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There are numerous problems with grids employed for remapping by ACME (and CESM) prior to 20150901. These problems arise from flaws or limitations in the geometry of grids supplied to the utility (typically ESMF_RegridWeightGen) that generates the weights that regridders apply to convert between the source and destination maps. All tested regridders correctly apply the weights they are supplied, and migrating to improved grids (and to mapfiles generated from those grids, e.g., by ESMF_RegridWeightGen or Tempest) automatically improves both the numerical accuracy and the data and metadata completeness and consistency of the files produced by the regridding procedure. None of the problems described below affect the accuracy of the model results on the native grid. The affected grids include all the FV (plain and staggered grids), Gaussian grids for spectral models, mapfiles produced from those grids, and all mapfiles employing bilinear interpolation. These improved The new grids improve the accuracy of diagnostics and the aesthetics of plots produced from regridded files.
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