Hi. I'm trying to understand how near-surface pressure observations
are assimilated in Numerical Weather Models. Obviously it is important
to remove any variation of pressure with height before comparing model
pressure to observed pressure values. Surface pressure is often
required, since often the internal vertical coordinate in a NWM is
terrain-following normalized pressure coordinate (or some hybrid of
it). The possible solutions I can think of to compare model surface
pressure to observed near-surface pressure are;
(i) assume it is zero;
(ii) convert model surface pressure to the height of the near-surface
station;
(iii) convert observed near-surface pressure to the model surface
height;
(iv) convert both model surface pressure and observed near-surface
pressure to mean-sea level pressure.
Could you please comment. Is it right that mean-sea level pressure is
not necessarily a required field in a Numerical Weather Model?

Thanks,
Felipe.

On Apr 2, 7:03 pm, "
wrote:
(i) assume it is zero;
I meant, assume the height difference between near-surface station and
model surface is zero.

Felipe.