Global Carbon Cycle Example

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bloodyr
Junior Member
Posts: 2
Joined: Mon May 14, 2018 3:35 pm
Vensim version: PLE

Global Carbon Cycle Example

Post by bloodyr »

Hi, Anyone have any global carbon cycle examples for vensim. I cant set my units and will be crazy soon :) So, I need working examples and i ll be pleasure. I searched forum but link dead or topic was locked. Thanks all
Administrator
Super Administrator
Posts: 4573
Joined: Wed Mar 05, 2003 3:10 am

Re: Global Carbon Cycle Example

Post by Administrator »

If you want to upload your model, we might be able to help solve the units problem.
Advice to posters seeking help (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
http://www.bbc.co.uk/news/magazine-27509559
tomfid
Administrator
Posts: 3806
Joined: Wed May 24, 2006 4:54 am

Re: Global Carbon Cycle Example

Post by tomfid »

http://metasd.com/2014/07/free/
http://metasd.com/2010/06/dice/

Generally, atmospheric CO2 is measured in GtC (gigatons carbon), with the corresponding emissions and uptake flows in GtC/year. But you'll often find emissions in GtCO2 terms - a ton of CO2 is 44/12 tons of C.
bloodyr
Junior Member
Posts: 2
Joined: Mon May 14, 2018 3:35 pm
Vensim version: PLE

Re: Global Carbon Cycle Example

Post by bloodyr »

I found this on internet. But it gives error when i check units. I cant fix this. And i really dont know what is the wrong... If you help, i ll be pleasure. Thank you.
Attachments
Carboncycle.mdl
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tomfid
Administrator
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Joined: Wed May 24, 2006 4:54 am

Re: Global Carbon Cycle Example

Post by tomfid »

This model has a lot of parameters embedded as numbers in equations. For example:

Code: Select all

***********************************************
Error in units for the following equation:
CO2 absorption  = 
        92
             * ( Atmosphere 
                  / 750) 
CO2 absorption  --> Gt/yr
Atmosphere  --> Gt

Analysis of units error:
Right hand and left hand units do not match
CO2 absorption 
Has Units: Gt/yr
92
     * ( Atmosphere 
          / 750) 
Has Units: Gt

***********************************************
That's bad practice. What does 92 mean, and what are its units?

All parameters should be separate variables with assigned units, so they're properly dimensioned and exposed to sensitivity testing.
tomfid
Administrator
Posts: 3806
Joined: Wed May 24, 2006 4:54 am

Re: Global Carbon Cycle Example

Post by tomfid »

If you post your error, we might be able to help. Also, the models I posted should be error-free.
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