CO2 fluxes are in molecule/cm2/s. I don't know how to convert it into ppmv. I would be most grateful if anyone can give me some suggestions.
Vipin
The question is NOT on converting concentrations. The question is how to convert a flux to a concentration in the air. The questioner does not realize that a flux is per unit time and concentration must be defined in a volume; what exactly does he mean?
Harry ten Brink: Sir,. Thank you for your clarification. Hence the answer was inappropriate, I have removed it from the answers.
Vipin,
I have not seen your answer but it may have been the correct reply to the question Krishnapriya intended to ask!
As Harry points out, as it stands the question is how to convert a flux N cm-2 s-1 to a concentration N cm-3 which is not possible.
Krishnapriya, you need to rephrase your question or explain the problem you are trying to solve.
Harry,
that was what I had guessed. It is a pity that he deleted his post as it was probably the answer to the intended question.
Thank you all for your time and consideration.This is my main query: We have CO2 flux data in molec/cm2/s. We want to express it in terms of ppm. (My friend Mr. Bhuvan Chandra posted the same question here and he got the reply that molecule/m2/sec represents flux and ppmv is the mixing ratio and the conversion of this unit required diffusion coefficient in the context of air) Further clarification will help us very much.
You have to specify the area from which the emisson takes place and the volume in which it is emitted.
The answer requires the details and even more information, at least a minimal model of the situation. The scale and wind speed (in the least) are required in order to determine the mass transfer coefficient on an ordinary scale--this becomes the diffusivity at molecular scales. Then you look at mass transfer through a gradient (or difference in concentration over a finite distance, a finite approximation of an infinitesimal). The flux flows through this distance and there is one concentration on one side C1 and another on the other C2. Perhaps the second side is a surface. Then you need some idea of what happens at the surface, if you want to predict the concentration C1. If the surface is a trap which 'locks' up the CO2 totally, C2 could be considered as zero. If it is a water surface, there is some likelihood the water is in equilibrium with the (I presume) air. With that assumption, you can use the Henry's law constant (from the solubility at the given temperature with other effects like from common ions in the liquid) to determine the air concentration from the concentration in the liquid. A simplest expression of this is something like: Flux=K*(C1-C2), Fick's law. When you have a proper model of your situation, you will be able to estimate your concentration. But remember to check and recheck all your units and units conversions are correct--DO NOT SIMPLY THROW NUMBERS IN!--or you will only produce rubbish. I like to use unity factors (units ratios that are really only 1) that I can use as multipliers anywhere and not effect the magnitude, like (say) {12 inches/1 foot=1}.
33 inches/{}=2.75 feet If you say 'I don't want to know' there is no hope for you, and 'usung the metric system is no excuse.
Hi Mr.Scott,
Thank you for your information and sorry for the delayed reply... Sir, Could you please brief your answer?.... Because I didn't understood properly the explanation which you have given.... Actually I have the CO2 concentration in ppmv and some of the flux terms like fossil fuel, biofuel etc.. are in molecules/cm2/sec . I need to express these quantities in a common unit platform. So I decided to convert it in terms of gram Carbon. I tried my best and couldn't find any solution. So could you please tell me if there is any alternate way of expressing these quantities in a common platform.
Regards,
Krishnapriya M.
ppmv is Parts Per Million by Volume. That is the ratio of molecules of CO2 to molecules of air. So, in order to compare that with your fluxes we need to the amount of air they are mixed with.
What are you trying to do? Is it to work out the concentration of CO2 in a city such as Delphi, from the amount of CO2 being produced locally. Then you need to know the flux of air (wind) passing over the city to make that calculation.
You can only compare apples with apples, not with oranges. And you can only compare concentrations with concentrations, not with fluxes.
HTH.
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