[ncl-talk] Longitude Flip in ocean data
Mary Haley
haley at ucar.edu
Fri Jan 22 11:00:43 MST 2016
You created a "var1" array when calling lonPivot, but then you are still
plotting the original "var" array. Change "var" to "var1" in this call:
plot =
gsn_csm_contour_map(wks,var(time_cell,0,minlocY:maxlocY,minlocX:maxlocX),res)
; create plot
On Fri, Jan 22, 2016 at 2:25 AM, Arun Kumar Dwivedi <
dwivedi.arunkumar at gmail.com> wrote:
> Dear All,
> In continution to our previous query and according to the suggestions
> given, LonPivot function is used and the longitude array was reassigned
> from -180 to 180 after LonPivot, but still there is a problem with the
> output plot. Attached is our output file and the modified script.
> The variable summary before LonPivot and After LonPivot is given below.
>
> *Before assigning*
> Variable: var
> Type: float
> Total Size: 4499840 bytes
> 1124960 values
> Number of Dimensions: 4
> Dimensions and sizes: [T1 | 20] x [ZT_K1_1 | 1] x [YT_J | 178] x [XT_I
> | 316]
> Coordinates:
> T1: [1005606..1005720]
> ZT_K1_1: [ 2.5.. 2.5]
> YT_J: [ -79.. 79]
> XT_I: [ 1.. 359]
> Number Of Attributes: 4
> missing_value : -1e+34
> _FillValue : -1e+34
> long_name : Sea Surface Temperature
> units : Deg C
>
>
> *AFTER LONPIVOT*
> Variable: var1
> Type: float
> Total Size: 4499840 bytes
> 1124960 values
> Number of Dimensions: 4
> Dimensions and sizes: [T1 | 20] x [ZT_K1_1 | 1] x [YT_J | 178] x [XT_I
> | 316]
> Coordinates:
> T1: [1005606..1005720]
> ZT_K1_1: [ 2.5.. 2.5]
> YT_J: [ -79.. 79]
> XT_I: [-179.. 179]
> Number Of Attributes: 5
> missing_value : -1e+34
> _FillValue : -1e+34
> long_name : Sea Surface Temperature
> units : Deg C
> lonPivot : reordered via lonPivot [NCL]: pivotLon=181
>
> Thanks & Regards
> Arun Kumar Dwivedi
> Mob :09546189035
>
> On Fri, Jan 22, 2016 at 1:29 AM, Mary Haley <haley at ucar.edu> wrote:
>
>> Arun,
>>
>> The issue is that "lonFlip" is expecting the "180" point to be exactly
>> halfway in your longitude array. We need to update the documentation to
>> indicate this.
>>
>> Your longitude values don't jump to 181 until more than halfway through
>> the array, so this is why lonFlip was failing.
>>
>> You can use lonPivot to do what you want:
>>
>> var = in->$ip$
>> var = lonPivot(var,181)
>> printVarSummary(var)
>>
>> To make sure that you are referencing the correct latitudes and
>> longitudes afterwards, you want to set xlat and xlon to the arrays that are
>> attached to "var", instead of reading them off the file:
>>
>> xlat = var&YT_J
>> xlon = var&XT_I
>>
>> These changes should get you the plot you want.
>>
>> -Mary
>>
>>
>> On Tue, Jan 19, 2016 at 9:28 PM, Arun Kumar Dwivedi <
>> dwivedi.arunkumar at gmail.com> wrote:
>>
>>> Dear All,
>>> As discussed earlier, We have uploaded our nc file and our script in the
>>> ftp server. Our requirement is to plot a parameter for Atlantic and Indian
>>> ocean (For eg -90W to 100E and from -50S to 50 N).. And our resultant
>>> output is also attached where in the plot is only until 0E.
>>>
>>> NOTE: We are taking our inputs from a dat file which is also attached
>>> here (mom-ctrl-slc.dat)
>>>
>>> Data File Name--Forecast201510040000.nc
>>> Input control File Name --mom-ctrl-slc.dat
>>> Script Name-- mom-slc.ncl
>>> Our output Name-- mom_slc_TEMPNEW_2015100612UTC.png
>>>
>>> Thanks & Regards
>>> Arun Kumar Dwivedi,
>>> Project Engineer - II
>>> Computational Earth Science Group
>>> CDAC, Pune - 411 007
>>> Mob :09546189035
>>>
>>> On Sat, Jan 16, 2016 at 2:13 AM, Mary Haley <haley at ucar.edu> wrote:
>>>
>>>> Can you provide me with the data file so I can test this here? It
>>>> looks like the longitude values should be flipping correctly, but I don't
>>>> understand why you are getting values from -257.75 to 101.75.
>>>>
>>>> The longitude array must be monotonically increasing for this to work,
>>>> I believe, but I want to check the array myself to see what's going on with
>>>> it.
>>>>
>>>> If your file is too large, then if you could just write sst to the file
>>>> by itself, and send me that, then I don't need anything else.
>>>>
>>>> You can write sst to a file using the following code:
>>>>
>>>>
>>>> system("rm marytest.nc")
>>>> mout = addfile("marytest.nc","c")
>>>> mout->sst = sst
>>>>
>>>> You can upload the file to our ftp:
>>>>
>>>> http://www.ncl.ucar.edu/report_bug.shtml#HowToFTP
>>>>
>>>> or share it via Dropbox or Google Drive or something similar.
>>>>
>>>> Thanks,
>>>>
>>>> --Mary
>>>>
>>>>
>>>>
>>>> On Wed, Jan 13, 2016 at 12:40 AM, Arun Kumar Dwivedi <
>>>> dwivedi.arunkumar at gmail.com> wrote:
>>>>
>>>>> Dear all,
>>>>> Thank q for the response
>>>>> In continuation to my above query the description is given below
>>>>>
>>>>> Our data is rectilinear data ( data is in rectangular matrix with
>>>>> un-uniform spacing). '
>>>>>
>>>>> Our basic data structure is :
>>>>>
>>>>> Variable: sst
>>>>> Type: float
>>>>> Total Size: 4499840 bytes
>>>>> 1124960 values
>>>>> Number of Dimensions: 4
>>>>> Dimensions and sizes: [T1 | 20] x [ZT_K1_1 | 1] x [YT_J | 178] x
>>>>> [XT_I | 316]
>>>>> Coordinates:
>>>>> T1: [1005606..1005720]
>>>>> ZT_K1_1: [ 2.5.. 2.5]
>>>>> YT_J: [ -79.. 79]
>>>>> XT_I: [ 1.. 359]
>>>>> Number Of Attributes: 4
>>>>> missing_value : -1e+34
>>>>> _FillValue : -1e+34
>>>>> long_name : SST
>>>>> units : C
>>>>>
>>>>>
>>>>> ****************************
>>>>> Our actual problem is we need to plot longitude in the selected range
>>>>> for eg -90W to 120E then it doesnt accept the -90W value since the
>>>>> longitude array is from 0 to 360 , the plot comes from 0 to 120E only. (-ve
>>>>> values not accepted.) . To solve this we used lonflip function so that our
>>>>> longitude array changes from -180 to 180. but since it is un-uniform data ,
>>>>> ***********************************
>>>>> After LonFlip , it is
>>>>>
>>>>> Variable: sstnew
>>>>> Type: float
>>>>> Total Size: 4499840 bytes
>>>>> 1124960 values
>>>>> Number of Dimensions: 4
>>>>> Dimensions and sizes: [T1 | 20] x [ZT_K1_1 | 1] x [YT_J | 178] x
>>>>> [XT_I | 316]
>>>>> Coordinates:
>>>>> T1: [1005606..1005720]
>>>>> ZT_K1_1: [ 2.5.. 2.5]
>>>>> YT_J: [ -79.. 79]
>>>>> XT_I: [-257.75..101.75]
>>>>> Number Of Attributes: 5
>>>>> missing_value : -1e+34
>>>>> _FillValue : -1e+34
>>>>> long_name : SST
>>>>> units : C
>>>>> lonFlip : longitude coordinate variable has been reordered via
>>>>> lonFlip
>>>>>
>>>>> The longitude is originally from 0 to 360 and after LonFlip it is
>>>>> -257.75..101.75... But when we are plotting in the longitude range (-90,
>>>>> 120) it is coming only in the longitude range (-90, 101)
>>>>>
>>>>> So what would be the solution for our problem
>>>>>
>>>>>
>>>>>
>>>>> Thanks & Regards
>>>>> Arun Kumar Dwivedi,
>>>>> Project Engineer - II
>>>>> Computational Earth Science Group
>>>>> CDAC, Pune - 411 007
>>>>> Mob :09546189035
>>>>>
>>>>> On Tue, Jan 12, 2016 at 7:44 PM, Mary Haley <haley at ucar.edu> wrote:
>>>>>
>>>>>> Arun,
>>>>>>
>>>>>> We need a little more information here. Is your data on a
>>>>>> rectilinear grid? This function only works for rectilinear grids (grids
>>>>>> represented by 1D lat/lon arrays).
>>>>>>
>>>>>> Did you look at your longitude values to make sure there are no
>>>>>> issues with them before you do lonFlip?
>>>>>>
>>>>>> It would help if we could see a "printVarSummary" of the variable you
>>>>>> are trying to call lonFlip on, and also any error messages.
>>>>>>
>>>>>> --Mary
>>>>>>
>>>>>>
>>>>>> On Sun, Jan 10, 2016 at 11:10 PM, Arun Kumar Dwivedi <
>>>>>> dwivedi.arunkumar at gmail.com> wrote:
>>>>>>
>>>>>>> Dear All,
>>>>>>> I am working on ocean data (MOM and WAM) for global domain. I have
>>>>>>> issues with longitude, when trying to plot in for particular region. For eg
>>>>>>> if I want plot with Latitude 0 to 30 and Lon -40 to 100. Then it doesn't
>>>>>>> recognize the value -40 in the longitude array.
>>>>>>>
>>>>>>> For this i have tried using LonFlip function, it works fine with
>>>>>>> uniform grid but doesn't work with my data set which has varied grid
>>>>>>> resolution (0.5,1 and 1.5).
>>>>>>>
>>>>>>>
>>>>>>> Thanks & Regards
>>>>>>> Arun Kumar Dwivedi,
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> ncl-talk mailing list
>>>>>>> ncl-talk at ucar.edu
>>>>>>> List instructions, subscriber options, unsubscribe:
>>>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> ncl-talk mailing list
>>>>> ncl-talk at ucar.edu
>>>>> List instructions, subscriber options, unsubscribe:
>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>
>>>>>
>>>>
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> ncl-talk at ucar.edu
>>> List instructions, subscriber options, unsubscribe:
>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>
>>>
>>
>
> _______________________________________________
> ncl-talk mailing list
> ncl-talk at ucar.edu
> List instructions, subscriber options, unsubscribe:
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20160122/39b6e590/attachment.html
More information about the ncl-talk
mailing list