Model Urbanization Strategy: Summaries, Recommendations and Requirements - Meteorological and Air Quality Models for Urban Areas - page 146

of the fluxes over Basel and Marseilles city centers (Hamdi and Schayes, 2005).
There is a continuing need for modelers and observers to communicate. As mod-
els are used for a variety of purposes, there is a need for increasing the range of
variables observed to ensure as complete a range of evaluation as possible. This
may mean having testbeds and observatories with different objectives and dataset
richness.
There is a wide range of processes and variables that need to be evaluated over a
broad spectrum of conditions (meteorological, morphological, geographical setting,
etc.). For example, a deeper understanding of urban PBL dynamics requires devel-
opment of long-term urban testbeds in a variety of geographic regions (e.g., inland,
coastal, complex terrain) and in many climate regimes, with a variety of urban core
types (e.g., deep versus shallow, homogeneous versus heterogeneous).
The conceptual issue of evaluation of model prediction of the flow within the
canopy is not satisfactorily resolved at this time, and a framework to address this is
needed. Ideal urban testbeds would include quasi-permanent mesoscale networks,
with surface, canyon, rooftop, and PBL meteorological and air quality observations.
These real-time, quality-assured data would be used for real-time urban-scale
weather and air quality forecasts, as well as for emergency response actions after
releases of air toxins (with an indoor-outdoor linkage) and for climate change
impact studies.
In addition, the testbeds should be able to accommodate intensive short-term
field observational studies that could involve turbulent flux and pollutant tracer mea-
surements. Problems also exist in the evaluation of microscale CFD meteorological
model results by use of field study or canyon wind tunnel observations (e.g., wind
tunnel wall effects, the isolated nature of wind tunnel urban domains, the periodic
LES and CFD lateral boundary conditions). When comparisons are done with these
limitations in mind (e.g., only compare model results with wind tunnel results over
urban centers), however, they show good agreement among the methods.
Obviously, with increasing evaluation, there will be enhanced development of the
models. It is also clear that, within the chain of needs between meteorological forc-
ing and applications, there is a range of new developments needed (see Sect. 15.3).
Finally, user friendly and multifaceted urban databases and enabling technology
are critical and core capabilities for advancing urban modeling and boundary layer
research. We see the National Urban Database and Access Portal Tool as a research
and development resource toward future improved UCP descriptions and scientific
bases for advanced urban modeling applications. With careful thought to its imple-
mentation, the concept of this prototype system is extensible on an international
basis. For such an enterprise, we suggest several guiding principles be adopted.
First, that this type of database be open and community-wide and available both
universally and in as an unrestricted form as possible. Second, that both protocols
and mechanisms should be established for its maintenance, upgrading, updating,
and archiving. Further, issues of availability and sources of high-resolution data sets
will need to be addressed.
Disclaimer: The research presented here by one of its authors (Ching) was per-
formed under the Memorandum of Understanding between U.S. EPA and the U.S.