Richard,
You can do this. Assuming you are storing the time series for more than
one watershed, you would have something like this (I lifted this largely
from Sections 7.1 and 7.2 in the CF Conventions document):
dimensions:
time = -1;
sheds = 20;
npoly_verts = 2000; // This would be set to the maximum number of
vertices for any watershed.
variable:
float precip(time, sheds);
precip.cell_measures = "area: watershed_areas";
precip.cell_methods = "time area: sum"
precip.coordinates = "lat lon";
time(time);
time.axis = "T";
time.standard_name = "time";
time.units = "days since ?????";
time.bounds = "time_bnds";
float lon(cell); // This variable will contain a longitude to associate
with each watershed. Perhaps the center.
lon.standard_name = "longitude";
lon.units = "degrees_east";
lon.bounds = "watershed_lons";
float lat(cell); // This variable will contain a latitude to associate
with each watershed. Perhaps the center.
lat.standard_name = "latitude";
lat.units = "degrees_north";
lat.bounds = "watershed_lats";
float watershed_lons(cell, npoly_verts); // This variable will have the
bounding longitudes for each watershed.
watershed_lons._FillValue = -999.0; // Use this value for unused elements.
float watershed_lats(cell, npoly_verts); // This variable will have the
bounding latitudes for each watershed.
watershed_lats._FillValue = -999.0; // Use this value for unused elements.
float watershed_areas(cell); // This variable will have the area for
each watershed.
watershed_areas.standard_name = "area";
watershed_areas.units = "km2";
I have left lots of attributes out. I hope this helps.
Grace and peace,
Jim
On 9/19/14, 4:09 PM, Signell, Richard wrote:
Folks,
A colleague asked me if a time series of data associated with a
polygonal region (e.g. rainfall in a watershed) could be represented
in CF.
So two questions:
1. Any reason this could be represented as a simple time series with a
cell_bounds = lon_verts, lat_verts
lon_verts(npoly_verts), lat_verts(npoly_verts)
2. I see an approved ticket from 4 years ago
https://cf-pcmdi.llnl.gov/trac/ticket/64
with "editorial correction" changing cell_bounds to bounds.
Does that mean that CF1.6 we use "cell_bounds" but in CF1.7 we will
use "bounds"?
--
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NOAA's National Climatic Data Center <http://ncdc.noaa.gov/>
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