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PostPosted: Tue Apr 22, 2014 5:14 pm 
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Joined: Tue Apr 22, 2014 5:11 pm
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I am Prasanta Kumar Bal, Scientist Centre for Climate Change and Adaptation research , Anna University, Chennai, India.

I have completed the PRECIS model runs for AR4 simulations by using HadCM3Q LBC data.

I need some clarifications to analyze SO2 data.

I have collected observation data for the Chennai city, Tamil Nadu which is in mg/m3 (observation data is ambient so2 data i.e after the emission, how much so2 is remained in the atmosphere. This is not the stack emission data from the industry )

so which parameter I need to select from the PRECIS output which are listed as below to validate with the observational data? The output is in kg/m2/sec. How to convert kg/m2/sec to mg/m3?

Stash code Description Units

58 sulpher dioxide emmisions kg/m2/sec

101 so2 mass mixing ratio kg/kg

121 natural so2 emissions kg/m2/sec

126 high level so2 emissions kg/m2/sec

Please can you provide me the description about the each stash code.


Regards

Prasanta Kumar Bal


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PostPosted: Tue Apr 22, 2014 5:17 pm 
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Joined: Thu Feb 06, 2014 12:29 pm
Posts: 118
Dear Prasanta,
I relay the response from Simon, who is quoting another colleague at the Met Office:

Quote:
Given what the observational data are, it looks like STASH code 00-101 ("SO2 MASS MIXING RATIO AFTER TSTEP") from the lowest model layer would be the obvious thing to compare against.

Notes:
(1) As the name says, this is mass mixing ratio, so would need to be multiplied by air density to convert to kg/m3 (and then to mg/m3).

(2) As with all sulphur-cycle variables, this one is mass mixing ratio of S-in-SO2, i.e. only the mass of the sulphur atom is considered. If the observations are of the mass of SO2 (which is likely), then as well as multiplying by air density, 00-101 will need to be multplied by the ratio of the atomic weights of SO2 and S (which, conveniently enough, in this case is just a multiplication by 2: S=32, O=16, so SO2/S = (32+16+16)/32 = 2)



Thank you,
David on behalf of Simon T and the PRECIS team


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