Grids
GridSnapshots read at construction from a directory of NetCDF or GRIB files sharing the same variable and latitude/longitude grid. Each file must hold a {time, latitude, longitude} variable, with its dimensions in any order; axes are sorted ascending, longitudes beyond 180° (e.g., stored in [0, 360)) are moved to [-180, 180], and missing values become Double.NaN. Grids crossing the antimeridian are not supported, as they would split into two blocks with a gap in between. Files with no time axis are timed by their reference time axis, if any, with a warning: for forecasts, the reference time precedes the time the data are valid at by their lead time. When files share an instant, the first file in lexicographic order wins.
Parameters
the directory holding the data files, among the classpath resources or, if not there, on the file system.
the name of the variable inside the files (e.g., dis24), auto-detected when null.
Throws
if the directory does not exist or has no data files, if the variable is missing or ambiguous, or if the files disagree on their grid or variable.