[ncl-talk] limit map region for Lambert Conformal projection

[Dennis Shea]

It is the user's responsibility to look at the file being used.
---
WRF files are (generally) netCDF.
NARR files are GRIB files.

Different information is available for each:
---
%> *ncl_filedump* merged_AWIP32.1979010100.3D.NARR.*grb*

provides the following information for the GRIB file variables

[SNIP]
      float gridlat_221 ( gridx_221, gridy_221 )
         corners :      (  1, 0.8972797, 46.35283, 46.63458 )
         long_name :    latitude
         grid_description :     AWIPS - Regional - NOAMHI - High Resolution
North American Master Grid (Lambert Conformal)
         units :        degrees_north



*         mpLambertMeridianF :   253         mpLambertParallel2F :  50
   mpLambertParallel1F :  50         mpProjection : LAMBERTCONFORMAL*
         Dy :   32463.41
         Dx :   32463.41
         Lov :  253
         Lo1 :  214.5
         La1 :   1
=====================================
This information is *NOT* available on the WRF file.
Please examine the WRF file's global attributes:

%> ncdump -h wrfout...
or
%> ncl_filedump wrfout ...

Maybe something like:

[SNIP]
               :CEN_LAT = 43.99802f ;
                :CEN_LON = -98.f ;
                :TRUELAT1 = 30.f ;
                :TRUELAT2 = 60.f ;[SNIP]
[SNIP]

wrf = addfile("wrf...nc","r")
   ...
Something like:

res at mpLambertParallel1F   = fwrf->TRUELAT1
res at mpLambertParallel2F   = fwrf->TRUELAT2
res at mpLambertMeridianF    = fwrf->CEN_LON



On Tue, Jan 28, 2020 at 9:13 AM Zhifeng Yang <yangzf01 at gmail.com> wrote:

> Hi Dennis,
> Thank you. I tried to add
>   res at mpLimitMode            = "Corners"          ; choose range of map
>   res at mpLeftCornerLatF       = lat2d(0,0)
>   res at mpLeftCornerLonF       = lon2d(0,0)
>   res at mpRightCornerLatF      = lat2d(nlat-1,mlon-1)
>   res at mpRightCornerLonF      = lon2d(nlat-1,mlon-1)
> It can select map range. However, it seems that contour does not move
> along with map. So there is a shift between contour and map. Then I want to
> add
>   res at mpProjection           = "LambertConformal"
>   res at mpLambertParallel1F    = lat2d at mpLambertParallel1F
>   res at mpLambertParallel2F    = lat2d at mpLambertParallel2F
>   res at mpLambertMeridianF     = lat2d at mpLambertMeridianF
>
> The problem is there is no latitude attributes (mpLambertParallel1F,
> mpLambertParallel2F, mpLambertMeridianF) in wrfout files.
>
> Best,
> Zhifeng
>
> On Mon, Jan 27, 2020 at 6:06 PM Dennis Shea <shea at ucar.edu> wrote:
>
>> NARR are Lambert Conformat:
>>
>> *http://www.ncl.ucar.edu/Applications/narr.shtml*
>> <http://www.ncl.ucar.edu/Applications/narr.shtml>
>> ncl_3.ncl
>>
>> See plot section
>> ===
>> WRF projection information  is contained within the file attributes
>>
>>    fwrf = addfile("wrf...nc","r")
>>    ...
>> Something like:
>>
>> res at mpLambertParallel1F   = fwrf->Latin1
>> res at mpLambertParallel2F   = fwrf->Latin2
>> res at mpLambertMeridianF    = fwrf->LoV
>>
>> ========================================
>>
>>   res at gsnAddCyclic           = False              ; regional data
>>
>>   res at mpLimitMode            = "Corners"          ; choose range of map
>>   res at mpLeftCornerLatF       = lat2d(0,0)
>>   res at mpLeftCornerLonF       = lon2d(0,0)
>>   res at mpRightCornerLatF      = lat2d(nlat-1,mlon-1)
>>   res at mpRightCornerLonF      = lon2d(nlat-1,mlon-1)
>>   res at tfDoNDCOverlay         = True
>>   res at mpProjection           = "LambertConformal"
>>   res at mpLambertParallel1F    = lat2d at mpLambertParallel1F
>>   res at mpLambertParallel2F    = lat2d at mpLambertParallel2F
>>   res at mpLambertMeridianF     = lat2d at mpLambertMeridianF
>>
>>
>> On Mon, Jan 27, 2020 at 2:02 PM Zhifeng Yang via ncl-talk <
>> ncl-talk at ucar.edu> wrote:
>>
>>> Hi all,
>>> I have WRF output files with Lambert Conformal projection. When I plot
>>> images with contour on maps, I tried to limit the plot over a specific
>>> region, not the whole domain. I tried the following
>>>    res at mpLimitMode                  = "latlon"
>>>    res at mpMinLatF                    = minlat
>>>    res at mpMaxLatF                    = maxlat
>>>    res at mpMinLonF                    = minlon
>>>    res at mpMaxLonF                    = maxlon
>>>
>>> However, it seems it does not work. Do you have any ideas on it? Thank
>>> you!
>>>
>>> Best,
>>> Zhifeng
>>> _______________________________________________
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>>> ncl-talk at ucar.edu
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>>
>>
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