[ncl-talk] Question about SNODAS plot

[Rick Brownrigg]

Hi,

I can reproduce the issue. It really appears as though some stretching
transformation has been applied during the creation of the NetCDF file --
How/where was the file obtained?  I don't know for certain that WGS84 is
not the issue, but I would think it should not matter much at the scale of
a region as large as CONUS.

FWIW -- I found this document that describes to original SNODAS:

    https://nsidc.org/data/g02158

Rick

On Wed, Jun 5, 2019 at 9:05 AM 张雪岩 <xueyanzhang520 at gmail.com> wrote:

> Hi, I am plotting snow water equivalent using NCL. The following is my
> script:
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"
>
> begin
>
> f=addfile("/Users/xueyanzhang/NOHRSC_SNODAS-master/July_mean/201807.nc",
> "r")
> swe=f->SWE(0,:,:)
>
> ;;;;;;;;;;;;;;;;;;;;;;;;plot
> section;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>
> wks = gsn_open_wks("png", "201807_swe_mean")
> gsn_define_colormap(wks, "BlAqGrYeOrReVi200")
>
> setvalues NhlGetWorkspaceObjectId()
>   "wsMaximumSize" : 300000000
> end setvalues
>
> res = True
>
> res at gsnAddCyclic           = False
> res at gsnDraw                = False
> res at gsnFrame               = False
> res at gsnMaximize            = True
> res at gsnRightString         = "Snow water equivalent (mm)"
> res at gsnLeftString          = "201807 mean"
> res at gsnStringFontHeightF   = 0.01
>
>
> res at cnFillOn               = True
> res at cnLinesOn              = False
> res at cnLineLabelsOn         = False
> res at cnFillDrawOrder        = "PreDraw"
> res at cnFillMode             = "RasterFill"
> res at cnLineLabelsOn         = False
> res at cnLevelSelectionMode   = "ManualLevels"
> res at cnMinLevelValF         = 0
> res at cnMaxLevelValF         = 1000
> res at cnLevelSpacingF        = 50
>
> res at mpFillOn                = False           ; turn off map fill
> res at mpDataBaseVersion       = "MediumRes"
> res at mpOutlineBoundarySets   = "USStates"
> res at mpProjection     = "CylindricalEquidistant"
> res at mpOutlineDrawOrder      = "PostDraw"  ; draw continental outline last
> res at mpGeophysicalLineColor  = "Black"
> res at mpNationalLineColor     = "Black"
> res at mpLimbLineColor         = "Black"
> res at mpPerimLineColor        = "Black"
> res at mpUSStateLineColor      = "black"
> res at mpGeophysicalLineThicknessF = 2.
> res at mpLandFillColor         = "white"
> res at mpInlandWaterFillColor  = "white"
> res at mpOceanFillColor        = "white"
>
> res at mpLimitMode              = "LatLon"
> res at mpMaxLatF                = 53
> res at mpMinLatF                = 23
> res at mpMaxLonF                = -65
> res at mpMinLonF                = -125
> ;res at mpCenterLatF             = (53+23)/2
> ;res at mpCenterLonF             = (-65-125)/2
>
> plot = gsn_csm_contour_map(wks, swe, res)
>
> draw(plot)
> frame(wks)
>
>
> end
>
>
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> But the plot is not consistent with the map NCL provides.
>
> I searched and found it may be because of WGS84, this datum. But I don’t
> know how to solve it. Can you help me?
>
> Xueyan_______________________________________________
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