[MITgcm-support] tracer concentration

[David Munday]

Hi Angela,

Are you using the CD scheme? I noticed problems with passive tracer conservation, even with a flux limited scheme, when I used the CD scheme with the vector invariant form of the momentum equations. I can't remember the details, but I think this is an established problem (?) with tracers in general with this combination (I didn't have a problem with T & S because I was using restoring conditions).

Best wishes,

Dave

On 24 Feb 2011, at 22:44, Angela Marie Zalucha wrote:

> The tracers are passive.
> 
> There is no change in atmospheric mass with time.
> 
> There are no sources and sinks of tracers.
> 
> 
>  Angela
> 
> 
> 
> On Thu, 24 Feb 2011, Yuan Lian wrote:
> 
>> Are you running the ptracers package with passive tracers? Is any change in the atmospheric mass if
>> the tracer is passive? Do you have any sink or source of tracers? I don't see much problems
>> with most of the advection schemes for passive tracers, though some deviation exists but should be
>> smaller than 0.1% in most cases.
>> 
>> If the total atmospheric mass is changing, make sure the tracer mixing ratio is updated properly
>> (i.e, scaling the mixing ratio in columns).This should also work if the tracer is semi-passive, i.e., the
>> mass loading of tracer is considered in the model.
>> 
>> If you have sink and source of tracers, make sure they are self-consistent. Or if you are updating tracer
>> tendencies in physics grid, make sure the schemes are conservative.
>> 
>> Cheers,
>> Yuan
>> 
>> 
>> 
>> On 2/24/11 1:17 PM, Angela Marie Zalucha wrote:
>>> Hello, I am working with the ptracers package.  I am finding that after running for about 5 days, the tracers are not conserving mass at all--the increase in mass is about 50%, which is pretty significant.  I am using advection scheme 81 (I have tried 7, 30, 33, 77, 80, but with similar results).  Is this typical?  Are there any ways around this?
>>> Thanks,
>>>  Angela
>>> _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
>>> Angela Zalucha, Ph.D.
>>> Postdoctoral Associate
>>> Department of Earth, Atmospheric,
>>>  and Planetary Sciences
>>> Massachusetts Institute of Technology
>>> Office located at Southwest Research Institute
>>> 1050 Walnut Street, Suite 300
>>> Boulder, CO 80302
>>> USA
>>> (720) 208-7211
>>> http://web.mit.edu/azalucha/www/index.html
>>> _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
>>> _______________________________________________
>>> MITgcm-support mailing list
>>> MITgcm-support at mitgcm.org
>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>> 
>> 
>> _______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>> 
> 
> _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
> Angela Zalucha, Ph.D.
> Postdoctoral Associate
> Department of Earth, Atmospheric,
>  and Planetary Sciences
> Massachusetts Institute of Technology
> 
> Office located at Southwest Research Institute
> 1050 Walnut Street, Suite 300
> Boulder, CO 80302
> USA
> (720) 208-7211
> 
> 
> http://web.mit.edu/azalucha/www/index.html
> _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
> 
> 
> 
> 
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support

*****************************************************************************

Dr. David R. Munday
University of Oxford
Atmospheric, Oceanic, and Planetary Physics
Clarendon Laboratory
Parks Road
Oxford
OX1 3PU
U.K.                 01865 272 925

*****************************************************************************

"But I, being poor, have only my dreams;
I have spread my dreams under your feet;
Tread softly because you tread on my dreams."
     - W.B. Yeats, He Wishes for the Cloths of Heaven -

*****************************************************************************