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Ben, Thanks for writing this good start. I for one would like some more detailed information about the listed types of data: 1) Which type(s) of ISO 19123 coverage is this? 2) What domain dimensions are needed? 3) What range data structures are needed (called fields and axes in WCS 1.1)? 4) What are the relative priorities among these types of data? Arliss
From: Ben Domenico
Sent: Wednesday, January 30, 2008 9:42 AM
To: Unidata GALEON; WCS. RWG
Subject: [WCS.RWG] Use Case for High Res Weather Forecast Model Data Services
Hi,
One of my action items resulting from last week's WCS.SWG was to
contribute use cases representing the needs of the GALEON community. Of
course there are many such use cases and they can be described in
several ways. I have chosen a scenario that embodies the great variety
of data types required, a need for real-time access, and a situation in
which the use depends on having the data in the full 3 spatial
dimensions as well as several time lines: observation times, model run
times, and the times the forecasts apply.
I have attempted to describe the use case in terms that a non-expert,
end user of the system, can understand. But I realize that it may
eventually need to be translated into the language of the standards
community. My sense is that it will end up being many use cases at that
point and will perhaps lose some of the coherence it has in this form.
My hope is that this will be a useful starting point for discussion and
will stimulate more and better GALEON-related use cases.
Your comments, corrections, and suggestions will be greatly appreciated.
-- Ben
Outline of Coverages Use Case for High Res Weather
Forecast Models
Draft by Ben Domenico
To improved air traffic efficiency and safety, an organization wants to
assemble the data needed to run high resolution local weather forecast
models for the region surrounding an airport and to serve the input data
as well as the output of the forecast model. The goal is to base the
data services for both input and output datasets on standard data
models, interfaces, and protocols wherever possible.
On the input side, this includes real-time data from a wide variety of
sources and many different types:
-- point data from lightning strike observations
-- "station" observations from fixed weather stations in the region
-- vertical profiles from nearby balloon soundings and wind profilers
-- trajectory data obtained from other aircraft which have taken off and
landed recently
-- volumetric scans from ground-based radars
-- visible, infrared, and water-vapor (and possibly other wavelength)
satellite imagery
-- gridded output from national or hemispheric weather forecasts
(typically run at centers like NCEP* and ECMWF**) to be used as boundary
conditions for the local forecast model.
The observational data (point, station, vertical profile, trajectory,
radar, and satellite) is run through a process atmospheric scientists
call "data assimilation." Assimilation can be thought of as a highly
sophisticated "interpolation" to the grid on which the local forecast
model will be run. It involves solving equations representing the
physics of the situation in addition to the usual geometric and
statistical interpolations. The grids resulting from assimilation are
to be served in such a way that the local model can use them for the
initial conditions. Thus additional datasets have to be served via
standard interfaces
-- gridded datasets resulting from assimilation of observational data
Using the assimilated observational data for initial conditions and the
hemispheric model output for boundary conditions, the local forecast
model runs to produce its own high-resolution gridded output which is
another dataset to be served via standard interfaces.
-- gridded data output from local weather forecast model in region of
airport
There are a few things to note.
1. Local forecasting systems such as the one described above are
already being run on a regular basis, but the OGC and ISO data services
standards are not far enough along to be used in the existing systems.
2. All the datasets in the scenario above can be mapped into the ISO
19123 abstract coverage specification, but it is not clear whether the
WCS is the appropriate protocol specification for serving these
datasets.
3. In addition to mapping such datasets to the ISO abstract model, it is
important to have "application profiles" for encoding these types of
data if they are to be served via standard protocols.
* NCEP is the US National Centers for Environmental Prediction
** ECMWF is the European Center for Medium Range Weather Forecasting
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