to produce an equatorward flow in
>>> my domain. Freshwater increases in this region during month of JJAS due to
>>> melting of Himalayan glaciers.
>>>
>>> I have gone through previously asked similar questions about river
>>> runoff and came to know the following possibilities:
>>>
>>> 1. To feed at surface through data.exf
>>>
>>> 2. Feeding a 3-D run-off input using addMassFile
>>>
>>> 3. Through OBCS/ RBCS.
>>>
>>> My domain is regional, with small dz and high spatial resolution.
>>> Please let me know which option is the best suited and reliable, since I
>>> not only want to improve my temp/ salinity but also to rectify the
>>> circulation in head bay region. I would be using Dai et al. (2009) river
>>> runoff data.
>>> All suggestions are welcome. Attaching figure of my model domain.
>>>
>>> Thanks and Regards,
>>> Kunal
>>> _______________________________________________
>>> MITgcm-support mailing list
>>> MITgcm-support at mitgcm.org
>>> http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support
>>>
>> _______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
>> http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support
>>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support
>
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20210730/52ebcdd1/attachment.html>