[MITgcm-support] Potential temperature
Sergio Jaramillo
sju at eos.ubc.ca
Thu Jun 3 12:47:03 EDT 2004
Martin,
That is exactly what I have, then:
tRef(z)=(rho_reference-rhoNil)/(tAlpha*rhoNil)
where, with 32 levels, if I use (from measurements in a rotating tank):
rho_reference (kg/m^3)= [1004.3, 1008.7, 1012.8, 1016.3,
1019.2, 1021.3, ...
1022.8, 1024.0, 1025.2, 1026.6, 1028.0, 1029.1, ...
1030.3, 1031.7, 1032.9, 1033.8, 1034.8, 1036.1, ...
1037.4, 1038.4, 1039.3, 1040.1, 1041.1, 1042.1, ...
1043.1, 1043.9, 1044.7, 1045.3, 1046.1, 1047.1, ...
1048.6, 1050.6];
rhoNil =mean(rho);
tAlpha=2e-4;
I get :
tRef = [-142.678, -121.397, -101.567, -84.6392, -70.6133, ...
-60.4566, -53.2018, -47.3979, -41.5941, -34.823, ...
-28.0518, -22.7317, -16.9278, -10.1567, -4.35287, ...
0, 4.83653, 11.124, 17.4115, 22.248, ...
26.6009, 30.4701, 35.3066, 40.1432, 44.9797, ...
48.8489, 52.7181, 55.62, 59.4893, 64.3258, ...
71.5806, 81.2536];
with these values for tRef(z), the model breaks, so what I am doing is
increasing arbitrarily tAlpha to 2e-3, and then the model runs fine. But
I was wondering if there was a way of doing it without increasing
tAlpha. Is the measured density (rho_reference above) ok for this
calculation? should I change something in it?
Thanks again,
Sergio
>Message: 3
>Date: Thu, 3 Jun 2004 09:26:06 +0200
>From: Martin Losch <mlosch at awi-bremerhaven.de>
>Subject: Re: [MITgcm-support] Potential temperature
>To: mitgcm-support at mitgcm.org
>Message-ID: <46A87684-B52F-11D8-8770-000A9591B488 at awi-bremerhaven.de>
>Content-Type: text/plain; charset=US-ASCII; format=flowed
>
>Not quite sure, what you mean, but
>rho=rhoNil*(1-tAlpha*(theta(z)-tRef(z)) + sBeta*(salt(z)-sRef(z)))
>is the linear eos. rhoNil is a constant. So if sBeta=0 then
>rhoNil*(1+tAlpha*tRef(z)) is your reference density.
>
>Martin
>
>On Wednesday, June 2, 2004, at 07:48 PM, Sergio Jaramillo wrote:
>
>
>
>>Dear MITgcm support,
>>
>>I have what may be a dumb question but it is one of the few things
>>that I want to verify before send it to Martin Losch who kindly
>>offered a detailed check.
>>
>>Question: If I have a density profile, constant salinity, and I want
>>to use a linear equation of state, how can I get the potential
>>temperature profile (tRef in data file) that matches the density to
>>use it as an input for the model?
>>
>>I am not confident with the way I am doing this now, and I appreciate
>>any help.
>>
>>Many thanks,
>>
>>Sergio Jaramillo
>>UBC
>>
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>>MITgcm-support mailing list
>>MITgcm-support at mitgcm.org
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>>
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