Hello Heiko,
> > fog_area_fraction:
> >
> > fog means visibility in air < 1000m due to humidity or water
> > droplets. "X_area_fraction" means the fraction of horizontal area
> > occupied by X.
I think that it's fine, but could you confirm the "humidity" part of
your definition? It sounds a little odd to me since water vapour is
invisible, although I appreciate that the relative humidity is often
very high when fog forms. How about:
"Fog means near-surface cloud which reduces the visibility in air to <
1000m. "X_area_fraction" means the fraction of horizontal area
occupied by X."
where "near-surface cloud" is meant to indicate, in some way, that the
cloud is, er, near the surface (or in the boundary layer; or ...). But
I'm not sure about that bit of wording, at all.
I know that some models output fog fraction diagnostics at 1.5m (or
2m) above the surface, but I don't know if that is in any way
standardized in all models or observed datasets.
I'm not a fog expert, so I hope that these points aren't way off the
mark.
All the best,
David
--
David Hassell
National Centre for Atmospheric Science (NCAS)
Department of Meteorology, University of Reading,
Earley Gate, PO Box 243,
Reading RG6 6BB, U.K.
Tel : +44 118 3785613
E-mail: d.c.hassell at reading.ac.uk
Received on Tue Aug 06 2013 - 11:05:08 BST
