[ncl-talk] getind_latlon2d with rectilinear grid

Dennis Shea shea at ucar.edu
Thu Sep 18 17:05:08 MDT 2014 

Ummm ... You did not try anything. You just reformatted  and forwarded the
question.
The whole point was for *you* do to something. That is how you learn.

I am responding because I don't want others to have to spend time and
effort.





On Thu, Sep 18, 2014 at 4:37 PM, Jiaxin Zhang <jiaxinzhang3 at gmail.com>
wrote:

> Dear NCL users,
>
> I am trying to extract variable values in some grids in specific locations
> for different times.
>
> I am attaching the NCL script that Dennis kindly provided to extract the
> values for 3 grids and 1 time only. The attached NCL script works well with
> the attached file "cVeg_CanESM2_1time.nc" that only contains 1 time. But I
> am having problems when I try to run the same script for the attached file
> "cVeg_CanESM2_12months.nc" that contains variable values for 12 times.
> After modifying the script to include time as dimension when reading the
> input file, I am getting error messages. I guess I am missing something but
> I can not figure out what is wrong.
>
> Could you please modify the attached script so that it works with the file
> "cVeg_CanESM2_12months.nc"?
>
> Your help is very appreciated!
> Many thanks in advance!
>
> Jiaxin
>
> 2014-09-18 13:22 GMT-07:00 Dennis Shea <shea at ucar.edu>:
>
> I'll respond here but I am quite busy and just can not answer multiple
>> questions.
>>
>> Perhaps someone else can chime in?
>>
>> [1] The original file you provided had no explicit time dimension.
>>      The 'time' was includes as an attribute of the variable.
>>      Note that there are no attributes (eg: hours since ) associated with
>> the time attribute.
>>      Actually, I believe that netCDF does not allow an attribute (here
>> 'time') to have
>>      have an attribute.
>>
>> [2] In this case it is *user* responsibility to manually create a time
>> dimension.
>>      It is user responsibility to manually provide this information. It
>> is not on the file.
>>
>> See attached
>>
>> **Please respond to ncl-talk only. Do not include a salutation to any
>> individual. Thank You**
>>
>>
>> On Wed, Sep 17, 2014 at 5:50 PM, Jiaxin Zhang <jiaxinzhang3 at gmail.com>
>> wrote:
>>
>>> Thank you so much, Dennis!
>>> This works perfectly!
>>>
>>> I just have a couple of questions. I am trying to do this for different
>>> times using the attached script and data file (for 12 months). For
>>> simplicity, in the attached script I am testing for only one site (instead
>>> of 3 sites). Although the script apparently extracts the variable values
>>> for that grid in all 12 times, I guess there are some errors in the script
>>> because the new netcdf created with the extracted variable values does not
>>> have the time variable. What is necessary to modify in the attached script
>>> so that the original time information is copied in the new created netcdf?
>>>
>>> Another issue I noticed is that when extracting variable values from 3
>>> sites (3 grids) at the same time and after that creating a new netcdf,
>>> apparently the new netcdf has only the lat and lon for the last site but
>>> not for the rest of the extracted sites. Would it be possible to keep the
>>> lat and lon information for all the sites from the original file in the new
>>> created netcdf?
>>>
>>> Thank you!
>>>
>>> Jiaxin
>>>
>>>
>>> 2014-09-17 5:57 GMT-07:00 Dennis Shea <shea at ucar.edu>:
>>>
>>>> Using getind_latlon2d should have failed. The 1st two arguments are
>>>> prototyped as 2-dimensional. You are inputting one-dimensional arrays.
>>>>
>>>>
>>>> 	function getind_latlon2d (
>>>> 		lat2d [*][*] : numeric,     <=== you are inputting lat[*]
>>>> 		lon2d [*][*] : numeric,     <===                   lon[*]
>>>> 		lat      [*] : numeric,
>>>> 		lon      [*] : numeric
>>>> 	)
>>>>
>>>> ==========
>>>> Let NCL do it
>>>>
>>>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>>>>
>>>>     diri = "/Users/shea/Downloads/"
>>>>     fili = "cVeg_CanESM2_1time.nc"
>>>>     pthi = diri+fili
>>>>     fi   = addfile(pthi,  "r")
>>>>    ;print(fi)
>>>>
>>>>     latpt = (/ 42.5, 25.4, 35.0 /)
>>>>     lonpt = (/-72.2,-81.1,-84.3 /)
>>>>     lonpt = where(lonpt.lt.0, lonpt+360, lonpt)
>>>>     npt   = dimsizes(latpt)
>>>>
>>>>     cVegpt= new ( npt, getfilevartypes(fi, "cVeg"), 1e20)
>>>>
>>>>     do np=0,npt-1
>>>>        cVegpt(np) = fi->cVeg({latpt(np)},{lonpt(np)})
>>>>     end do
>>>>     print(cVegpt)
>>>>
>>>>
>>>> On Tue, Sep 16, 2014 at 1:29 PM, Jiaxin Zhang <jiaxinzhang3 at gmail.com>
>>>> wrote:
>>>>
>>>>> Dear NCL users,
>>>>>
>>>>> I am trying to follow the example provided for getind_latlon2d in:
>>>>>
>>>>>
>>>>> http://www.ncl.ucar.edu/Document/Functions/Contributed/getind_latlon2d.shtml
>>>>>
>>>>> My data is in a rectilinear grid that can be completely described by
>>>>> one dimensional lat and lon arrays, whereas getind_latlon2d requires 2d
>>>>> arrays for lat and lon. How can I solve this problem? Is it better to use a
>>>>> different function from getind_latlon2d for 1d lat and lon arrays?
>>>>>
>>>>> I am attaching my NCL script and my file. I have 3 different sites
>>>>> (with given coordinates in attached script), that I would need to locate in
>>>>> the data grid. After that I would need to extract the value in that
>>>>> particular location (extract only the value of the 3 grids that contain the
>>>>> 3 sites). I was using getind_latlon2d to locate the 3 points in the data
>>>>> grid, but maybe there is better option to do that for rectilinear grids.
>>>>>
>>>>> Your help is very appreciated.
>>>>> Thank you!
>>>>>
>>>>> Jiaxin
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> ncl-talk mailing list
>>>>> List instructions, subscriber options, unsubscribe:
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>>>>>
>>>>>
>>>>
>>>
>>
>
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