[CF-metadata] standard names

From: Jonathan Gregory <j.m.gregory>
Date: Fri, 14 Nov 2003 13:38:04 +0000

Dear Pieter

> 1. Should I use "sea_floor_depth [m]" for the depth of the sea bottom at
> time/place of measurement?

sea_floor_depth should be a positive number - it means the same as "depth of
the sea bottom/floor below the surface". We don't have a standard name for
height of the sea floor above the surface, which would be a negative number.

"depth" and "height" are relative to the surface. We have not yet needed to be
precise about what "surface" means over the sea, but I think local mean sea
level would be the appropriate definition, as you suggest. I will add this to
the explanatory comments.

>> 2. Should I use "sea_surface_elevation [m]" for the water level at
> time/place of measurement or just sea_level? And again the question about
> used datum.

sea_surface_elevation is defined to be the altitude of the surface above the
geoid. Is this what you mean by sea level? Do you mean the water level with
respect to mean sea level? We haven't got a name for this yet but we could
logically call it sea_surface_height, which is what that term sometimes means.

If you are interested in elevation and we need to define which geoid is used
we will have to do some more work. This is an area which we haven't
considered because it's not relevant for models.

> 3. Regarding water_velocity: I have found the following CF standard names:
> "eastward_sea_water_velocity [m s-1]"
> "northward_sea_water_velocity [m s-1]"
> "direction_of_sea_water_velocity [deg]"
> and
> "current_speed" in one of the examples (par 3.3 of 1.0 beta5).

current_speed is not a standard name. sea_water_speed is a standard name,
meaning the magnitude of the (vector) sea_water_velocity.

> If the cells are part of a curvilinear grid what variable should I use for
> cell boundary speeds (meaning the average speed at a cell boundary
> perpendicular to this boundary).

The velocity components relative to the local x- and y-directions on the grid
should be called grid_eastward_sea_water_velocity and
grid_northward_sea_water_velocity (as for winds). These standard names are not
in the table but I propose we should add them.

Best wishes

Jonathan
Received on Fri Nov 14 2003 - 06:38:04 GMT