Chun-Ji,
For interpolations below the PS (surface pressure), it is often recommended that
you use the function vinth2p_ecmwf, which does a much better job than the
regular vinth2p. vinth2p_ecmwf does require 2 additional fields, the bottom
layer's surface temperature and PHIS, but the results from the function are much
more believable. See the documentation for further questions regarding the
function:
http://ngwww.ucar.edu/ngdoc/ng/ref/ncl/functions/vinth2p.html
Keeping in mind that all values interpolated below the PS are bogus values, you
can always set the kxtrp option in both vinth2p and vinth2p_ecmwf to False,
thereby causing the function to not return any interpolated values below the PS.
Adam
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>Subject: interpolation from hybrid to pressure
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Hi,
I will a regional climate model using A1 scenario which is a simulated
result from CSM 1.2 from July 1987 over Asia. On pre-process, a problem
happened. To transform 3-D variable such as U, V, T, RH and GH into
pressure coordinate, the interpolation from GCM coordinate (hybrid
coordinate) to RCM coordinate (pressure coordinate) should be handled in
a pre-process to make a initial condition as well as boundary condition.
I used a vinth2p internal function in NCL program as vertical
interpolation method. It is provided to use a CSM history file. In
particular, the interpolated problem is much intensified over Tibet
Plateau.
I attached figures which were results before convert to pressure and
after convert to pressure.
For example,
Pnew =
(/1000.,925.,850.,700.,600.,500.,400.,300.,250.,200.,150.,100.,70./)
P0mb=1000.
Tnew = vinth2p(T,hyam,hybm,pnew,PS,2,P0mb,1,True)
Please point out my mistakes.
Best regards,
Chun-Ji Kim
-------------------------------------------------------------
Adam Phillips email: asphilli AT ucar.edu
Climate and Global Dynamics Division tel: (303) 497-1726
National Center for Atmospheric Research fax: (303) 497-1333
P.O. Box 3000
Boulder, CO 80307-3000 http://www.cgd.ucar.edu/~asphilli
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