Output unit of backward simulation for stratospheric ozone tracking

[sulinust]

As there are three output unit for backward simulation, s, s kg/m3 and s m3/kg, how can I get mixing ratio such as ppb and ppb, in backward simulation for stratospheric ozone tracking?

[jbrioude]

In backward simulation, it wouldn't make sense to output a mixing ratio.

To better grasp the concept of backtrajectories, I suggest you to read the paper by Seibert and Frank (2004) doi:10.5194/acp-4-51-2004

To get a mixing ratio using backtrajectories, you would need to fold your FLEXPART output (with a unit of sm^{3/kg) with a flux of a tracer (in kg/m3/s).}

[sulinust]

Replying to jbrioude:

Thanks for the reply, how about the stratospheric ozone option (mdomainfill=2)? Isn't it supposed to output the mixing ratio of stratospheric ozone at a receptor? I have seen results of stratospheric ozone tracking in different paper, they are all in unit of ppb or ppt...

[pesei]

... this would be a typical question for the mailing list (see RegisteredUser), instead of ticket system.

A short version of what you find in our 2004 paper: in backward mode, we cannot have a source, let material disperse, and then obtain a concentration or mixing ratio. We can only calculate a source-receptor sensitivity relationship.

The question about domain-filling simulations in backward mode is interesting, I have not yet analysed that in detail. However, what could be a reason for doing a domain-filling run in backward instead of forward mode? Usually, we do backward runs if we have only few receptors but many sources. However, in a domain-filling run there are no sources.