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The GEWEX
(Global Energy and Water Cycle Experiment) Continental-Scale International Project (GCIP) was established "to improve scientific
understanding and to model on a continental scale the coupling between the atmosphere and
the land surface for climate prediction purposes." Improved models for hydrologic and
energy fluxes over regional land surfaces will need to be scaled and coupled to new
high-resolution global climate models to achieve these GCIP goals. Such coupled models are
essential for understanding and predicting the potential regional impacts of shorter-term
climate anomalies and longer-term climate change. The GCIP research effort is designed to
ascertain the impacts of such climate variability by focusing on "fast climate"
processes (such as clouds, precipitation and surface water behavior) which are important
to models that simulate the connection between water and energy fluxes over different
spatial and temporal scales.
While the GCIP activities concentrate on the entire
Mississippi River basin, this geographical region has been divided into four large-scale
areas (LSA). A phased research timetable emphasizes each LSA for a duration of about two
years during the GCIP Enhanced Observational Period (EOP) under way from 1996 through
about 2000. The LSA of interest to the Upper Missouri River Basin (UMRB) Pilot Project is
the "Large Scale Area-Northwest (LSA-NW)" because of its approximate
geographical congruency with the UMRB. In this region the behavior of groundwater in
aquifers is also important to the water budget and water resources.
The UMRB Pilot Project (UMRBPP) research is intended
to implement some of the studies that will be needed to support the GCIP EOP in the
LSA-NW. The modeling and observational tasks focus on the Black Hills region of South
Dakota and Wyoming, a candidate Intermediate Scale Area (ISA) for GCIP, but are related to
archetypal sub-regions that are representative of similar regions in the LSA-NW and in
other parts of the world. Therefore, the information obtained from these investigations of
this UMRB sub-region will be transferable to similar watersheds and land surfaces
elsewhere. The UMRBPP research plan relates directly to three of the GCIP science
objectives:
- Determine and explain the annual, interannual and
spatial variability of the water and energy cycles within the Mississippi River basin.
- Develop and evaluate coupled
hydrologic/atmospheric models at resolutions appropriate to large-scale continental
basins.
- Provide access to comprehensive in-situ, remote
sensing and model output data sets for use in GCIP research and as a benchmark for future
studies.
We are coordinating closely with other GCIP, and
especially GCIP LSA-NW, activities. This coordination is facilitated by the October 14-16,
1998, LSA-NW Detailed Design workshop hosted at EROS Data Center (EDC) in Sioux Falls, SD.
The GCIP multi-scale approach considers ISAs and
Small Scale Areas (SSA) nested within the LSA, with eventual aggregation from the smaller
scales into a continental-scale synthesis. In view of the resolution of present day
operational Numerical Weather Prediction (NWP) and General Circulation Models (GCM), and
available Regional Mesoscale Models (RMM), some capability must also be developed to
disaggregate the model products to yield information at the smaller scales that are of
interest for most practical applications. The aggregation and disaggregation techniques
involve inherently nonlinear scale interactions, and must deal with the various
heterogeneities of topography and other factors over the land surface. Intensive research
is needed to develop the required knowledge and techniques and make them viable, and the
UMRBPP is intended to contribute toward that end.
The details of the UMRBPP research plan are covered
under Modeling and Observational Tasks. The overall UMRBPP research strategy can be
summarized as follows:
- Conduct a one year simulation with surface and
subsurface components of the coupled model to study groundwater effects.
- Determine model sensitivity to the scaling of
orography and other observational variables.
- Conduct the IOP to provide high resolution data to
assess measurement uncertainties.
- Challenge components of the coupled model, which
includes atmospheric, land-surface processes, and surface and subsurface hydrologic
components, with selected case studies from the IOP.
- Examine implications of results with respect to
GCIP LSA studies.
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