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The U.S. Climate Reference Network (USCRN) is a network of climate
stations now being developed as part of a National Oceanic and
Atmospheric Administration (NOAA) initiative. The primary goal
of its implementation is to provide future long-term homogeneous
observations of temperature and precipitation that can be coupled
to past long-term observations for the detection and attribution
of present and future climate change. Data from the USCRN will
be used in operational climate monitoring activities and for placing
current climate anomalies into an historical perspective. The
USCRN will also provide the USA with a reference network that
meets the requirements of the Global Climate Observing System
(GCOS). If fully implemented, the network will consist of about
120 stations nationwide. Implementation of the USCRN is contingent
on the availability of funding.
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The NOAA GEWEX air SURFace eXchange sites (SURFX) sites were
established to provide detailed measurements and information about
the physical and biological processes that occur at the land/surface
interface. Observations from these sites are being used to test
and improve the current generation of land surface models. Key
observations from these sites include the turbulent fluxes of
heat, water vapor, momentum, and carbon dioxide. Mean atmospheric
state variable (ie. radiative fluxe, air temperature, relative
humidity, etc) are also measured. The sites were selected to provide
detailed information for common land use types in the continental
U.S. The sites were initially sponsored by the GCIP (GEWEX Continental
Scale International Project) which has now transitioned to the
GAPP (GEWEX Americas Prediction Project). Both GCIP and GAPP are
part of NOAA's Office of Global Programs. The SURFX sites are
currently serving as reference sites for the Global Hydrology
Program CEOP (Coordinated Enhanced Observations Period). |
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DCNet grew from recognition by dispersion scientists within the
Air Resources Laboratory (ARL) of NOAA that society now faces
a critical question. How do we forecast dispersion in urban areas
and in cities when the meteorological data used by the weather
forecasting community are from locations outside the area of probable
concern? There are no models yet reliable enough to extend the
forecasts of wind direction and speed into the downtown regions
of current concern. Moreover, dispersion computations rely on
assumptions about diffusion rates that are based on experience
in areas that are quite different from cities. After discussion
among scientists from other agencies, it was decided that a Washington
DC testbed should be advocated.
The DCNet stations are more than standard meteorological observing
stations. They report not only the wind speed and direction, but
also the intensity of the turbulence. Sonic anemometry is used.
Sonic anemometers measure the speed of sound along three axes,
and derive from these data the wind speed along these axes with
great accuracy and frequency. A measurement frequency of ten times
per second is typical. The instruments are mounted on 10 m towers,
mostly on the tops of buildings where data on the skimming flow
can be obtained. One of the most visible locations can be seen
from Constitution Avenue, by the Vietnam Memorial. The tower can
be seen on the roof of the National Academy of Sciences (see photo
above), where the Einstein Memorial is located. Other towers are
distributed across the downtown area on the buildings of
the Departments of Energy, Commerce and Agriculture, for example.
The data are analyzed by computers on each tower and are transmitted
to a central analysis location every fifteen minutes.
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The ETOS program is designed as a multi-year effort. ETOS 1999-2002
served as scoping and feasibility studies during which new measurement
techniques, an expanded micro-meteorological monitoring network,
and various vertical atmospheric/chemical sounding systems were
tested. ETOS 2003 developed a regional ozone database to include
both mean hourly averages and hourly histograms of individual
measurement readings. With the 2003 study, ETOS was accepted by
NARSTO (Formerly an acronym for "North American Research
Strategy for Tropospheric Ozone," the term NARSTO has become
simply a wordmark signifying this tri-national, public-private
partnership for dealing with multiple features of tropospheric
pollution, including ozone and suspended particulate matter) for
inclusion in the comprehensive ozone research database. The 2003-2005
study periods were intended to provide a demonstration and evaluation/validation
database for the various operational and development air quality
forecast model components ( http://www.nws.noaa.gov/ost/air_quality/
). ETOS observation sites provide a regional view to supplement
Tennessee's regulatory network (http://www.state.tn.us/environment/apc/ozone/ozonesitemap.php).
The full scope of ETOS 2000+ is continuously under planning and
review, and is refined each year using previous year's analysis
and experience to focus on particular issues within the East Tennessee
region. |
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