Re: Converting axis coordinates

Hi Gerry,
(see below)

On 09/15/2011 01:08 PM, Gerald Creager wrote:
> Hello, Adam,
>
> I've tried that but I get an error:
> (0) gsn_add_cyclic: Warning: The range of your longitude data is not 360.
> (0) You may want to set gsnAddCyclic to False to avoid a warning
> (0) message from the spline function.
> warning:_NhlCreateSplineCoordApprox: Attempt to create spline
> approximation for X axis failed: consider adjusting trXTensionF value
> warning:IrTransInitialize: error creating spline approximation for
> trXCoordPoints; defaulting to linear

When you are plotting regional data on a map, you need to tell NCL that
the data is regional so it doesn't try to wrap your data around the
cyclic point. This is one of the more common error messages, and in this
case it tells you what to do: set gsnAddCyclic = False.

>
> Attached is the script and a .png of the output.
>
>
> ALSO, I would like to display land in gray with a black shoreline. Isn't
> there an easy way to accomplish this?

See my 1st email. The black shoreline should be there by default. If
not, set mpOutlineDrawOrder = "PostDraw". As you are wanting to fill the
land _after_ you fill your data, you must tell NCL to draw the map fill
last via mpFillDrawOrder = "PostDraw"...
Adam

>
> Thanks, again,
> gerry
>
> On 09/15/2011 01:57 PM, Adam Phillips wrote:
>> Hi Gerry,
>> I see you are using gsn_csm_contour as opposed to gsn_csm_contour_map..
>> (I didn't recognize this yesterday when I sent my original reply.) Are
>> you doing that on purpose? If so, then you can simply set vpWidthF and
>> vpHeightF to whatever values you wish between 0 and 1.
>>
>> If not, and you meant to use gsn_csm_contour_map, then the aspect ratio
>> will depend on the map projection you are using. By default the
>> projection is cylindrical equidistant. If you want to change the aspect
>> ratio when using one of the gsn_csm_*_map* routines, beyond setting
>> vpWidthF and vpHeightF, you also need to set mpShapeMode = "FreeAspect"
>>
>> Hope that helps..
>> Adam
>>
>> On 09/15/2011 12:43 PM, Gerald Creager wrote:
>>> Hit Send too fast. That did, in fact, cure the problem. Thanks for the
>>> gentle reminder.
>>>
>>> Now, an aesthetics problem: The plot looks "squished" horizontally. Is
>>> there a suggested aspect ratio I could set?
>>>
>>> On 09/15/2011 08:16 AM, Gerald Creager wrote:
>>>> Argh... No, Adam, it doesn't:
>>>>
>>>> printVarSummary(model1Ssh)
>>>>
>>>> Variable: model1Ssh
>>>> Type: float
>>>> Total Size: 37677960 bytes
>>>> 9419490 values
>>>> Number of Dimensions: 3
>>>> Dimensions and sizes: [90] x [261] x [401]
>>>> Coordinates:
>>>> Number Of Attributes: 1
>>>> _FillValue : -9999
>>>>
>>>>
>>>> On 09/14/2011 04:56 PM, Adam Phillips wrote:
>>>>> Hi Gerry,
>>>>> Does your model1Ssh array have associated latitude/longitude
>>>>> coordinate
>>>>> variables? You can see if it does by using printVarSummary:
>>>>> printVarSummary(model1Ssh)
>>>>>
>>>>> You should see something like this:
>>>>>
>>>>> Variable: model1Ssh
>>>>> <snip>
>>>>> Coordinates:
>>>>> time: [17067072..17618592]
>>>>> lat: [90..-90]
>>>>> lon: [ 0..357.5]
>>>>> (Last 3 lines show the coordinate variables.)
>>>>>
>>>>> If coordinate variables aren't present, you need to assign them.
>>>>> Looking
>>>>> at your script though, I see you are doing this:
>>>>> model1Ssh=100 * model1->sea_surface_height_above_sea_level
>>>>> This will result in only the data being passed from the right-hand
>>>>> side
>>>>> of the equal sign to the left-hand side, and not the coordinate
>>>>> variables associated with sea_surface_height_above_sea_level array.
>>>>>
>>>>> I'd recommend changing this:
>>>>> model1Ssh=100 * model1->sea_surface_height_above_sea_level
>>>>> to this:
>>>>> model1Ssh=model1->sea_surface_height_above_sea_level
>>>>> model1Ssh = model1Ssh*100
>>>>>
>>>>> I would venture to guess that that will fix your coordinate variables,
>>>>> and therefore the lats/lons shown on your plot...
>>>>>
>>>>> As far as the land mask issue: As you are plotting SSH there is no
>>>>> data
>>>>> over land, so those areas are getting color filled white. You need to
>>>>> tell NCL to color fill the map after the contour field gets color
>>>>> filled. Try setting res@mpFillDrawOrder = "PostDraw", and set
>>>>> res@mpLandFillColor = "gray70", as you are adding gray70 to your
>>>>> colormap, and it's best to exactly specify the color your want NCL to
>>>>> use.
>>>>>
>>>>> Let the group know if that doesn't solve everything..
>>>>> Adam
>>>>>
>>>>> On 09/14/2011 03:34 PM, Gerald Creager wrote:
>>>>> -------- Original Message --------
>>>>> Subject: Converting axis coordinates
>>>>> Date: Wed, 14 Sep 2011 16:34:13 -0500
>>>>> From: Gerald Creager<gerry.creager@tamu.edu>
>>>>> Reply-To: gerry.creager@tamu.edu
>>>>> Organization: AATLT, Texas A&M University
>>>>> To: ncl-talk@ucar.edu<ncl-talk@ucar.edu>
>>>>>
>>>>> I'm creating an image of a model output (attached), and the X and Y
>>>>> coordinates are currently in model indices. I'd like to have them
>>>>> represented as Lon/Lat.
>>>>>
>>>>> Also, I tried to create a gray landmask but it didn't seem to work. If
>>>>> someone's got a suggestion for that, I'd appreciate it. The ncl script
>>>>> is also attached.
>>>>>
>>>>> Thanks, gerry
>>>>
>>>
>>
>

-- 
______________________________________________________________
Adam Phillips                                asphilli@ucar.edu
NCAR/Climate and Global Dynamics Division       (303) 497-1726
P.O. Box 3000				
Boulder, CO 80307-3000    http://www.cgd.ucar.edu/cas/asphilli
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