[CF-metadata] Standard name - Stomatal resistance

From: Pamment, JA <J.A.Pamment>
Date: Thu, 6 Jul 2006 14:12:32 +0100

This is a continuation of the discussion of the proposal for new standard names for
stomatal_resistance; Maximum stomatal resistance; s m-1
stomatal_resistance; Minimum stomatal resistance; s m-1
received from Beate Geyer. I have moved it from the main thread of "Geyer and Ruane standard names" because I think this may need wider discussion.

Below is a summary of what has been said so far on this proposal:
Beate wrote:
> stomatal resistance depends on vegetation type, it is not clear
> to me, how to include min and max into standard name:
> stomatal_resistance; Maximum stomatal resistance; s m-1
> stomatal_resistance; Minimum stomatal resistance; s m-1

Jonathan wrote:
> I suppose this could be indicated by cell_methods "vegetation_type:
> maximum".
> We have not got standard names for stomatal resistance and vegetation type.
> Are you proposing these?

Beate wrote:
> A: Yes, stomatal_resistance is the proposal.
> Each vegetation type has its maximum and its minimum, depending on the situation
> (water supply and temperature).

Alison wrote:
> I have spoken to Jonathan about this proposal and realised that he and I were placing
> different interpretations on what is being requested. If you wish to represent the
> maximum and minimum values of stomatal resistance occurring within a model grid box
> containing a number of different vegetation types then Jonathan's idea of using
> cell_methods would seem the logical way to go. If, however, you are wishing to describe the range of values that stomatal resistance may take as a function of vegetation type
> then this may be better specified using a standard name modifier. Please can you
> clarify which of these interpretations is correct?

Beate wrote:
> yes, I wish to 'describe the range of values that stomatal resistance may take as a
> function of vegetation type'

Below I have used a CDL example to explain how I think max and min stomatal resistance as a function of vegetation type could be represented. I would welcome comments on this, especially if anyone thinks there is a more straightforward approach.

My approach requires the definition of two new standard names:
stomatal_resistance (sm-1) and vegetation_cover. The latter would be a string or would use flags to indicate vegetation type in a way similar to land_cover and surface_cover which are already in the standard name table. Two new standard name modifiers would also need to be defined: max and min. The idea is to use vegetation type as a dimension along with latitude, longitude and time. I think that this would allow for multiple vegetation types within a grid cell, and each type could have its own max and min stomatal resistance according to the temperature and water conditions within the cell.

dimensions:
  vegtype=3 ; //no. of vegetation types
  max_len_veg_name=64 ;
  lat=180 ;
  lon=360 ;
  time=UNLIMITED ;
variables:
  float stomatal_resistance(time,lat,lon,vegtype) ;
    stomatal_resistance:standard_name="stomatal resistance" ;
    stomatal_resistance:units="sm-1" ;
    stomatal_resistance:coordinates="veg_name" ;
    stomatal_resistance:ancillary_variables="max_stom_res min_stom_res" ;
  float max_stom_res(time,lat,lon,vegtype) ;
    max_stom_res:standard_name="stomatal_resistance max" ;
    max_stom_res:units="sm-1" ;
    max_stom_res:coordinates="veg_name" ;
  float min_stom_res(time,lat,lon,vegtype) ;
    min_stom_res:standard_name="stomatal_resistance min" ;
    min_stom_res:units="sm-1" ;
    max_stom_res:coordinates="veg_name" ;
  double time(time) ;
    time:long_name="time" ;
    time:units="days since 1990-1-1 0:0:0" ;
  float lat(lat) ;
    lat:long_name="latitude" ;
    lat:units="degrees_north" ;
  float lon(lon) ;
    lon:long_name = "longitude" ;
    lon:units = "degrees_east" ;
  char veg_name=(vegtype,max_len_veg_name) ;
    veg_name:standard_name="vegetation cover" ;
data:
  veg_name="needleleaf", "deciduous", "grass" ;

------
Alison Pamment??????????????????????????? Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre????? Fax: +44 1235 445858
Rutherford Appleton Laboratory??????????? Email: J.A.Pamment at rl.ac.uk
Chilton, Didcot, OX11 0QX, U.K.
 
Received on Thu Jul 06 2006 - 07:12:32 BST