Hi Ted/All,
The initial requirement of the GN thredds harvester is to facilitate discovery
(and provide a tool that can be built on by others) - a user should be able to
determine whether there is data that suits their requirement out there (dataset
metadata) and then where it is (services that deliver it) - lots of other
things would be nice too but these are the basic requirements for the moment
(and its more than enough)....
In the 'facilitating discovery' context and using your example below, for plain
ISO19115: we're initially going to follow the approach taken in the DIF-to-ISO
converter of placing a subset of that info into gmd:keywords. Within our own
projects and IMOS we'd like to identify the vocabulary etc that these are taken
from if available (just as the DIF-to-ISO converter writes the GCMD keyword
vocabulary into the gmd:thesaurusName element in gmd:keywords). For the BlueNet
version of the Marine Community Profile of ISO19115
(http://bluenet3.antcrc.utas.edu.au/mcp) we have an extension element (named
mcp:dataParameters) that we will use for this type of data. Future work could
look at using the gmd:MD_CoverageDescription element eg. along the lines of the
C3Grid project for gridded data.
For metadata other than the attributes/variables/parameters, we can't harvest
what isn't there, so we'll harvest whatever we can in the same way as
threddsmetadata group elements are used to produce DIF (and other metadata
schemas) in netcdf-java (though we are not requiring all elements to be there
before a harvest can occur).
I know you (and your group) have been involved in this type of work for
sometime (we've had some discussions in the GeoNetwork area too on related
stuff!) so apologies if all of the above is a bit light - I hope we can
cooperate some more on the development of the harvester Ted!
Apologies to everyone else if this is starting to stray away from thredds....
Cheers,
Simon
________________________________________
From: Ted Habermann [Ted.Habermann@xxxxxxxx]
Sent: Tuesday, 14 April 2009 6:15 AM
To: Pigot, Simon (CMAR, Hobart)
Cc: Pauline.Mak@xxxxxxxxxxx; rsignell@xxxxxxxxx; thredds@xxxxxxxxxxxxxxxx;
Peter.Blain@xxxxxxxxxxx; NGDC Geospatial; Erin Robinson
Subject: What would the ISO metadata look like?
Simon et al.,
This is the second response inspired by the recent THREDDS discussion. This one
is more ISO focused. Assume that you connected to a THREDDS Server and were
ready to write an ISO metadata record. What would you actually write? I have
been trying to figure this one out for awhile and submitted this question to
EDEN. I would, of course, be interested in you answer as well as this is a very
common THREDDS Server case.
Thanks,
Ted
The grids are:
Attributes
Analysis Temperature: The latest Sea Surface Temperature calculated based on
the previous analysis temperature, weighted according to its reliability,
combined with a weighted average of current observations within a surrounding
area which is determined according to the grid point's gradient.
Average Gradient: The average of the gradients in all four directions (N, S, E,
W) from the grid intersection.
Gradient X+, X-, Y+, Y-: Gradients in various Directions.
Physiographic Descriptor: The land/sea tag indicating whether a grid
intersection is a land or sea point.
land_binary_mask (CF name for Physiographic Descriptor): X_binary_mask has 1
where condition X is met, 0 elsewhere. 1 = land, 0 = sea.
Ice Field: Percent sea ice for 50 km SST field.
Number Observations: Number of Observations - The total number of current
observations u e new temperature for the grid intersection.
Age Recent Observation: Age of Most Recent Observation - The age, in hours from
the time of last analysis, of the most recent observation used to determine the
new temperature for a grid intersection.
Reliability: New reliability associated with the new temperature, based on the
previous reliability combined with the weighted reliability of all observations
used in the last analysis.
Class 1 Coverage: Class 1 Temporal Coverage - Set of bits (0-15) of which bit 1
is set to 1 for each analysis which included observations with a reliability
greater than or equal to a specific minimum reliability considered as class 1.
Bit 0 always remains a 0, and all bits are shifted right during each analysis
leaving b reliability observations are used for a grid intersection.
Spatial Covariance X+, X-, Y+, Y-: The distance in grid units from the grid
intersection to the nearest land mass in a given direction.
Climatological Temperature: Independent Grid Temperature - The average sea
surface temperature of a grid intersection for a particular month over a number
of years, taken from the global climatology file.
==== Ted Habermann ===========================
Enterprise Data Systems Group Leader
NOAA, National Geophysical Data Center
V: 303.497.6472 F: 303.497.6513
"If you want to go quickly, go alone.
If gether"
Old Proverb
==== Ted.Habermann@xxxxxxxx<mailto:Ted.Habermann@xxxxxxxx> ==================
