[RegCNET] About idirect in RegCM3 -aerosol

[Solmon Fabien]

Hi Prodromos !

idirect=1 = aerosol without climatic feedback BUT radiative forcing
calculated .
the radiative forcing is calculated on line , passing 2 times in the clear
sky radiative transfer routine
idirect=2 allows the aerosl to feedback on the radiative tendencies ;
in this case the radiative forcing calculated  accounts implicitely for
atmosphere feedback  ( so it is not a radiative forcing stricto sensu )
idirect = 0 : no radiative forcing is calculated so you save a bit of time
if you just want to do transport of aerosols ; for example if a French
nuclear power plant explodes , you are first more concerned by the
transport than the climatic impact ..

the TOA radiative forcing is calculated  by the difference of top of
atmosphere net clear sky SW flux ( which is equivqlent to mqke the
difference between outgoing SW flux) between no and with aerosol .. same
for the surface forcing ...


climate impact = idirect =2 - idirect=1 or idirect=0 ...

hope it helps

cheers

fabien


> Dear colleagues
>
> I would be glad if someone would give me a few clarifications for idirect.
> When idirect=0 then there is no climate feedback from aeresols
> and when idirect=2 then we have climate feeback from aeresols.
> What about when idirect=1? What is the difference between idirect 1 and 2.
> Is it like that if someone wants to look the climate feedback from
> aerosols (e.g. on surface Temperature) then should take the diffrence of a
> simulation with idirect=2 from the simulation with idirect=1.
>
> Also I have another question for the radiative forcing.
> In CHEM output files there are the parameters acstoarf0 for TOA (Top of
> the Atmosphere) radiative forcing and acstsrrf0 for SRF (surface)
> radiative forcing.
> In what sense are these two parameters defined?
>
> I look forward for your feedback
>
> With kind regards
> Prodromos
>
> --
> ****************************************************
> Dr. Prodromos Zanis
> Centre for Atmospheric Physics and Climatology
> Academy of Athens
> 3rd September 131, Athens 11251, Greece
> Tel. +30 210 8832048
> Fax: +30 210 8832048
> e-mail: pzanis at geol.uoa.gr
> Web address: http://users.auth.gr/~zanis/
> *****************************************************
>
>
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