[ncl-talk] gsn_contour_map, zoom in plot problem

[Ying Song]

Hello, Mary,

I modified my script following your first suggestion. The problem is still
there. The warning msg shows:
-------------------------------------------------
Variable: o3_p
Type: float
Total Size: 831744 bytes
            207936 values
Number of Dimensions: 2
Dimensions and sizes:   [lat | 361] x [lon | 576]
Coordinates:
            lat: [ -90..  90]
            lon: [-180..179.375]
Number Of Attributes: 13
  lev :  900
  time :        540
  long_name :   ozone mixing ratio
  units :       ppbv
  _FillValue :  1e+15
  missing_value :       1e+15
  fmissing_value :      1e+15
  scale_factor :         1
  add_offset :   0
  standard_name :       ozone_mass_mixing_ratio
  vmax :        1e+15
  vmin :        -1e+15
  valid_range : ( -1e+15, 1e+15 )
warning:ContourPlotDraw: out of range coordinates encountered; standard
AreaFill rendering method may be unreliable;
 consider setting the resource trGridType to "TriangularMesh" if
coordinates contain missing values
-------------------------------------
And I attached the updated script. I wounder if I need to add triangular
meshes resource in my script?

Thanks!

On Thu, Sep 7, 2017 at 8:46 AM, Mary Haley <haley at ucar.edu> wrote:

> I think the issue is that "o3_p", which is the variable you are trying to
> plot, doesn't have any metadata attached to it.
>
> When you do calculations like this in NCL:
>
>    o3= a->O3(3,4,:,:) ; 18GTM = 11AM PST
>
>   printVarSummary(o3)
>    o3_p =(o3*1e9)*(28.97/48)
>
> The "o3" will have metadata because no computations were done when you
> read the variable off the file.
>
> However, since o3_p involves calculations, NCL will strip all the metadata
> and the only thing that o3_p will retain from o3 is the _FillValue
> attribute, if any.
>
> As a "trick", you can force o3_p to have the same metadata by doing the
> following:
>
>    o3_p = a->O3(3,4,:,:) ; 18GTM = 11AM PST
>
>    o3_p =(o3_p*1e9)*(28.97/48)
>
> The first line will read the data into o3_p, and the metadata will all be
> there. Then, when you do the calculation, since o3_p already exists, no
> metadata will be removed.
>
> Note that I removed the use of o3, just to save memory. If you need to
> keep o3 and o3_p around, then you can do:
>
>    o3 = a->O3(3,4,:,:) ; 18GTM = 11AM PST
>    o3_p = o3           ; trick to copy metadata
>    o3_p =(o3*1e9)*(28.97/48)
>
> You should however, update the long_name and units attributes of o3_p, to
> reflect what the new values represent.
>
> --Mary
>
>
> On Wed, Sep 6, 2017 at 5:05 PM, Ying Song <ying.song at sjsu.edu> wrote:
>
>> Hello, ncl helper,
>>
>> I trying to plot MERRA-2 reanalysis data in NCL using gsn_contour_map. I
>> am only interested in west coast of US.  But I can not get the zoom in plot
>> correctly by using resources:
>>
>>   res at mpMinLatF               = 30
>>   res at mpMaxLatF               = 45
>>   res at mpMinLonF               = -130
>>   res at mpMaxLonF               = -110
>>
>> The warning shows:
>> warning:ContourPlotDraw: out of range coordinates encountered; standard
>> AreaFill rendering method may be unreliable;
>>  consider setting the resource trGridType to "TriangularMesh" if
>> coordinates contain missing values
>>
>> Attachment is my script. The info of MERRA-2 O3 data from printVarSummary
>> is:
>>  ------------------------------
>> Variable: o3
>> Type: float
>> Total Size: 279465984 bytes
>>             69866496 values
>> Number of Dimensions: 4
>> Dimensions and sizes:   [time | 8] x [lev | 42] x [lat | 361] x [lon |
>> 576]
>> Coordinates:
>>             time: [0..1260]
>>             lev: [1000..0.1000000014901161]
>>             lat: [ -90..  90]
>>             lon: [-180..179.375]
>> Number Of Attributes: 11
>>   long_name :   ozone_mass_mixing_ratio
>>   units :       kg kg-1
>>   _FillValue :  1e+15
>>   missing_value :       1e+15
>>   fmissing_value :      1e+15
>>   scale_factor :         1
>>   add_offset :   0
>>   standard_name :       ozone_mass_mixing_ratio
>>   vmax :        1e+15
>>   vmin :        -1e+15
>>   valid_range : ( -1e+15, 1e+15 )
>> ---------------------------------------------------------
>>
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