[gradsusr] Eurocentric global map
James T. Potemra
jimp at hawaii.edu
Tue Nov 19 13:19:53 EST 2013
Chuck/Cara:
If you define a variable from lon=0 to 360, then try and plot it
from 180 to 540, you will only get the part 180 to 360 (where
it is defined). If instead you define the variable from 180 to 540
you should be able to plot it over that range.
All this assumes that the variable's longitude is continuously
defined across 360. Cara, if you attach your descriptor file we
can figure this out. Or, check the XDEF line; if your variables
are defined from 0 to 360, check the number of points and
X-increment to see if continuous. For example, if you have
something like:
XDEF 360 LINEAR 0.5 1.0
x=1 corresponds to lon=0.5, x=2 corresponds to lon=1.5, etc
to x=360 corresponds to lon=359.5. So, x=361 will match with
360.5 which is the same as 0.5 and x=1. So, in this case the
longitudes are continuous.
Jim
On 11/19/13 7:27 AM, Charles Seman - NOAA Federal wrote:
> Jim, Cara,
>
> I just tried plotting the variable *defined* for lon = (0,360) for lon =
> (180,540), and now the *right* half of the map is missing. It appears
> that *defined* variables are only valid on the domain for which they are
> defined, while *dataset* variables can be plotted for domains outside of
> the domain specified in the metadata (or data descriptor file).
> Apparently, GrADS knows how to "wrap" in the longitude direction for a
> dataset variable, but does not do this for a defined variable...
>
> Can you try defining the variable of interest for lon = (-180,180) or as
> Alan suggested lon = (-170,190), or whatever domain on which you wish to
> plot it? Another alternative would be to write out the variable defined
> on lon = (0,360) to a dataset, open that dataset, and work with that
> dataset variable...
>
> Hope this helps,
> Chuck
>
> On 11/19/2013 11:22 AM, James T. Potemra wrote:
>> Cara:
>>
>> Can you try 'set lon 180 540'? This should work if your longitude
>> values are continuous.
>>
>> Jim
>> On 11/19/13 5:44 AM, Cara Duckworth wrote:
>>> Hi Chuck,
>>>
>>> Thanks for your response. Yes, I just checked: lon = 0,360.
>>>
>>> Is there a way that I can change this so that I can plot the global map from lon -180 to 180 (with Europe in the middle)?
>>> When I plot it at lon=0,360, the map is fine but America is in the centre and I need Europe in the centre.
>>>
>>> Best,
>>> Cara
>>>
>>> On 19 Nov 2013, at 15:15, Charles Seman - NOAA Federal <charles.seman at noaa.gov> wrote:
>>>
>>>> Cara,
>>>>
>>>> Check to see if the variable you're trying to plot has been defined
>>>> locally in GrADS and what the longitude range is for it. I was able to
>>>> replicate the issue by defining a local GrADS variable for lon = (0,360)
>>>> and then when displaying it for lon = (-180,180) the left half was missing.
>>>>
>>>> Hope this helps,
>>>> Chuck
>>>>
>>>> On 11/19/2013 09:33 AM, Cara Duckworth wrote:
>>>>> Thanks Alan and Chris,
>>>>>
>>>>> I'm still having troubles plotting the map.
>>>>> When I use "set lon -180 180", one half of the plot is missing (see
>>>>> image attached)
>>>>>
>>>>> Without this instruction the map is fine (with all data displayed),
>>>>> though Europe is not in the centre.
>>>>> Any ideas as to what I have done wrong?
>>>>>
>>>>> Best,
>>>>> Cara
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 19 Nov 2013, at 13:25, Bill Reilly <bill_reilly at compuserve.com
>>>>> <mailto:bill_reilly at compuserve.com>> wrote:
>>>>>
>>>>>> Alan:
>>>>>>
>>>>>> I think you mean:
>>>>>>
>>>>>> set lon -180 180
>>>>>>
>>>>>> --
>>>>>>
>>>>>> Bill Reilly
>>>>>> www.passageweather.com <http://www.passageweather.com>
>>>>>>
>>>>>> On 11/19/2013 1:30 PM, Alan Robock wrote:
>>>>>>> Dear Cara
>>>>>>>
>>>>>>> set lat -180 180
>>>>>>>
>>>>>>> or if you don't want to split Alaska:
>>>>>>>
>>>>>>> set lat -170 190
>>>>>>> Alan Robock
>>>>>>>
>>>>>>> Alan Robock, Distinguished Professor
>>>>>>> Editor, Reviews of Geophysics
>>>>>>> Director, Meteorology Undergraduate Program
>>>>>>> Department of Environmental Sciences Phone: +1-848-932-5751
>>>>>>> Rutgers University Fax: +1-732-932-8644
>>>>>>> 14 College Farm Road E-mail:robock at envsci.rutgers.edu
>>>>>>> New Brunswick, NJ 08901-8551 USAhttp://envsci.rutgers.edu/~robock
>>>>>>> http://twitter.com/AlanRobock
>>>>>>> Watch my 18 min TEDx talk athttp://www.youtube.com/watch?v=qsrEk1oZ-54
>>>>>>>
>>>>>>> On 11/19/2013 6:54 AM, Cara Duckworth wrote:
>>>>>>>> Dear users,
>>>>>>>>
>>>>>>>> I need to plot a global map, which is centred on the Prime Meridian
>>>>>>>> (i.e. a Eurocentric map).
>>>>>>>> Currently, the Prime Meridian is at either edge of my plot. How do I
>>>>>>>> change this?
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Cara
>>>>>>>>
>>>>>>>>
>>>>>>>>
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>>>> --
>>>>
>>>> Please note that Charles.Seman at noaa.gov should be considered my NOAA
>>>> email address, not cjs at gfdl.noaa.gov.
>>>>
>>>> ********************************************************************
>>>> Charles Seman Charles.Seman at noaa.gov
>>>> U.S. Department of Commerce / NOAA / OAR
>>>> Geophysical Fluid Dynamics Laboratory voice: (609) 452-6547
>>>> 201 Forrestal Road fax: (609) 987-5063
>>>> Princeton, NJ 08540-6649 http://www.gfdl.noaa.gov/~cjs/
>>>> ********************************************************************
>>>>
>>>> "The contents of this message are mine personally and do not reflect any
>>>> official or unofficial position of the United States Federal Government,
>>>> the United States Department of Commerce, or NOAA."
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