[MITgcm-support] bottom pressure diagnostics

[Oliver Jahn]

Sorry, it is the anomaly relative to Depth*rhoConst, of course,

cvs prior to 2010-1-15:

PHIBOT = gravity*ETAN + Depth/(Depth+ETAN) * gravity * \int 
(rho/rhoConst - 1) dr

should be:

PHIBOT = gravity*ETAN + gravity * \int (rho/rhoConst - 1) dr

Oliver


On 2010-02-05 09:43, Oliver Jahn wrote:
> Hi,
>
> as far as I can tell, the surface contribution is added at the end of
> diags_phi_rlow.F. HOWEVER, prior to cvs 2010-01-15, the vertical
> integral did not take the stretching of the column with nonlinFreeSurf=4
> into account, i.e., the diagnostic computed
>
> PHIBOT = gravity*ETAN + Depth/(Depth+ETAN) * gravity * \int
> (rho/rhoConst) dr
>
> rather than
>
> PHIBOT = gravity*ETAN + gravity * \int (rho/rhoConst) dr
>
> You may want to correct for this.
>
> Oliver
>
>
> On 2010-02-05 05:22, Jean-Michel Campin wrote:
>> Hi Dimitris,
>>
>> I would assume the same thing as you.
>> I will check when I am back from vacation.
>> Cheers,
>> Jean-Michel
>>
>> On Thu, Feb 04, 2010 at 08:33:07AM -0800, Dimitris Menemenlis wrote:
>>> Jean-Michel, I will be very interested to hear your answer too.
>>>
>>> Martin, up to now, I have always assumed that PHIBOT is the bottom
>>> pressure,
>>> specifically that PHIBOT in m^2/s^2 is the anomaly relative to Depth
>>> * rhonil * g
>>> so that the absolute bottom pressure in Pa is:
>>> Depth * rhonil * g + PHIBOT * rhonil
>>>
>>> 6-hourly output of ETAN and PHIBOT is available for cube78 and cub81
>>> is available online and on skylla.
>>>
>>> Dimitris
>>>
>>> On Feb 4, 2010, at 8:00 AM, Martin Losch wrote:
>>>
>>>> Hi Jean-Michel (and Dimitris),
>>>>
>>>> we would like to cube78 or cube81 bottom pressure results. Can you
>>>> confirm that for a time series of anomalies (in time) we need both
>>>> PHIBOT and ETAN (for the linear free surface contribution):
>>>>
>>>> bottom pressure = gravity*rhoConst*ETAN + PHIBOT/rhoConst (+terms
>>>> that are constant in time)
>>>>
>>>> From looking at calc_phi_hyd I gather, that the non-linear free
>>>> surface contribution etaH is only included, when selectRstar=0,
>>>> which is not the case in cube78/81, correct? But in diags_phi_rlow,
>>>> it says in the head that phi_hyd_rlow is actually bottom pressure. I
>>>> am confused.
>>>>
>>>> Martin
>>>>
>>>>
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>>>
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