[CF-metadata] hybrid height

From: Jonathan Gregory <j.m.gregory>
Date: Sun, 13 Nov 2005 20:50:24 +0000

Dear All

I believe that the current definition of the atmosphere hybrid height
coordinate in CF Appendix D is incorrect. To match what is used in the HadGEM1
model, the definition should be as below. Is anyone using the definition
which currently appears in the standard? If not I propose we should replace it.

Cheers

Jonathan


standard_name = "atmosphere_hybrid_height_coordinate"

Definition:

z(n,k,j,i) = a(k) + b(k)*orog(n,j,i)

where z(n,k,j,i) is the height above the geoid (approximately mean sea level)
at gridpoint (k,j,i) and time (n), orog(n,j,i) is the height of the surface
above the geoid at (j,i) and time (n), and a(k) and b(k) are the coordinates
which define hybrid height level k. a(k) has the dimensions of height and b(k)
is dimensionless.

The format for the formula_terms attribute is

formula_terms = "tau: var1 eta: var2 ztop: var3 zsurface: var4" formula_terms =
"a: var1 b: var2 orog: var3"

There is no dimensionless hybrid height coordinate. The hybrid height is best
approximated as a(k) if a level-dependent constant is needed.
Received on Sun Nov 13 2005 - 13:50:24 GMT