how to re-center spatial data (longitudes centered on 0) before grid interpolation?

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k78na 2016-6-22

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https://ww2.mathworks.cn/matlabcentral/answers/291742-how-to-re-center-spatial-data-longitudes-centered-on-0-before-grid-interpolation

回答： KSSV 2016-6-23

I would like interpolate a spatial data file (lat_old, long_old) to a different grid (lat_new, lon_new), where the grid size is different and latitudes are centered on zero.

I tried the following:

    [X,Y]=meshgrid(lon_old,lat_old);
    [X_new,Y_new]=meshgrid(lon_new,lat_new);
    data_new= interp2(X,Y,data_old',X_new,Y_new);

However, the old longitudes are (0,360), while the new grid is centered on 0 (-180,180). The code above only performs interpolation for the positive part of the new grid, and yields NaN for negative longitude values (-180,0). (Please note that grid sizes are also different, and the new grid is centered on longitude 0)

How do I re-center 'data_old' with longitude values (0,360) to (-180,-180), before performing the interpolation to a new grid size?

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Answer 1

KSSV 2016-6-23

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/291742-how-to-re-center-spatial-data-longitudes-centered-on-0-before-grid-interpolation#answer_226416

To change 0 to 360 grid to -180 to +180, you need not to interpolate. Check resolution between 0 to 360, take the same resolution from -180 to +180 and replace 0 to 360 with -180 to +180. Once you have done this, then you may go for interpolation to get the grid for any other resolution.