Geography Reference
In-Depth Information
solar activity and other human activities. Secondly, some uncertainties may hide
behind the data processing, parameterization, and WRF model itself. Therefore,
there is still further work to do in order to get more accurate assessment.
7.5 Impacts of Future Urban Expansion on Regional
Climate in the Northeast Megalopolis, USA
Urban expansion is regarded as one of the most noticeable effects of human
activities that cover a very small fraction of Earth's land surface, but notably
affects climate. It usually removes and replaces crops and natural vegetation with
non-evaporating and non-transpiring surfaces, such as metal, asphalt, and concrete
(Basara et al.
2010
).These artificial surfaces are characterized by specific thermal
properties (albedo, thermal conductivity, and emissivity), which are different from
those of nonurban areas (Weng et al.
2004
).The alteration of regional thermal
properties along with urban expansion will inevitably result in the redistribution of
incoming solar radiation and affect the surface energy budgets (Zhang et al.
2009
).
Consequently, the wind velocity, mixing layer depth, and thermal structures in the
boundary layer, as well as the local and regional atmospheric circulations are
changed (Lei et al.
2008
).
The primary objective of this study is to determine the influences of future
urban expansion on regional climate at different temporal scales in developed
megalopolis. The major contribution of this case study is that it will provide
evidences for influences of future urban expansion on regional climate at the scale
of megalopolis and helps to understand the integrated effects of combination and
interaction of multiple cities and their surroundings.
7.5.1 Data and Methodology
7.5.1.1 Study Area
The Northeast megalopolis is the most populous and largely developed mega-
lopolis of USA. It is constituted by a number of cities including Baltimore, Boston,
Harrisburg, Newark, New York City, Philadelphia, Portland, Providence, Rich-
mond, Springfield, Hartford, and Washington (Gottmann
1964
). The megalopolis's
population is expected to reach sixty million by 2025. This megalopolis is chosen
as case study area because it is one of the most typical megalopolis globally, which
can be regarded as the example of future megalopolis development.
