Table 4.15 https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_table4-15.shtml Data is calculated directly from the source grid with no interpolation (see note 1) Bilinear interpolation using the 4 source grid grid-point values surrounding the nominal grid-point Bicubic interpolation using the 4 source grid grid-point values surrounding the nominal grid-point Using the value from the source grid grid-point which is nearest to the nominal grid-point Budget interpolation using the 4 source grid grid-point values surrounding the nominal grid-point (see note 2) Spectral interpolation using the 4 source grid grid-point values surrounding the nominal grid-point Neighbor-budget interpolation using the 4 source grid grid-point values surrounding the nominal grid-point (see note 3) Missing