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1
Test Bed Leaders
- Vincent
Fortin,
Meteorological Service of Canada,
Canada
- Alain
Pietroniro, National Water Research Institute, Canada
2
Test Bed Description
The
Great Lakes basin, located at the Canada-US
Border (Fig. 1), contains approximately 20% of the world fresh
water
supply. The watershed area is approximately 1 million km² and
close to 40
million people live on this watershed, including roughly one third of
the
population of Canada.
Water empties from the Great Lakes into the St. Lawrence River and
passes
through the Moses-Saunders dam at the outlet of Lake Ontario.
Decisions
on Lake Ontario outflows are
typically
taken
on a weekly basis and are based on lake levels, forecasted inflows to
the lake
and forecasted outflows from the Ottawa River basin for the
following
weeks,
and thus may benefit from better ensemble streamflow forecasts both of Lake Ontario
inflows and Ottawa
River flow for the
first 15
days. At this time scale, ensemble streamflow forecasts should benefit
from an
accurate analysis of initial conditions (snow and soil moisture) as
well as
ensemble weather forecasts.
Fig.1 The Great Lakes basin (1)
3
Key Scientific Questions
While
the Great Lakes basin is fairly
large, individual lakes and in particular Lake
Ontario,
are fed by a number of much smaller watersheds. It is known that for
some of
these watersheds, for example the Raquette river which takes its source
in the Adirondack
mountains, basin
average snow water equivalent
is better estimated from a high resolution analysis.
(2) It is also
known that the Great Lakes influence both winter-time and summer-time
weather
at the regional scale. (3,4) Given the
importance of resolving the terrain and the lakes for realistic
hydrometeorological modelling of the Great Lakes, this test bed can be
used to
test the influence of increased resolution both for the land-surface
scheme and
for the atmospheric model on the accuracy and reliability of ensemble
streamflow forecasts and ensemble weather forecasts.
4
Key
Objectives of the Research Project
- To
demonstrate the importance of
relatively
detailed atmospheric and hydrologic modeling for medium-range
atmospheric and
hydrologic forecasting on large basins.
- To
evaluate
the added value of using the new North American
Ensemble
Forecasting System (NAEFS), compared to only using ensemble forecasts
from the
individual centers (CMC and NCEP), but also compared to the GFS
reforecasts.
- There
is
considerable hydroelectric power production on the basin,
and as
some of the hydropower companies such as Hydro-Québec can
readily use better
ensemble streamflow forecasts to improve their operations, the testbed
can be
used to evaluate the added economic value of using ensemble weather
predictions
instead of climatology for lead times of up to two weeks. The HEPEX
scientific
community will be asked to propose and test different strategies for
downscaling the atmospheric forecasts for specific events, and for
hydrological
modelling. The user community will be asked to help evaluate the
economic value
of the forecasts.
5
Data Resources
The
Great
Lakes
Environmental Research
Laboratory
(5) maintains a
comprehensive database of hydrologic, meteorologic, climatic,
nivometric and
physiographic data:
- Monthly
hydroclimatic time series dating back more
than a
century.
- More
than
180 hydrometric stations on
unregulated basins on the Canadian side of the border.
- Daily
hydrometric and
meteorologic observations are available freely through the web,
6-hourly data
is available for synoptic weather stations.
- A
15-km
analysis of
precipitation
combining the regional GEM model first guess with synoptic observations
is
available in realtime for the whole basin, as well as a 10-km radar
mosaic.
Land cover information
is available for
the US through the
Great
Lakes Assessment Project of the U.S.
forest service (6)
or through the NOAA Coastal Services
Center
(7), and for Canada
through the Ontario
land cover database. Soil
information is available from the STATSGO (8) and CANSIS (9) databases.
The U.S. and Canada
are presently putting in place a
comprehensive GIS database for the Great Lakes.
(10)
Elevation and land
cover at a 1 km
resolution and information on soil type at a 10 km resolution is
however
readily available from the Canadian Meteorological Centre and could be
provided
in GRIB format. 90m elevation data is also available freely (30m
elevation data
is available over the United States), but needs
to be processed to obtain
a complete, higher-resolution digital elevation model over the whole
basin.
Using elevation from the SRTM mission (available freely at a 90m
resolution) is
also a possibility over Canada.
6
Recent activities
Great Lakes Testbed Update 2006.
(1) Taken from the web site
of the
Council of Great Lakes Governors,
http://www.cglg.org/projects/water/docs/6-30-05/GLBasinMap.pdf
(2)Lefaivre,
D.; Pellerin, P.; Ritchie, H.; Turcotte, R.; Fortin, V.;
Pietroniro,
A.; and Lamontagne, M. 2004. Water level forecasting in the St.
Lawrence River
between Lake St. Louis and Quebec
City:
Ongoing operation and future outlook. 11th Annual International
Conference on
the St. Lawrence River Ecosystem, Cornwall,
Ontario.
May 18-19th, 2004.
(3)
Bosart,
L. and T.J. Galarneau Jr. 2005. The Influence of the Great Lakes on
warm season
weather systems during BAMEX, 6th AMS Coastal Meteorology Conference, San Diego
CA,
January 10-13th, 2005.
(4)
http://www.islandnet.com/~see/weather/elements/lkefsnw3.htm
(5)
http://www.glerl.noaa.gov
(6)
http://www.umesc.usgs.gov/umesc_spatial/projects/gr_lakes_assessment/usfs_page.html
(7) http://www.csc.noaa.gov/crs/lca/greatlakes.html
(8)
http://www.ncgc.nrcs.usda.gov/products/datasets/statsgo/ (9)
http://sis.agr.gc.ca/cansis/
(10)
http://www.glfc.org/glgis/
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