This page is under construction...explanation and links will be added in the coming days and weeks...feedback welcome!
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1. ACME adopted flawed FV-style gridfiles that omitted a small strip of longitude to the east of Greenwich. This problem was identified independently by Charles Doutriaux and myself. For FV 129x256, this amounted to 0.2% of global area, that might appear as a gap or blank strip when plotted. Maps based on the flawed grids somehow reapportion area so that total area is conserved (4*pi sr), yet this necessarily redistributes weights from their true positions. This causes a mismatch between "area"- and "gw"- weighted statistics. The proper solution is to generate grids that center Greenwich here is to correct the grids to avoid gaps, in this case, to restore the longitude strip to the west of Greenwich in the first zonal gridcell, and to base maps on those grids. With these grids, the gap disappears and "area"- and "gw"-weighted statistics can agree to double-precision.
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The As of version 4.5.2, the netCDF Operator ncks generates SCRIP-format gridfiles for select grid types, including equi-angular, FV, and Gaussian rectangular latitude/longitude grids. Full documentation is at http://nco.sf.net/nco.html#grid. For convenience, we sumarrize that functionality here. Options pertinent to the grid geometry and metadata are passed to NCO via key-value pairs prefixed by "--rgr". Pass at least six key-value pair arguments to create a fully explicitly specified, well-annotated grid. The six arguments, and their corresponding keys in parentheses, are: grid title (grd_ttl), filename to write the grid filename to (grid), number of latitudes (lat_nbr), number of longitudes (lon_nbr), latitude grid type (lat_typ), and longitude grid type (lon_typ). Four other arguments (the NSEW bounding box) are necessary to construct regular regional (non-global) grids, but for now we focus on global grids.
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