[gradsusr] Interpolation options in Grads In case of ocean data

[Jennifer M Adams]

The interpolation routines available with the lterp() function are fairly conservative, and will usually throw away a few data points around the perimeter of missing data — bilinear interpolation requires all four points, box averaging requires the grid box to be at least 50% populated with legitimate data values. If you want to invent data, you’ll also have to invent your own algorithm for doing it. Sorry! 
—Jennifer


> On Oct 19, 2019, at 8:42 PM, Subhajit Ghosh <subhajitghosh08 at gmail.com> wrote:
> 
> Hi everyone 
> I am using a global file .25deg resolution contains significant wave height value. now some of the data are missing and I like to do a interpolation to fill the gaps before making it to an image. Is there any option within grads with which I can do so.
> definition of the nc file pasted below :
> netcdf wvhgt {
> dimensions:
>         latitude = 721 ;
>         longitude = 1440 ;
>         time = UNLIMITED ; // (24 currently)
> variables:
>         double latitude(latitude) ;
>                 latitude:units = "degrees_north" ;
>                 latitude:long_name = "latitude" ;
>         double longitude(longitude) ;
>                 longitude:units = "degrees_east" ;
>                 longitude:long_name = "longitude" ;
>         double time(time) ;
>                 time:units = "seconds since 1970-01-01 00:00:00.0 0:00" ;
>                 time:long_name = "verification time generated by wgrib2 function verftime()" ;
>                 time:reference_time = 1568160000. ;
>                 time:reference_time_type = 3 ;
>                 time:reference_date = "2019.09.11 00:00:00 UTC" ;
>                 time:reference_time_description = "forecasts or accumulated (including analyses), reference date is fixed" ;
>                 time:time_step_setting = "auto" ;
>                 time:time_step = 3600. ;
>         float WVHGT_surface(time, latitude, longitude) ;
>                 WVHGT_surface:_FillValue = 9.999e+20f ;
>                 WVHGT_surface:short_name = "WVHGT_surface" ;
>                 WVHGT_surface:long_name = "Significant Height of Wind Waves" ;
>                 WVHGT_surface:level = "surface" ;
>                 WVHGT_surface:units = "m" ;
> 
> // global attributes:
>                 :Conventions = "COARDS" ;
>                 :History = "created by wgrib2" ;
>                 :GRIB2_grid_template = 0 ;
> 
>  Image output is also attached herewith 
> 
> Thanks and regards 
> <in_wvhgt.png>_______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://secure-web.cisco.com/1DvhRtb4D6011Ho1OaTEWW-WOBMbsaFzSPhQFRo2ovgtMDW-u9iN6zEEzxUwoFyPkrXRaPjI_4omiAvLxaH64ZVGdT6r6C9LZhwO34vWV6h-ICgM4wnz-yrccpnIihepi7ism7XW0U7w9tnJIGuXeibjp5w-WggYuLl2R6ggpHlkyQQRxUgislONin2dhImGsZD8z0oL7zsbxiWeNaW7B_E75w9SK0-CpPHPdI_GCC4bcTZTHAI58MhR1wdYZJVp70Ipzh60gM8WZp7_IpfNKHhA0FKaUfSacKZ9o8t6AFr9NAHt4Bex04uv_l8Bd6AcGhcrOOFqlV03yNVmWa0Gk-aCP9TpndlMt93rzBNqm-6Tq-KDP2u6B5KnhBemBDdJKWDn16Zic7Qf59863Y51dNbeVYfxtrSt8UMlxwWIw3Yb12pYimbJAFkbVVfRk79st/http%3A%2F%2Fgradsusr.org%2Fmailman%2Flistinfo%2Fgradsusr

--
Jennifer Miletta Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
George Mason University