Re: change eta levels to pressure levels in cross-section plot with the function "gsn_csm_pres_hgt_vector"

In order to use any of the gsn_csm_pres_hgt routines, you must have data arrays that are rectilinear and contain a 1D level coordinate array.

The wrf interpolation functions you are using do not return the data on a rectilinear grid, and hence you can¡¯t use gsn_csm_pres_hgt_vector to plot it.

Again, I¡¯m going to CC wrfhelp here in case they have suggestions about how you can take cross sections of your WRF data and get back data on a rectilinear grid.

We *do* have examples of regridding WRF data to rectilinear grids, but this will not work when you have U/V data. You can see the examples at:

http://www.ncl.ucar.edu/Applications/ESMF.shtml

Search for ¡°WRF¡± on this page.

¡ªMary

On Apr 15, 2014, at 7:44 PM, »ÆСÏɶù <313695096@qq.com> wrote:

>
> Hi,all:
> I wanna to use wrfout data to draw a cross-section plot with the function "gsn_csm_pres_hgt_vector",which need the data muse be two-dimension. And the leftmost dimension must contain a one-dimensional coordinate array of pressure values, and the values must be in the correct units. the accepted units are "hpa", "hPa", "Pa", "pa", "mb", "millibars", etc.
> I checked the dimension names,dimensions and unit of the data involved,
> the first dimension name is Vertical and dimensions and sizes: [Vertical | 100] x [Horizontal | 274],I do not know how to handle it,could you gays help me out of this?
> this is my ideal picture:
> <9D586078@936EF17A.82E04D53.jpg>
> This is my script:
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
> begin
>
> ; file handling
> ;************************************************
> ; define filename
> in = addfile("/home/Huanglei/data/d03"+".nc","r") ; open netcdf file
> ;************************************************
> ; read needed variables from file
> ;************************************************
> times = wrf_user_getvar(in,"times",-1) ; get times in the file
> ntimes = dimsizes(times) ; number of times in the file
> FirstTime = True
>
> mdims = getfilevardimsizes(in,"P") ; get some dimension sizes for the file
> nd = dimsizes(mdims)
>
> ;---------------------------------------------------------------
>
> do it =3,ntimes-1,2 ; TIME LOOP
>
> print("Working on time: " + times(it) )
>
>
> tc = wrf_user_getvar(in,"tc",it) ; T in C
> v = wrf_user_getvar(in,"V",it) ; v wind
> w = wrf_user_getvar(in,"W",it) ; w wind
> z = wrf_user_getvar(in, "z",it) ; grid point height
> wa = wrf_user_unstagger(w, w@stagger)
> printVarSummary(w)
>
> printVarSummary(wa)
>
> if ( FirstTime ) then ; get height info for labels
> zmin = 0.
> zmax = max(z)/1000.
> nz = floattoint(zmax/2 + 1)
> FirstTime = False
> end if
>
> plane = new(4,float)
> plane = (/ 2,2, mdims(nd-1)-2, mdims(nd-2)-2 /)
> opts = True
> t_plane = wrf_user_intrp3d(tc,z,"v",plane,0.,opts)
> v_plane = wrf_user_intrp3d(v,z,"v",plane,0.,opts)
> w_plane = wrf_user_intrp3d(wa,z,"v",plane,0.,opts)
> printVarSummary(w_plane)
> printVarSummary(v_plane)
> printVarSummary(t_plane)
> dim = dimsizes(t_plane) ; Find the data span - for use in labels
> zspan = dim(0)
>
> ;************************************************
> ; Omega is significantly smaller than v, so we will
> ; scale it so that some vertical motion is visible
> ;************************************************
> wAve = avg(w_plane(:,:)) ; used for scaling
> vAve = avg(v_plane(:,:))
> scale = fabs(vAve/wAve)
> wscale = w_plane*scale ; now scale
>
> copy_VarCoords(w_plane, wscale) ; copy coordinate variables
> printVarSummary(wscale)
>
> print(t_plane!0)
> lev=wscale&Vertical
> lev@units=hPa
> t_plane!0="lev"
> t_plane!1="lon"
> v_plane!0="lev"
> v_plane!1="lon"
> wscale!0="lev"
> wscale!1="lon"
> printVarSummary(wscale)
> print(wscale&lev)
> print(t_plane!0)
> ;***********************************************
> ; create plot
> ;***********************************************
> wks = gsn_open_wks ("pdf", "vector" ) ; open workstation
> gsn_define_colormap(wks,"BlAqGrYeOrRevi200") ; choose color map
>
> res = True ; plot mods desired
> res@tiMainString = "Pressure/Height Vector" ; title
> res@TimeLabel = times(it) ; Set Valid time to use on plots
> res@cnLineLabelsOn = False ; turn off line labels
> res@cnFillOn = True ; turn on color fill
> res@lbLabelStride = 2 ; every other color
>
> res@gsnSpreadColors = True ; use full range of color map
>
> res@vcRefMagnitudeF = 3.0 ; define vector ref mag
> res@vcRefLengthF = 0.045 ; define length of vec ref
> res@vcGlyphStyle = "CurlyVector" ; turn on curley vectors
> res@vcMinDistanceF = 0.01 ; thin out vectors
> res@vcMapDirection = False
>
> ;*****************************************************
> ; draw plot from pole to pole at 170E
> ;*****************************************************
> plot = gsn_csm_pres_hgt_vector(wks,t_plane(:,:),v_plane(:,:),\
> wscale(:,:),res )
> end do
> end
>
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Received on Wed Apr 16 09:08:00 2014