Dear CF-ers, The statistics mabs/mibs/mebs stand for "Maximum absolute value", "Minimum absolute value", and "Mean absolute value", respectively. They are similar to max/min/mean statistics, and they can be useful in characterizing data when one wants positive-definite metrics. mebs (unlike mean) does not allow positive and negative values to compensate eachother. Unlike rms, mebs not does weight outliers quadratically. NCO (version 4.4.8) implements mabs/mibs/mebs as fundamental statistics (like max/min/mean/rms), and annotates the cell_methods attribute of variables reduced by these statistics with the strings "maximum_absolute_value", "minimum_absolute_value", and "mean_absolute_value". I suggest CF adopt this, or some variant pursuant to discussion.
So I guess this is a request for discussion. The relevant portions of CF are http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/build/cf-conventions.html#cell-methods http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/build/cf-conventions.html#appendix-cell-methods The modifications that would be needed seem straightforward: mention mabs/mebs/mibs in the text and then enlarge the existing cell_methods table table by three rows. There appears to be an error in the draft 1.7 document. The sentence describing Appendix E (the cell-methods appendix) says "In the Units column, u indicates the units of the physical quantity before the method is applied." Actually the units column entries are valid _after_ the method is applied. Variance is the only method for which this currently matters. This can be addressed independently of the rest of the cell_methods suggestions proposed here. Best, Charlie -- Charlie Zender, Earth System Sci. & Computer Sci. University of California, Irvine 949-891-2429 )'( _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
