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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.


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).


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.


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 ( ). ETOS observation sites provide a regional view to supplement Tennessee's regulatory network ( 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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