Hi Dennis,
It works, thanks so much for spending some time to help me.
Regards
Sudipta Sarkar
----- Original Message -----
From: "Dennis Shea" <shea@cgd.ucar.edu>
To: <ncl-talk@ucar.edu>; <ssarkar@forestone.com>
Sent: Friday, October 07, 2005 4:59 PM
Subject: Re: Regridding question
> Hello,
>
> Pls see attached text. It will do the interpolation.
>
> A few comments for a person "new to NCL"
>
> [1] pc(lat_2,lon_2) ; [ 90N -> 90S]
>
> In NCL, use array syntax to reverse the order of
> a dimension.
>
> pc = pc(::-1,:) ; [ 90S -> 90N] done "in place"
>
> [2] There are *negative* prc values.
> This may indicate that values originated with
> a spectral model.
>
> [3] Become familiar with
> [a] contributed.ncl
> [b] the "Application Examples"
>
> They are your friends :-)
>
>
> [4] GRIB files generqally do not come with the ".grb"
> extension. This is not required for the file name.
> If the file name is
>
> gfs.t00z.pgrbf192
>
> Then you can use:
>
> f = addfile("gfs.t00z.pgrbf192.grb","r")
>
> NCL will look for the file " gfs.t00z.pgrbf192.grb",
> If this is not found, NCL will look for the file
> "gfs.t00z.pgrbf192" but 'remember' to treat it
> as a GrIB file.
>
> This goes for netCDF, hdf, hdfeos, etc
> Onny in addfile must the extension occure. This
> tells NCL how to read the file
>
>
> good luck
> D
>
> ===========================================================
> Hi Guys,
> I am new to NCL and am trying to convert a 73x144 lat lon grid to a
> 181x360 lat
> lon grid using the linint2 function. Heres what I have done so far:
>
> gfile=addfile("gfs.t00z.pgrbf192.grb","r") ;read a GFS model grib file
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclex/gsun/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> pc=gfile->A_PCP_2_SFC_acc12h ; read the 12 hour Total surface ppt (lat|
> 73, lon|
> 144)
>
> ; Since linint2 expects lat array in ascending order hence:
> pcflip = new((/73,144/),float)
> k=72
> do i = 0,72
> pcflip(i,:) = pc(k,:)
> k = k-1
> end do
> newlon=fspan(0.,359,360) ; define new longitude
> newlat=fspan(-90.,90,181) ; define new output latitude
> pc_regrid =
> linint2_Wrap(pcflip&lon_2,pcflip&lat_2,pcflip,False,newlon,newlat,0)
>
> ; Then flip the data back again along the latitude
> k = 180
> do i = 0,180
> pcregrid_flip(i,:) = pc_regrid(k,:)
> k = k-1
> end do
>
> So my final regridded varibale is pcregrid_flip
> I am not sure i am doing the right thing here? the plots of the original
> and
> regridded variables looks somewhat different which maybe due to
> interpolation
> but i just want to make sure from you guys. Also shuold i use f2sfh
> insetad of
> linint2??
> Any suggestion will be most welcome
> Thanks
>
> Sudipta Sarkar
>
--------------------------------------------------------------------------------
>
>
> load "$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"
>
> begin
> diri = "/project/cas/shea/GRIB/"
> fili = "gfs.t00z.pgrbf192"
> var = "A_PCP_2_SFC_acc12h"
>
> f = addfile(diri+fili+".grb","r")
> pc = f->$var$ ; North to South
> ;print(f) ; like ncdump [overview of file]
>
> printVarSummary(pc)
> printMinMax(pc, True) ; This has *negative* values
> ;************************************************
> ; bilinear interpolation
> ;************************************************
> nlat = 181
> mlon = 360
> latNew= latGlobeF (nlat, "lat", "latitude", "degrees_north")
> lonNew= lonGlobeF (mlon, "lon", "longitude", "degrees_east")
>
> pc = pc(::-1,:) ; South to North for linint2
> printVarSummary(pc) ; Note coordinate arrays
> printMinMax(pc, True)
>
> pcNew = linint2_Wrap(pc&lon_2,pc&lat_2,pc,True ,lonNew,latNew,0)
>
> printVarSummary(pcNew)
> printMinMax(pcNew, True)
>
> pcNew = pcNew(::-1,:) ; North to South
> printVarSummary(pcNew)
>
> itime = pc@initial_time
> ftime = pc@forecast_time
>
> ;************************************************
> ; create plots
> ;************************************************
> wks = gsn_open_wks("x11","ssarkar_prc")
> ;gsn_define_colormap(wks,"gui_default")
>
> colors = (/"white","black" \ ; back/fore ground
> ,"blue","azure1","beige","lavender" \
> ,"PaleGreen","SeaGreen3","yellow" \
> ,"magenta","HotPink","Red"/) ; choose colors for color
> map
> gsn_define_colormap(wks, colors) ; generate new color map
>
> plot = new(2,graphic) ; create a plot array
>
> res = True
> res@gsnDraw = False ; don't draw
> res@gsnFrame = False ; don't advance frame
> res@cnInfoLabelOn = False ; turn off cn info label
> res@cnFillOn = True ; turn on color
> res@lbLabelBarOn = False ; turn off individual cb's
>
>
> res@cnLevelSelectionMode= "ExplicitLevels" ; set explicit contour
> levels
> ; specify unequal contour
> levels
> res@cnLevels = (/ 0.0, 1.0, 3.0, 5.0 ,10 ,15 ,25 ,50, 75 /)
>
> res@gsnCenterString = "2.5"
> plot(0) = gsn_csm_contour_map_ce(wks,pc,res)
> res@gsnCenterString = "1x1"
> plot(1) = gsn_csm_contour_map_ce(wks,pcNew,res)
> ;************************************************
> ; create panel
> ;************************************************
> resP = True ; modify the panel plot
> resP@txString = "itime="+itime+" ftime="+ftime
> resP@gsnPanelLabelBar = True ; add common colorbar
> resP@gsnMaximize = True ; if "ps" will make large
> gsn_panel(wks,plot,(/2,1/),resP) ; now draw as one plot
> end
>
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