[ncl-talk] Assign lat lon cordinates to polar stereographic coordinate
Dennis Shea
shea at ucar.edu
Tue Sep 13 08:11:47 MDT 2016
See:
http://www.ncl.ucar.edu/Document/Functions/Contributed/getind_latlon2d.shtml
and/or
http://www.ncl.ucar.edu/Document/Functions/Contributed/region_ind.shtml
Then
http://www.ncl.ucar.edu/Document/Functions/Built-in/wgt_areaave2.shtml
Ideally, the weights (areas represented by each grid point) would be
available in 'some file.' Or, perhaps you could construct them
or, perhaps, just use
wgt2d = cos(rsd*lat2d) ; rad converts degrees to radians
Good luck
On Tue, Sep 13, 2016 at 2:19 AM, Guido Cioni <guidocioni at gmail.com> wrote:
> Also make sure to perform the short to float conversion before working
> with your data!!!
>
> http://www.ncl.ucar.edu/Document/Functions/Contributed/short2flt.shtml
>
> Guido Cioni
> http://guidocioni.altervista.org
>
> On 13 Sep 2016, at 10:15, Guido Cioni <guidocioni at gmail.com> wrote:
>
> Assuming from your filedump you do have coordinate variables associated,
> so the following should easily work.
>
> temp_avg=dim_avg_n_Wrap(temp(:,:,{40:50},{-30:-10}),(/2,3/))
>
> Otherwise you would have to convert the latitude/longitude variables from
> 2D to 1D, use the ind function to find all the indices that map into your
> box, convert again into 2D indices with ind_resolve, subset temp with these
> indices, do the average.
>
> Guido Cioni
> http://guidocioni.altervista.org
>
> On 13 Sep 2016, at 09:10, Sourav Chatterjee <srvsxc at outlook.com> wrote:
>
> Thanks alot Mary for the explanation.
>
> Actually I need to do some area averaging for which I have the lat lon
> information e.g say, surface temperature averaged over 40-50N and -30:-10E.
> How to perform this spatial averaging with this temperature(time,depth,y,x)
> variable?
>
> Thanks
> Sourav
> ------------------------------
> From: Mary Haley <haley at ucar.edu>
> Sent: 12-09-2016 23:38
> To: Sourav Chatterjee <srvsxc at outlook.com>
> Cc: ncl-talk at ucar.edu
> Subject: Re: [ncl-talk] Assign lat lon cordinates to polar stereographic
> coordinate
>
> Sourav,
>
> I'm not sure what you mean by "converting my variable".
>
> Since your latitude and longitude arrays are two-dimensional, you cannot
> associate them with "temperature" in the same way that "y" and "x" are
> currently associated with "temperature" as coordinate variables. This is a
> NetCDF limitation that requires that coordinate variables be
> one-dimensional and the same length as the dimension they represent.
>
> You already have a "coordinates" *attribute* associated with
> "temperature", that indicates which variables represent the lat/lon arrays
> for your data:
>
> temperature:coordinates = "longitude latitude" ;
>
> This is how we would normally suggest that you "associate" 2D lat/lon
> arrays with a variable on a NetCDF file, so really, your "temperature"
> variable looks pretty good as it is.
>
> --Mary
>
>
> On Fri, Sep 9, 2016 at 4:19 AM, Sourav Chatterjee <srvsxc at outlook.com>
> wrote:
>
>> Hi all
>>
>>
>> I want convert my variable (temperature) to temperature
>> (time,depth,lat,lon) from temperature(time,depth,x,y)
>>
>>
>>
>> here is how it looks like now.
>>
>>
>> Any help!
>>
>>
>> Thanks
>>
>>
>>
>> dimensions:
>> depth = 12 ;
>> time = UNLIMITED ; // (288 currently)
>> x = 428 ;
>> y = 403 ;
>> variables:
>> int stereographic ;
>> stereographic:grid_mapping_name = "polar_stereographic" ;
>> stereographic:latitude_of_projection_origin = 90. ;
>> stereographic:longitude_of_projection_origin = -45. ;
>> stereographic:scale_factor_at_projection_origin = 1. ;
>> stereographic:straight_vertical_longitude_from_pole = -45. ;
>> stereographic:false_easting = 0. ;
>> stereographic:false_northing = 0. ;
>> float x(x) ;
>> x:axis = "X" ;
>> x:standard_name = "projection_x_coordinate" ;
>> x:units = "100 km" ;
>> float y(y) ;
>> y:standard_name = "projection_y_coordinate" ;
>> y:axis = "Y" ;
>> y:units = "100 km" ;
>> float depth(depth) ;
>> depth:long_name = "depth" ;
>> depth:units = "m" ;
>> depth:standard_name = "depth" ;
>> depth:positive = "down" ;
>> depth:axis = "Z" ;
>> double time(time) ;
>> time:units = "hour since 1950-1-1T00:00:00Z" ;
>> time:long_name = "forecast time" ;
>> float longitude(y, x) ;
>> longitude:standard_name = "longitude" ;
>> longitude:units = "degrees_east" ;
>> float latitude(y, x) ;
>> latitude:standard_name = "latitude" ;
>> latitude:units = "degrees_north" ;
>> short temperature(time, depth, y, x) ;
>> temperature:_FillValue = -32767s ;
>> temperature:missing_value = -32767s ;
>> temperature:add_offset = 23.5 ;
>> temperature:scale_factor = 0.000808839239385893 ;
>> temperature:units = "Celsius" ;
>> temperature:standard_name = "sea_water_potential_temperature" ;
>> temperature:grid_mapping = "stereographic" ;
>> temperature:coordinates = "longitude latitude" ;
>> temperature:cell_methods = "area: mean" ;
>>
>> // global attributes:
>> :title = "Arctic Ocean Physics Reanalysis (1991-2014), 12.5km
>> monthly mean (dataset-ran-arc-myoceanv2-be)" ;
>> :institution = "NERSC, Thormoehlens gate 47, N-5006 Bergen,
>> Norway" ;
>> :history = "20160112:Created by program hyc2proj, version V0.3" ;
>> :source = "NERSC-HYCOM model fields" ;
>> :references = "http://topaz.nersc.no" ;
>> :field_type = "Files based on file type nersc_weekly" ;
>> :Conventions = "CF-1.4" ;
>> :field_date = "2014-11-15" ;
>> :bulletin_date = "2014-11-15" ;
>> }
>>
>>
>>
>> _______________________________________________
>> 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/20160913/8b64ffc7/attachment.html
More information about the ncl-talk
mailing list