[RegCNET] Aerosol Optical Depth in dust simulation

[Carolina Cavazos Guerra]

Dear Fabien, 

Thank you very much for your reply. Its very useful. Indeed I got the OPT file containing the following optical parameters as:

AOD as the integrated Aerosol optical thickness in the visible band and 
aext8 as aerosol optical depth

From my previous understanding the aext8 was equivalent the optical depth per layer in the visible band too. Then by summing all aext8 I would expect will give the same values as the the aod variable. 

Although patter is somehow similar as expected, values for the integrated aext8 are very small by several orders of magnitude.

I would appreciate any clarification about how these values work.

Best Regards

Carolina

 


Dr. Carolina Cavazos-Guerra
Postdoctoral Research Associate
Department of Geography
University of Sussex
Room 142 Chichester I Building
Falmer, Brighton, BN1 9QJ, UK
Tel: +44 (0) 127387 3357


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________________________________________
From: regcnet-bounces at lists.ictp.it [regcnet-bounces at lists.ictp.it] on behalf of Solmon Fabien [fsolmon at ictp.it]
Sent: 21 May 2013 13:58
To: regcnet at lists.ictp.it
Subject: Re: [RegCNET] Aerosol Optical Depth in dust simulation

Hello Carolina

To reply to your different points:

On 05/21/2013 01:07 PM, Carolina Cavazos Guerra wrote:
> Dear RegCM users.
>
> I used RegCM3 some time ago and now I'm trying to use RegCM4.3 again for some dust simulations over Africa.
>
> I managed to run some dust simulations using the new chem following the recommended steps in the users guide and posts made recently on the RegCNET pages. First, I copied over the namelist from one of the examples for dust in the Testing folder contained in the last RegCM4.3 version. My chemparam stanza looks as follows
>
> &chemparam
>   idirect   =  2,
>   chemsimtype = 'DUST   ',
>   ichsolver = 1,
>   ichdustemd = 2,
>   ichsursrc = 1,
>   ichcumtra = 1,
>   ichdrdepo = 1,
>   ichremlsc = 1,
>   ichremcvc = 1,
>   ichebdy=0,
>   ichdiag=0,
>   /
>
> As a first instance I am not activating the ichebdy option to generate dust boundary conditions and I wonder how much difference would this make for short runs if just enough time for spin-up is given.
  It really depend on your domain. If you have a big domain that
encompass most of the sources , it is not a big issue.
  If you have a small domain and for an intense event , it should not be
a big issue ( unless you cut the bodele , which you probably do not)
If you have a small domain with large sources just outside the
boundaries and you run climate. That mi8ght matters a lot.

> I successfully did run a short simulation and got the correspondent diagnostics in the files generated for each tracer, DUST_1, DUST_2, DUST_3 and DUST_4. However AOD is nowhere to be seen.
You need to activate ifopt = .true. in the outparam stanza
( we should get rid of this option as soon as aer option is activated)

> Now, quoting from the users guide: The chemistry outputs consist of one netCDF file per tracer named explicitely and containing concentration fields + different diagnostics, and one netCDF file giving the optical properties of the total aerosol mixture
> i.e. aerosol optical depth and radiative forcing.
cf prevois comment
> I was having a look to the RAD files which indeed contains diagnostics for SW and LW radiation but still can not find AOD. I also activated the ichdiag=1 which generate extra diagnosis in case I was missing something and nothing.

ichdiag gives the tracer tendency diagnostics (source, dep, adv etc )
it makes also big file)
> Am I missing missing something in the configuration? Any help will be very welcome.

there is also eventually the possibility to directly tune linearly the
emission flux with via  rdstemfac ( by default it is 1).
As you did, I encourage to use

ichdustemd = 2 over Africa


> Best regards
>
> Carolina
>
> P.S. Just a last comment aside from a very personal point of view, although there seem to be some improvements in this new version RegCM4, it seems to be much less user friendly that it use to be and its becoming more and more confusing in terms of configuration.


Fabien



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Fabien Solmon
Research Scientist
+39 040 2240206 (office) | Earth System Physics
+39 040 2240449 (fax)    | ICTP (UNESCO-IAEA)
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