[ncl-talk] Contour plot with rotated grid shifted to the west
Mary Haley
haley at ucar.edu
Mon Nov 30 13:18:47 MST 2015
Guido,
I looked at your script further, and I think the issue is with the map
corners you've selected. You are using the 1D rotated coordinate arrays to
choose the corners, but this is likely not correct. What you really need
are the original 2D lat/lon values, as the two examples illustrated, but I
don't see that you have this information on the file.
Did you try plotting the data using the coordinate arrays? I've created a
script for you to try, although it's untested because I don't have your
data file.
Thanks,
--Mary
On Mon, Nov 30, 2015 at 11:45 AM, Guido Cioni <guidocioni at gmail.com> wrote:
> Sure, here it is. I think that the problem is that ncl is expecting 2-D
> latitudes and longitudes while I have 1-D rlon and rlat..
>
> Yes I tried commenting the centers.
>
> m300382 at mlogin103% ncl_filedump complete.nc
> Copyright (C) 1995-2015 - All Rights Reserved
> University Corporation for Atmospheric Research
> NCAR Command Language Version 6.3.0
> The use of this software is governed by a License Agreement.
> See http://www.ncl.ucar.edu/ for more details.
>
> Variable: f
> Type: file
> filename: complete
> path: complete.nc
> file global attributes:
> CDI : Climate Data Interface version 1.4.7 (
> http://code.zmaw.de/projects/cdi)
> Conventions : CF-1.0
> history : Fri Nov 27 13:33:35 2015: cdo -f nc copy 2014011700_000.grib2
> 2014011700_001.grib2 2014011700_002.grib2 2014011700_003.grib2
> 2014011700_004.grib2 2014011700_005.grib2 2014011700_006.grib2
> 2014011700_007.grib2 2014011700_008.grib2 2014011700_009.grib2
> 2014011700_010.grib2 2014011700_011.grib2 2014011700_012.grib2
> 2014011700_013.grib2 2014011700_014.grib2 2014011700_015.grib2
> 2014011700_016.grib2 2014011700_017.grib2 2014011700_018.grib2
> 2014011700_019.grib2 2014011700_020.grib2 2014011700_021.grib2
> 2014011700_022.grib2 2014011700_023.grib2 2014011700_024.grib2
> 2014011700_025.grib2 2014011700_026.grib2 2014011700_027.grib2
> 2014011700_028.grib2 2014011700_029.grib2 2014011700_030.grib2
> 2014011700_031.grib2 2014011700_032.grib2 2014011700_033.grib2
> 2014011700_034.grib2 2014011700_035.grib2 2014011700_036.grib2
> 2014011700_037.grib2 2014011700_038.grib2 2014011700_039.grib2
> 2014011700_040.grib2 2014011700_041.grib2 2014011700_042.grib2
> 2014011700_043.grib2 2014011700_044.grib2 2014011700_045.grib2
> 2014011700_046.grib2 2014011700_047.grib2
> CDO : Climate Data Operators version 1.4.7 (
> http://code.zmaw.de/projects/cdo)
> dimensions:
> ncl_scalar = 1
> rlon = 706
> rlat = 434
> lev = 20
> time = 73 // unlimited
> variables:
> double rlon ( rlon )
> long_name : longitude in rotated pole grid
> units : degrees
> standard_name : grid_longitude
> axis : X
>
> double rlat ( rlat )
> long_name : latitude in rotated pole grid
> units : degrees
> standard_name : grid_latitude
> axis : Y
>
> character rotated_pole ( ncl_scalar )
> grid_mapping_name : rotated_latitude_longitude
> grid_north_pole_latitude : 44.999996
> grid_north_pole_longitude : 144
>
> double lev ( lev )
> long_name : pressure
> units : Pa
> axis : Z
>
> double time ( time )
> units : hours since 2014-01-17 00:00:00
> calendar : proleptic_gregorian
>
> float gh ( time, lev, rlat, rlon )
> long_name : Geopotential Height
> units : gpm
> code : 5
> grid_mapping : rotated_pole
>
> float t ( time, lev, rlat, rlon )
> long_name : Temperature
> units : K
> grid_mapping : rotated_pole
>
> float u ( time, lev, rlat, rlon )
> long_name : U velocity
> units : m s**-1
> code : 2
> grid_mapping : rotated_pole
>
> float v ( time, lev, rlat, rlon )
> long_name : V velocity
> units : m s**-1
> code : 3
> grid_mapping : rotated_pole
>
> float w ( time, lev, rlat, rlon )
> long_name : Vertical velocity
> units : Pa s**-1
> code : 8
> grid_mapping : rotated_pole
>
> float pv ( time, lev, rlat, rlon )
> long_name : Potential vorticity
> units : K m**2 kg**-1 s**-1
> code : 14
> grid_mapping : rotated_pole
>
> float mterh ( time, rlat, rlon )
> long_name : Model terrain height
> units : m
> code : 7
> grid_mapping : rotated_pole
> Il 30 nov 2015 6:28 PM, "Mary Haley" <haley at ucar.edu> ha scritto:
>
>> Guido,
>>
>> I'm hoping Dave will weigh in here, but it would help if we could at
>> least see the output from:
>>
>> ncl_filedump pv.nc
>>
>> Sometimes the global attributes of the file will give some valuable
>> information about the correct map projection parameters.
>>
>> Did you actually try commenting out the mpCenterLatF and mpCenterLonF
>> settings? In the script you included, these two resources are still being
>> set.
>>
>> It's possible that the data has already been rotated for you.
>>
>> --Mary
>>
>>
>>
>>
>> On Mon, Nov 30, 2015 at 1:33 AM, Guido Cioni <guidocioni at gmail.com>
>> wrote:
>>
>>> Hi all,
>>> I’m trying to produce a contour plot with data on a rotated grid. The
>>> original data look like that
>>>
>>>
>>> Since I have the rotated north pole latitude (*44.999996*) and
>>> longitude (*144.0*) in my data file I used the second example of the
>>> support page on rotated grid.
>>>
>>> Res1 at tfDoNDCOverlay=True
>>> Res1 at mpLimitMode = "Corners"
>>> Res1 at mpLeftCornerLatF = lat(0)
>>> Res1 at mpLeftCornerLonF = lon(0)
>>> Res1 at mpRightCornerLatF = lat(nlat-1)
>>> Res1 at mpRightCornerLonF = lon(nlon-1)
>>> Res1 at mpCenterLatF = 90 - north_pole_lat
>>> Res1 at mpCenterLonF = 180 + north_pole_lon
>>>
>>> However I get this result ( I believe this is Australia):
>>>
>>>
>>> After several attempts I was able to plot the data using as bounds the
>>> “real” coordinates of the rotated projection, without specifying the
>>> center, e.g. :
>>>
>>> Res1 at tfDoNDCOverlay=True
>>> Res1 at mpLimitMode = "Corners"
>>> Res1 at mpLeftCornerLatF = 30.35458
>>> Res1 at mpLeftCornerLonF = -75.14440
>>> Res1 at mpRightCornerLatF = 65.1125
>>> Res1 at mpRightCornerLonF = 13.87071
>>>
>>> But the contour plot is still slightly shifted to the west as you can
>>> see in this image:
>>>
>>>
>>> I know that in the data file my coordinates span from rlon={340,392.875}
>>> and rlat={-9.962499,22.512501}.
>>>
>>> What am I missing?
>>> Is there any additional documentation on rotated grid?
>>>
>>> Attached is my NCL script (data are too big).
>>>
>>>
>>>
>>> Guido Cioni
>>> http://guidocioni.altervista.org
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> ncl-talk at ucar.edu
>>> List instructions, subscriber options, unsubscribe:
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>>>
>>>
>>
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