wind_4.ncl script

From: Sang-ki Lee (Sang-ki.Lee AT XXXXXX)
Date: Wed Apr 21 2004 - 16:39:48 MDT


Hello.

I am a ferret user, but I just started using NCL from today because
I need to compute the velocity potential from the monthly ncep
reanalysis. I just did that using "wind_4.ncl" (which can be
downloaded from the ncl webpage). The wind_4.ncl script uses
the follwing four ncl routines:

uv2dvG(u,v) for divergence
ilapsG(div,0) for velocity potential
dv2uvg(div,ud,vd) divergent wind

But, the computed velocity potential is very different from that
provided from CDC (velocity potential is included if you download
ncep reanalysis from CDC). Furthermore, the divergent wind is not
perpendicular to the velocity potential.

Does it mean that the velocity potential computaion using NCL
is not reliable? Or am I doing something wrong? Only modification
I made to wind_4.ncl is the file reading statement (I am reading
grib data).

Thank you.

Sang-ki

-- 
----------------------------------------------------------------------
Sang-ki Lee
RSMAS/CIMAS
University of Miami
4600 Rickenbacker Causeway
Miami, FL 33149 USA
Tel) 305-361-4521
Fax) 305-361-4412
E-mail) sang-ki.lee AT noaa.gov
----------------------------------------------------------------------
Mailing-address:
Sang-ki Lee
AOML/PHOD
4301 Rickenbacker Causeway
Miami, FL, 33149 USA
----------------------------------------------------------------------

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