Dear Lars > integral_of_air_temperature_excess_wrt_time > "integral_of_Y_wrt_X" means int Y dX. The data variable should have an axis > for X specifying the limits of the integral as bounds. "wrt" means with > respect to. Air temperature is the bulk temperature of the air, not the > surface (skin) temperature. The air temperature excess is the air temperature > minus the air temperature threshold, where only positive values are included > in the integral. Its integral with respect to time is often called after its > units of "degree-days". > > And the corresponding change to the explanation of the standard_name > integral_of_air_temperature_deficit_wrt_time > > Furthermore, recalling your response to my recent question > (http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2016/058800.html) I > suggest that a sentence elaborating on the temperature threshold should be > included. You wrote > "The data variable of the integral should have a scalar coordinate variable > or a size-one coordinate variable with the standard name of > air_temperature_threshold, to indicate the threshold."
I think these changes would all be fine. > why does it have to be a scalar or size-one coordinate variable? If we > consider the practical example of heating degree-days the threshold may not > be the same over a large region (as is the case for Europe), in which case > one would like to have a two-dimensional threshold variable. That is an interesting question. We're regarding it as a coordinate i.e. it's an independent variable on which the data depends. Coordinate variables are one-dimensional. The situation you're thinking of is analogous to, for example, temperature at the tropopause. Unlike the surfaces of 10 km altitude, or 200 hPa pressure, "tropopause" can't be defined with a single-valued numeric coordinate, so for that reason we include the name of this surface in the standard name of the quantity e.g. tropopause_air_temperature. If you have a geographically varying air temperature threshold, is there a constant definition which is being applied to obtain it? Best wishes Jonathan _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
