[MITgcm-support] tracer concentration

[Yuan Lian]

Are you using rstar coordinate? You may need to reconstruct the
vertical dynamics grid because the levels do not line up with
the isobars in rstar or eta coordinates, that is, reconstructing the
vertical grid using eta, hfac and rstar and then calculating the
tracer mass from there. I am sure Jean-Michel can explain
more in details.

Yuan


On 2/24/11 2:44 PM, 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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