For example, suppose you have been given a 0. The first gaussian grid number. The function re offers many transform options ranging from simple bilinear interpolation to box averaging with voting. The default value of 0. Any valid GrADS grid expression e.
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[gradsusr] Regridding in GrADS
The parameter vtmin must be the same as vtmax except for three or regrod candidates. The above three regrid commands produce exactly the same results. Vote interpolation or box averaging with voting. The first gaussian grid number.
Missing values will be filled for the uncovered regions. It is generally recommended that you use the bessel option when interpolating because the higher-order terms in the polynomial interpolation function produce a closer fit to the original data in regions of rapid changes e.
It is strongly suggested to use lats4d or fwrite to write your results to a disk file, and then visualize your results afterwards. Second, an undefined value in the 2×2 bilinear stencil causes the output grid to be undefined.
GrADS will draw the grid box and color it according to the grid value. Suppose you regrid a T62 global Gaussian grid x94 to a uniform 2. The first step in the regrid transform is to define a relationship between the input and output grids within a common frame of reference or coordinate system. If a valid transform cannot be made i. Box averaging would be more appropriate when regridding to a coarser grid.
Otherwise, the bessel interlopation is used. Otherwise the output grid box is set to undefined. The boundaries for gaussian grids can be calculated by specifying ig XXX in options. Input grid is gaussian with nyig being the number of gaussian latitudes e.
During candidate selection, undefined input grid points do not contribute to the fraction of the output grid box covered with input grid boxes. Regridd default value of 0. In this new syntax, the size and gradz locations of output grids can be exactly described.
The intuitive solution is to assign the output grid the value of the intersecting input grid box es which account s for the greatest percentage of the output grid box surface area. By default the boundaries are assumed to lie midway between grid points and while this is not strictly true for a gaussian grid near the poles, it is degrid nonetheless.
The porting was done with the utility f2c to convert original f77 code to C, and the resulting C code was modified to eliminate the dependency on the f2c library.
This feature is useful when using fwrite to create binary files. This parameter is used to invoke a more precise calculation of the boundary between gaussian grid boxes.
[gradsusr] Regridding in GrADS
Despite this restriction on grid coordinates, you can access regriv chunks of a regridded defined variable using world coordinates. The parameters vtmax,vtmin range: Any valid GrADS grid expression e. Regrid 1×1 Aviation run mb z to 2. Perhaps the most conventional way of regridding meteorological data e.
The best way to understand this is by an example. The function was renamed from regrid to reand the regfid were reorganized to a syntax that closely followed the conventions used by the standard GrADS file descriptor. If the bilinear value is defined, but any of the points in the larger 4×4 bessel stencil are undefined, the output grid is assigned the bilinear value.
As regfid above, the world-grid mapping in GrADS is one-dimensional. The reason why this cannot be automatic is that GrADS does not directly support gaussian grids i.
This approach is most appropriate: