cmip6dr / cmip7_forward_look

Collection of documents and issues for CMIP7 data request
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uqint and vqint : specific vs. absolute humidity. #59

Open martinjuckes opened 3 years ago

martinjuckes commented 3 years ago

uqint and vqint were introduced fir HighResMIP following an email in January 2017 to the CF standard name list requesting the terms: http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2017/008963.html.

They are related to the standard name "integral_wrt_height_of_product_of_eastward_wind_and_specific_humidity", with standard_name.description = "The phrase "integral_wrt_X_of_Y" means int Y dX. To specify the limits of the integral the data variable should have an axis for X and associated coordinate bounds. If no axis for X is associated with the data variable, or no coordinate bounds are specified, it is assumed that the integral is calculated over the entire vertical extent of the medium, e.g, if the medium is air the integral is assumed to be calculated over the full depth of the atmosphere. The phrase "wrt" means "with respect to". Height is the vertical distance above the surface. The phrase "product_of_X_and_Y" means X*Y. Wind is defined as a two-dimensional (horizontal) air velocity vector, with no vertical component. (Vertical motion in the atmosphere has the standard name "upward_air_velocity".) "Eastward" indicates a vector component which is positive when directed eastward (negative westward). Specific humidity is the mass fraction of water vapor in (moist) air."

The terms have units m2 s-1, but it is clear that weighting by air density is needed to make physical sense.