Ag,
> I am grappling with it but keep coming up with problems in each
> representation. Has this problem been dealt with by other parts of the
> community previously? Have the Met Office produced inhouse software that can
> understand the analysis/forecast duality?
We've dealt with this problem as part of the old NUWG conventions:
http://www.unidata.ucar.edu/packages/netcdf/NUWG/
with this excerpt from a note explaining the convention:
... here's an example we are currently using in our ruc.cdl for the
output of the MAPS/RUC model:
dimensions:
record = UNLIMITED ; // (reference time, forecast time)
...
variables:
double reftime(record); // reference time of the model
reftime:long_name = "reference time";
reftime:units = "hours since 1992-1-1";
double valtime(record); // forecast time ("valid" time)
valtime:long_name = "valid time";
valtime:units = "hours since 1992-1-1";
...
:record = "reftime, valtime" ; // "dimension attribute" -- means
// (reftime, valtime) uniquely
// determine record
Here "reftime" and "valtime" are like ... coordinate reference
variables for the "record" dimension, and so should have attributes
named "dimension" with value "record". But the record dimension has
a global coordinate attribute "record" that names the two coordinate
reference variables, so this information is already represented.
The idea here was to be able to use the "record" dimension for representing
an ordered pair of times, (reference time, forecast time), so you could
model outputs for multiple reference times and multiple forecast times in a
single netCDF file with only one unlimited dimension. ...
this capability.
--Russ
Received on Thu Jun 12 2003 - 09:55:39 BST
