WEATHER
AND THE URBAN ENVIRONMENT:
MEETING THE NEEDS OF URBAN COMMUNITIES
October
1, 2004— Although cities themselves represent a very small fraction
of the Earth's surface area, the world's population has become increasingly
urbanized and is now affected by both natural weather and climate patterns,
as well as local-scale (weather and climate) effects derived from the
urbanization process itself. Urban meteorology reveals how weather and
climate interact with all aspects of the urban environment, and provides
insight to help better manage cities and respond to natural and human-induced
hazards.
“With
nearly two-thirds of the U.S. population living in urban areas, there
is a rapidly growing need to understand and predict meteorological conditions
in these areas,” said James
R. Mahoney, Ph.D., assistant secretary of commerce for oceans and
atmosphere and deputy NOAA administrator.
“Special concerns in urban areas include severe weather, air quality,
dispersion characteristics, climate and urban runoff — most of which
impose new demands on forecast models. Several NOAA offices are already
engaged in work and partnerships focusing on this specialized and relatively
new area of meteorology.”
Weather
and the Urban Environment
Not
only are urban areas affected by weather and climate, but they also exert
their own unique influence on local-scale weather and climate. The climate
in and around urban areas is altered in part by the modifications humans
make during urbanization. Naturally vegetated surfaces are replaced by
buildings and paved streets that seal the Earth’s surface and add
vertical dimension to the environment. These changes affect the absorption
of solar radiation/heat storage capabilities, evaporation rates and surface
temperature (often creating what is known as a heat island effect), as
well as local turbulence and wind patterns. This, in turn, can drastically
alter near-surface atmospheric conditions. Human activities in urban areas
also generate water vapor, heat and pollutant emissions that directly
impact the temperature, humidity, air quality and visibility in urban
areas. On slightly larger scales, urbanization can also lead to changes
in precipitation above and downwind of developed areas. Urban life is
also responsible for much of the greenhouse gas emissions that may be
altering climate on regional to global scales. In fact, urbanization alters
just about every aspect of climate and weather in cities.
Challenges
in Urban Meteorology: A Forum for Users and Providers
On
Sept. 21-23, 2004, NOAA's Federal Coordinator for Meteorology, Samuel
P. Williamson, hosted a forum entitled “Challenges
in Urban Meteorology: A Forum for Users and Providers” in collaboration
with the Department of Homeland Security, Science
and Technology Directorate
at the Doubletree Hotel in Rockville, Md. The forum was attended by meteorologists,
emergency managers, scientists and members of the private sector, who
discussed strategies to meet emerging problems and the unique challenges
associated with public health and safety in highly populated urban areas.
(Click on NOAA image below right for a more detailed view of the
tracks of all recorded tornadoes occurring within the immediate Oklahoma
City area from 1890 to 2000.)
Why
address Urban Meteorology Now?
Three factors have come together to make this the optimal time
to address key issues in urban meteorology:
- Advances
in observing systems, weather forecast models and information technologies
provide opportunities to address urban weather needs in ways not feasible
just a decade ago.
- Recent
national and international events have heightened attention to potential
acts of terrorism, particularly in large urban areas. Chemical, biological,
radiological and nuclear releases (whether intentional or accidental)
threaten public health and safety. Atmospheric transport and diffusion
models used to predict the behavior of these harmful substances depends
on inputs from urban environmental observations.
- Health
problems associated with extremes in urban weather and climate can threaten
human health and strain response services. Other urban conditions, such
as air and water pollution can have long-term cumulative effects on
health.
Critical
Urban Meteorology Issues
Many
of the most pressing and serious issues fall within five areas of environmental
concern: severe weather, homeland security, air quality, water quality
and climate change:
- Severe
weather in urbanized areas includes major winter storms, hurricanes,
flash flooding due to locally heavy precipitation, regional flooding
along waterways, periods of extreme high or low temperature and tornadoes.
- Homeland
security issues relate to the dispersion of hazardous materials
by atmospheric and/or waterborne transport. High density urban populations
and the effects of urban topography on the local wind field combine
to make accurate fine-scale prediction of plume movement and concentration
essential, but extremely difficult.
- Air
quality
is affected by atmospheric pollutants resulting from human activities,
including the effects of these pollutants on naturally occurring airborne
substances. Urban traffic and the local, fine-scale effects of the constructed
environment on air movement can exacerbate the impact of air pollutants
on human health. Urban communities are also a major source of air pollution
in downwind rural and natural ecosystems.
-
Water
quality
is affected by the role of the atmosphere and precipitation in the Earth’s
water cycle. Many airborne pollutants are eventually washed out of the
air and can be transported to surface or ground waters and precipitation
events affect the load of contaminants carried into urban water supplies
and/or away from urban communities as storm drainage.
- Climate
issues
for urban communities include the effects of natural variations in climate
cycles (e.g., El Niño) and of anthropogenic influences on climate.
Local and regional variations in seasonal conditions and weather patterns
are critical for long-term urban planning and management.
Crosscutting
Themes
The following crosscutting themes are common to most (if not
all) of the major urban meteorological issues, and therefore should be
taken into account when developing weather and climate products/services
for urban areas:
- Regional
ecosystem planning and management (e.g., urban impacts of wildfires,
waterway and coastal pollution impacts on aquatic/marine systems, regional
air and water quality issues);
- Research
and technology tools, including models to predict weather conditions,
atmospheric transport and dispersion, and climate variations on local
to regional scales;
- Integrated
observation systems to support and validate these models, and provide
data on current conditions;
- Education,
outreach and training for the entire range of current and potential
users of urban environmental data;
- Risk
management and risk communication for time scales ranging from emergency
preparedness (rapid response) and severe weather (intermediate time
scales) to seasonal and generational climate fluctuations (long-term
planning);
- Public
health and safety, including immediate and longer term health effects;
- Information
dissemination and interpretation technologies, systems and interfaces
to move data efficiently from source to appropriate users, in useful
formats;
- Surface
transportation and
- Business
continuity planning.
Meeting
the Challenge
To manage the risks to public safety, health and property, urban decision
makers are demanding more accurate and specific weather and climate information.
In his luncheon address to the forum, Dr. Mahoney stressed that we need
to find a system solution if we are to deliver the improved weather and
climate services required by urban leaders and managers. We must identify
the problems we are trying to solve within the context of the whole urban
system we support and then optimize the solution. Approaching urban meteorology
in a specialized, interdisciplinary manner will provide an integrated
response to the users’ demands for better, more useful information.
Current
Capabilities In Weather and Climate Products And Services
Weather/climate products and services that address urban meteorology
issues are found all across federal agencies, state and local governments,
industries and universities. Some of NOAA’s overarching urban meteorology
capabilities are described below:
- The
NOAA
Weather Service operates weather and climate observation networks
to serve national needs and meet international obligations. It collects
weather and climate data, checks data quality, stores data for access
by other users and assimilates data into numerical and other models
to develop forecasts, advisories and warnings.
- The
NOAA Environmental Satellite, Data and Information Service
manages the U.S. environmental satellite systems used in civil operations.
It also maintains archives of meteorological, oceanographic, geophysical
and solar-terrestrial data.
- NOAA
Research supports meteorological, oceanographic and space missions,
including improving observation and forecast tools for severe weather
and airborne volcanic ash.
- The
NOAA Ocean Service acquires data on water levels, currents,
winds and other parameters to provide information products essential
to marine transportation in coastal areas and ports.
Advances
in urban meteorology will save lives and property, and benefit urban commerce.
NOAA will continue to advance its urban meteorology capabilities and assist
in the coordination of a federal strategy to address the weather-related
needs of urban communities.
Relevant
Web Sites
NOAA
NOAA
National Weather Service
NOAA
Office of the Federal Coordinator for Meteorology
OFFICE
OF THE FEDERAL COORDINATOR FOR METEOROLOGY
HOSTS URBAN METEOROLOGY FORUM (Press
Release, September 2004)
Presentations
from "CHALLENGES IN URBAN METEOROLOGY:
A FORUM FOR USERS AND PROVIDERS"
Media
Contact:
Greg
Romano, NOAA National Weather Service,
(301) 713-0622
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