Re: Pressure Range Problem

Helen,

This is an NCL question, so it's more appropriately posted to ncl-talk
(which I've included).

If you have the height values for the pressure values that you want to
use, then you can copy the file
$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl to your own
directory, edit the file, and modify these lines to give them the new
pressure/height values that you want (for each psa value you add, you
must include a corresponding zsa value):

   zsa = (/ -0.3, \ ; km
             0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, \
             3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, \
             7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, \
            11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, \
            18.0, 19.0, 20.0, 25.0, 30.0, 35.0, 40.0, 45.0, \
            50.0, 60.0, 70.0, 80.0, 84.8, 87.7, 90.6, \
            93.3, 96.1, 97.5,100.4,104.9, \
           110.0,114.2,116.7,119.7/)

   psa = (/ 1050., \ ; mb (hPa)
            1013.25, 954.61, 898.76, 845.59, 795.01, 746.91, 701.21, \
            657.80, 616.60, 577.52, 540.48, 505.39, 472.17, 440.75, \
            411.05, 382.99, 356.51, 331.54, 308.00, 285.84, 264.99, \
            226.99, 193.99, 165.79, 141.70, 121.11, 103.52, 88.497, \
            75.652, 64.674, 55.293, 25.492, 11.970, 5.746, 2.871, 1.491,\
            0.798, 0.220, 0.052, 0.010, 0.00485,0.00294,0.000178, \
            0.000108, 0.0000656, 0.0000511, 0.0000310, 0.0000146, \
            0.00000691, 0.00000419, 0.00000327, 0.00000254 /)

If you don't have the height values, however, then you can just use
gsn_csm_contour to plot pressure vs longitude or latitude, which it
looks like you've already done below.

Once you change this file, you will need to load your own copy, rather
than the one in $NCARG_ROOT/lib/ncarg/nclscripts/csm.

--Mary

On Tue, 3 Jun 2008, Helen Parish wrote:

> I am unable to do a standard plot (of e.g. pressure vs. latitude, pressure
> vs. longitude) because the software forces a standard range of pressures
> which you are not allowed to stray outside of. I want to plot results within
> the pressure range of around 92 bar to 0.00003 bar. I may at some point also
> want to plot as a function of height, although I only have an approximate
> idea of heights corresponding to a given pressure. I may well want to plot as
> a function of z/H as well as pressure.
>
> What I need is a simple way to modify and customize the preset pressure
> range. I believe this pressure range is set in "gsn_csm_pres_hgt", which
> makes use of "gsn_csm.ncl". I am not sure how or if I can modify this
> pressure range in my code.
>
> Below is a copy of the code which does not work as it stands right now. Can
> anyone tell me how to do this ?.
>
> Thanks,
> Helen.
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> begin
> ; input file
> diri = "./"
> fili = "rayleigh4a.cam2.h0.0009-01-04-00000.nc"
> fi = addfile (diri+fili, "r")
> ; output file
> diro = "./"
> filo = "helen.nc"
> system ("/bin/rm -f "+diro+filo) ; remove any pre-exist file
> fo = addfile (diro+filo, "c")
> ; add any file attributes
> fo_at_title = fi_at_title + ": Selected Variables at pressure levels"
> fo_at_history = systemfunc ("date")
> fo_at_source = fi_at_source
> fo_at_case = fi_at_case
> fo_at_Conventions = fi_at_Conventions
>
> Var = (/ "T" , "Q", "U", "V"/) ; select variable to be interpolated.
> nVar = dimsizes (Var)
> ; desired output levels
> lev_p = (/ 91500., 90000., 87500., 80000., 67500., 50000., 30000., 25000.,
> 18000., 10000., 8500., 7000., 4000., 3750., 3000., 2000., 1750., 1200., 600.,
> 200., 100., 30., 10., 4., 1.5, 0.5, 0.03 /)
> lev_p!0 = "lev_p" ; variable and dimension name the same
> lev_p&lev_p = lev_p ; create coordinate variable
> lev_p_at_long_name = "pressure" ; attach some attributes
> lev_p_at_units = "hPa"
> lev_p_at_positive = "down"
>
> hyam = fi->hyam ; read hybrid info
> hybm = fi->hybm
> PS = fi->PS
> P0mb = 0.01*fi->P0
>
> do n=0,nVar-1 ; loop over the variables
> X = fi->$Var(n)$
> Xp = vinth2p (X, hyam, hybm, lev_p ,PS, 1, P0mb, 2, True)
> copy_VarAtts(X, Xp)
> fo->$Var(n)$ = Xp ; write to netCDF file
> print (Var(n)+": interpolated and written to netCDF")
> end do
>
> end
> ;***********************
> ; zonal.ncl
> ;***********************
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> ;***********************
> begin
> f = addfile ("helen.nc","r")
> print(f)
> u = f->U
> printVarSummary( u )
>
> dimu = dimsizes( u )
> ntim = dimu(0)
> klvl = dimu(1)
> nlon = dimu(2)
> mlon = dimu(3)
> ;***********************
> ; Create Plot
> ;***********************
> wks = gsn_open_wks ("x11", "h_lat" ) ; open workstation
> gsn_define_colormap(wks,"rainbow") ; choose colormap
>
> res = True
> res_at_cnFillOn = True
> res_at_lbLabelAutoStride = True
> res_at_gsnMaximize = True ; if [ps, eps, pdf] make large
> res_at_gsnSpreadColors = True ; span color map
>
> do nt=0,ntim-1
>
> res_at_gsnCenterString = "t="+u&time(nt)
> plot = gsn_csm_pres_hgt(wks, u(nt,:,:,0), res ) ; (lev,lat)
>
> res_at_trYReverse = True
> plot = gsn_csm_contour (wks, u(nt,:,:,0), res ) ; (lev,lat)
> plot = gsn_csm_contour (wks, u(nt,:,0,:), res ) ; (lev,lon)
>
> kl = 5
> res_at_mpFillOn = False
> res_at_mpGridAndLimbOn = True
> res_at_mpGridLineDashPattern = 2
> res_at_mpOutlineBoundarySets = "NoBoundaries"
> res_at_mpCenterLonF = 180.
> res_at_gsnCenterString = res_at_gsnCenterString+" p="+u&lev_p(kl)
> plot = gsn_csm_contour_map_ce (wks, u(nt,kl,:,:), res )
>
> end do
>
> end
>
>
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Received on Tue Jun 03 2008 - 11:41:17 MDT