[ncl-talk] contour map not showing colors

[Rick Brownrigg]

Hi Tabish,

I'm not seeing the problem -- it is indeed a straightforward script.  If
you can send me that dataset, I'll take a closer look into it.

Rick

On Tue, Aug 13, 2024 at 9:49 AM Tabish Ansari via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Hi
>
> I have a cropped dataset over northern China from the CAMS Reanalyses
> product which contains 3-hourly PM2.5 concentrations for the year 2019.
>
> Here's the variable metadata:
>         short pm2p5(time, latitude, longitude) ;
>                 pm2p5:scale_factor = 7.76424835780384e-11 ;
>                 pm2p5:add_offset = 2.54403361691801e-06 ;
>                 pm2p5:_FillValue = -32767s ;
>                 pm2p5:missing_value = -32767s ;
>                 pm2p5:units = "kg m**-3" ;
>                 pm2p5:long_name = "Particulate matter d < 2.5 um" ;
>                 pm2p5:standard_name =
> "mass_concentration_of_pm2p5_ambient_aerosol_particles_in_air" ;
>
>
> I've written a fairly straightforward NCL script just to plot the annual
> average PM2.5 concentration. It shows the map with contour lines and an
> appropriately ranged labelbar but with no colors within the map.
> Here's my script:
>
> ==============================================================================
> begin
>
> ;SOURCING FILES
> DIR = "/worknb/users/tans/Capstone-Maya/"
> a   = addfile(DIR+"CAMSconc_3hourly_NCP2019.nc","r")
>
>
> ;READING DATA
> pm25NCP = short2flt(a->pm2p5)
> pm25NCP = pm25NCP * 10^9
> pm25NCP = pm25NCP(:,::-1,:) ; flipping latitudes to correct the inverted
> data
>
>
> ;PREPARING TIME-AVERAGED DATA
> pm25NCPavg = dim_avg_n_Wrap(pm25NCP,0)
> printVarSummary(pm25NCPavg)
> printMinMax(pm25NCPavg,True)
>
>
> ;START THE GRAPHICS
> wks = gsn_open_wks("x11","NCPavgconc")
> res                     = True
> res at gsnMaximize         = True           ; Maximize plot in frame
> res at cnFillOn            = True           ; turn on color
> ;res at cnFillPalette       = "MPL_Reds"     ; set color map
> res at cnLinesOn           = True           ; turn contour lines on/off
> res at gsnAddCyclic        = False
> res at mpFillOn            = True
>
> ;SELECT NCP REGION FROM THE GLOBE
> res at mpProjection           = "Mercator"
> res at mpLambertParallel1F    = 30.
> res at mpLambertParallel2F    = 40.
> res at mpLambertMeridianF     = 115.
>
> res at mpLimitMode            = "Corners"          ; choose region of map
> res at mpLeftCornerLatF       = 20.
> res at mpLeftCornerLonF       = 100.
> res at mpRightCornerLatF      = 50.
> res at mpRightCornerLonF      = 130.
>
> plot = gsn_csm_contour_map(wks, pm25NCPavg, res)
>
> end
> ===================================================================
>
>
> The output of the script is as follows:
>  Copyright (C) 1995-2019 - All Rights Reserved
>  University Corporation for Atmospheric Research
>  NCAR Command Language Version 6.6.2
>  The use of this software is governed by a License Agreement.
>  See http://www.ncl.ucar.edu/ for more details.
>
> Variable: pm25NCPavg
> Type: float
> Total Size: 6724 bytes
>             1681 values
> Number of Dimensions: 2
> Dimensions and sizes:   [latitude | 41] x [longitude | 41]
> Coordinates:
>             latitude: [20..50]
>             longitude: [100..130]
> Number Of Attributes: 8
>   _FillValue :  -32767
>   units :       kg m**-3
>   long_name :   Particulate matter d < 2.5 um
>   standard_name :
> mass_concentration_of_pm2p5_ambient_aerosol_particles_in_air
>   _FillValue_original : -32767
>   missing_value_original :      -32767
>   missing_value :       -32767
>   average_op_ncl :      dim_avg_n over dimension(s): time
> (0)
> (0)     Particulate matter d < 2.5 um (kg m**-3) : min=3.35468
> max=205.552
>
>
>
> And I have attached the resulting map as a png file.
>
> I'd really appreciate it if someone can point out what is needed for the
> plot to show the contour colors.
>
> Thanks a lot.
>
> best regards,
>
> Tabish
>
>
> --------------------------------------------------------------------------------------
> Dr Tabish Ansari
> Research Associate
> Air Quality Modelling Group
> Research Institute for Sustainability (RIFS) - Helmholtz Centre Potsdam
> Potsdam, Germany
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