[MITgcm-support] tracer concentration

[Jean-Michel Campin]

Hi Angela,

MITgcm conserve passive tracer (even with CD-scheme on), i.e.,
the total content follows the integrated source-sink, and stay 
constent if no source-sink.
Could you give more details about your problem/set-up (otherwise, 
will not be able to provide a usefull advise).

Thanks,
Jean-Michel

On Thu, Feb 24, 2011 at 05:44:28PM -0500, 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
>>> _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
>>>
>>>
>>>
>>>
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>>
>>
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>
> _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
> 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
> _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
>
>
>
>
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