Re: Error message concerning latitude and longitude

Hi folks,

Sorry, I violated the rule of "look at your data". Dennis is right, the array already contains coordinate arrays, so you don't need the sfXArray/sfYArray.

What threw me is that the error message you included below didn't have anything about incorrect "units" for lat/lon. You should have also seen a helpful statement that says something like:

     A valid latitude coordinate array should have a 'units' attribute equal to one of the following values:

This would have been followed by a list of allowable units, like "degrees_north", etc. This is usually a clue right away that you probably have a coordinate array, but that you need to fix the units, as Dennis suggested.

--Mary

On Dec 12, 2013, at 7:50 AM, Dennis Shea <shea@ucar.edu> wrote:

> Actually, the CDO produced coordinates are 'coordinate arrays'
> [one dimensional with the named dimension the same as the
> variable name: rlat(rlat) and rlon(rlon)].
>
> An issue is that the coordinate array units are "degrees"
> for both rlon and rlat.
>
> double rlon(rlon) ;
> rlon:standard_name = "grid_longitude" ;
> rlon:long_name = "longitude in rotated pole grid" ;
> rlon:units = "degrees" ;
> rlon:axis = "X" ;
> double rlat(rlat) ;
> rlat:standard_name = "grid_latitude" ;
> rlat:long_name = "latitude in rotated pole grid" ;
> rlat:units = "degrees" ;
> rlat:axis = "Y" ;
>
> NCL is looking for 'degrees_east' and 'degrees_north' when plotting.
> This is easy to change
>
> T=f->var167(0,0,:,:)
> T&rlat@units = "degrees_north" ; <== units needed for plotting
> T&rlon@units = "degrees_east"
>
> As noted, there is currently one example of plotting rotated grids
>
> http://www.ncl.ucar.edu/Applications/
>
> Under "Map Projections", click "Rotated lat-lon"
> The is a bit more complicated than is needed but you should
> look at the code anyway.
>
> The attached shows assorted options.
>
> Good luck
>
> On 12/12/13, 7:35 AM, Mary Haley wrote:
>> Dear Stephan,
>>
>> It looks like you have a curvilinear grid (2D lat/lon arrays). You need to associate rlat/rlon with your data when you call gsn_csm_xxx_map, otherwise NCL won't know where on a map to plot your data.
>>
>> Try adding these three lines:
>>
>> res@sfXArray = f->rlon
>> res@sfYArray = f->rlat
>> res@gsnAddCyclic = False
>>
>> Also, since you have a rotated grid, you may want to plot the data in the correct rotated projection. Please see the first (only) example at:
>>
>> http://www.ncl.ucar.edu/Applications/rotatedltln.shtml
>>
>> Read the description on the above page about how to get the correct map projection.
>>
>> I would recommend writing an NCL script in a UNIX editor, rather than trying to do all of this interactively. Once you save the script, calling it something like "plot_temp.ncl", you run it on the UNIX command line with:
>>
>> ncl plot_temp.ncl
>>
>> Good luck,
>>
>> --Mary
>>
>> On Dec 12, 2013, at 6:47 AM, Stephan Herrmann <stephan.w.herrmann@t-online.de> wrote:
>>
>>>
>>>
>>> Hello everybody,
>>>
>>> I have calculated the mean temperature of Bolivia (1961-1970) with Climate Data Operators. The result is saved in the file: MPIM-REMO_EH5OMA1Br3_HR_044_BOL_1961-1970_167_timemean.nc. I want to plot the result with NCL and get the following error message:
>>>
>>> (0) check_for_y_lat_coord: Warning: Data either does not contain a valid latitude coordinate array or doesn't contain one at all.
>>> lines 1-1/1 (END)
>>>
>>> I need the plot for my diploma thesis in Meteorology.
>>>
>>> The NCL code is as follows:
>>>
>>> Copyright (C) 1995-2013 - All Rights Reserved
>>> University Corporation for Atmospheric Research
>>> NCAR Command Language Version 6.1.2
>>> The use of this software is governed by a License Agreement.
>>> See http://www.ncl.ucar.edu/ for more details.
>>>
>>> ncl 0> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>>> ncl 1> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>>> ncl 2> begin
>>> ncl 3> f = addfile("MPIM-REMO_EH5OMA1Br3_HR_044_BOL_1961-1970_167_timemean.nc","r")
>>> ncl 4> T=f->var167(0,0,:,:)
>>> ncl 5> wks=gsn_open_wks("ps","Bolivia_Timemean_1961-1970")
>>> ncl 6> res = True
>>> ncl 7> res@gsnMaximize = True
>>> ncl 8> res@tiMainString = "Bolivia_Timemean_1961-1970"
>>> ncl 9> plot = gsn_csm_contour_map(wks,T,res)
>>> ncl 10> end
>>>
>>> I have seen this problem before in this list, but I could not make it work using those tips.
>>>
>>> Here are the information about the variable "var167" and the variable "T":
>>>
>>> Variable: var167
>>> Type: float
>>> Total Size: 18544 bytes
>>> 4636 values
>>> Number of Dimensions: 4
>>> Dimensions and sizes: [time | 1] x [height | 1] x [rlat | 76] x [rlon | 61]
>>> Coordinates:
>>> time: [19710101..19710101]
>>> height: [ 2.. 2]
>>> rlat: [-20.68..12.32]
>>> rlon: [157.56..183.96]
>>> Number Of Attributes: 1
>>> grid_mapping : rotated_pole
>>>
>>> Variable: T
>>> Type: float
>>> Total Size: 18544 bytes
>>> 4636 values
>>> Number of Dimensions: 2
>>> Dimensions and sizes: [rlat | 76] x [rlon | 61]
>>> Coordinates:
>>> rlat: [-20.68..12.32]
>>> rlon: [157.56..183.96]
>>> Number Of Attributes: 3
>>> height : 2
>>> time : 19710101
>>> grid_mapping : rotated_pole
>>>
>>> I have renamed rlat to lat and rlon to lon but this does not solve the problem. The error message still occur. I hope you can help me.
>>>
>>> Attachment: file MPIM-REMO_EH5OMA1Br3_HR_044_BOL_1961-1970_167_timemean.nc
>>>
>>>
>>> Best regards
>>>
>>> Stephan<MPIM-REMO_EH5OMA1Br3_HR_044_BOL_1961-1970_167_timemean.nc>_______________________________________________
>>> ncl-talk mailing list
>>> List instructions, subscriber options, unsubscribe:
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>>
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Received on Thu Dec 12 08:02:03 2013