NOAA CLIMATE REFERENCE NETWORK CALIBRATES THE FUTURE

August 2, 2004 — A new network of premier environmental climate-monitoring stations has now begun operating in the United States. The U.S. Climate Reference Network is a network of climate instruments designed to answer the question, "How has the climate of the United States changed?" — 50 years from now. The USCRN will provide the most accurate and reliable environmental climate data that the United States has ever collected and disseminated. The primary goal of the USCRN is to provide future long-term homogeneous observations of temperature and precipitation. Coupling these with long-term historical observations will support the detection and attribution of present and future climate change. Thus, data from the USCRN will be used in operational climate monitoring activities and for placing current climate anomalies into an historical perspective. Stations are presently operating in 35 States, with the goal of more than 100 sites nationwide (Click on NOAA image below right for a larger view of map showing USCRN sites across the United States).

The USCRN will also provide the United States with a climate and environmental monitoring network that meets national needs, and international commitments to monitor and document climate change. "The Climate Reference Network will help fill an important land based gap in U.S. data that will be needed in a larger and more comprehensive Earth observation system being developed by more than 49 countries," said retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. “With important components like the USCRN, the Earth observation system will help address emerging global issues and lay the groundwork for improved environmental decision-making, economic growth and prosperity.”
Furthermore, with more than $3 trillion of U.S. GDP affected by climate and weather (including the agriculture, energy, construction, travel and transportation industry sectors) there are powerful economic, as well as environmental incentives for gaining a greater understanding of these phenomena. The nation has already made significant investments in space and surface-based observing systems, including its ability to monitor the ozone layer using spacecraft and aircraft and the TAO/Triton Array of ocean buoys that helped forecast the most recent El Niño six months in advance. The USCRN builds upon these observing systems and will be integrated into a new more comprehensive weather and climate surface observing network to provide the nation with new, more accurate data points in a swift and affordable manner.

USCRN site selection is particularly important since the local environment around these sites must remain largely stable for 50 years or more and be representative of conditions and regions throughout the nation. USCRN stations must also be located in fairly pristine environments to help eliminate local human influences (i.e., development, pollution, urban heat island effect, etc.) from confounding the interpretation of any observed changes in climate. Thus, NOAA’s Regional Climate Centers ensure that selected sites meet stringent criteria; such as clearance from obstructions, clear terrain, good exposure for instruments and separation from micro-climate inducing influences ranging from small ponds to urbanization.
Most USCRN stations are located in State and National parks, national wildlife refugees, government installations or on university campuses. A typical ground station consists of a slatted wind fence surrounding a precipitation gauge, plus a 10-foot tower supporting a satellite communications antenna, a solar panel and battery and a series of sensors (Click on NOAA image below right for a larger view of the proposed typical USCRN station configuration).

Some USCRN sites are located near existing meteorological observation sites, such as the U.S. Historical Climate Network and the U.S. Cooperative Observer network. After a few years of operation, data from a USCRN station can be used to calibrate the data from these other networks, through transfer functions, thus creating a longer homogeneous time series of observations.

The USCRN systems were designed to be highly reliable, expandable and maintainable. A suite of instruments automatically collects and transmits hourly climate observations from each station via the GOES Satellite to the NOAA National Climate Data Center in Ashville, N.C. Currently data from the installed stations comprising the UNCRN are being ingested at the NCDC at a rate of 99.7 percent of all possible measurements. The climate data is subsequently posted on the NCDC Web site in near-real time. NCDC also conducts operational quality control monitoring, archiving and user access functions.

The USCRN instruments operate under varied and sometimes extreme weather conditions, without the need for constant human intervention. Engineers at the NOAA Air Resources Laboratory’s Atmospheric Turbulence and Diffusion Division at Oak Ridge, Tenn., are developing and installing the instrument suites. They also maintain the network, working in partnership with host agencies at the sites. Instruments are tested before deployment and are calibrated to National Institute of Standards and Technology standards.

The NOAA Office of Systems Development, working in concert with the NCDC, leads the USCRN acquisition and implementation.

Why should there be a Climate Reference Network?
Analyzing the climate record entails some uncertainty invoked by a history of changes in instrumentation, time of observation, standard exposures of instruments and quality of equipment maintenance. The 1997 Conference on the World Climate Research Program concluded that the global capacity to observe the Earth’s climate system is inadequate and is deteriorating worldwide. Without action to reverse this decline and develop the Global Climate Observation System, the ability to characterize climate change and variations over the next 25 years will be even less than during the past quarter century.

The USCRN Program helps reverse this decline in data quality for climate purposes. Each USCRN site carefully records the primary measurements of climate — air temperature and precipitation — supplemented with other measurements (e.g., wind speed, solar radiation, surface temperature (infrared), relative humidity and wetness and several engineering variables which monitor the operating conditions of the equipment) and redundancy of critical sensors (i.e., backup instruments) to ensure the most accurate climate change monitoring. For example, instead of using just one thermometer, each USCRN station uses three temperature sensing instruments. Each thermometer has three concentric shields that eliminate biasing effects due to solar radiation. A fan blows air through the shields, past the temperature sensors, ensuring that they measure the true ambient air temperature. Triple measurements ensure that potential errors can be detected immediately. USCRN precipitation measurements also use advanced technology. Instead of conventionally measuring the volume of precipitation collected in the universal precipitation gauge, USCRN precipitation measurements are calculated digitally based on the mass weight of the liquid collected in the rain gauge. Windshields (fences) built around the gauge enable USCRN researchers to measure even the smallest amounts of precipitation (i.e., light snow on a windy day). Additionally, a tipping bucket rain gauge provides another independent measurement of precipitation. With three independent temperature measurements and four measurements for precipitation, the USCRN provides the most accurate temperature and precipitation measurements to date.

The goal of the USCRN is to ensure that future changes and variations in primary measurements at specific sites can be monitored without the need for uncertain adjustments and corrections to the data. The network, when fully deployed, will provide adequate spatial coverage to monitor the national-scale, decadal-to-centennial temperature and precipitation trends across the United States. In doing so, the USCRN will provide the nation with a long-term (50 to 100 years) and first-class observing network that will serve as the nation's benchmark climate reference network. The USCRN Program will also serve as a model for establishing similar benchmark networks in other countries participating in the Global Climate Observing System.

The new USCRN will enable NOAA to better serve the needs of its customers in industry, the general public and the government for increasingly more accurate data, information and knowledge regarding potential changes in climate. The USCRN will add confidence to existing NOAA assessments of climate trends and variations that are so critical to the development of long-term adaptation strategies to minimize climate risks and maximize new climate opportunities.

Relevant Web Sites
U.S. Climate Reference Network

NOAA National Climate Data Center

NOAA National Environmental Satellite Data and Information Service

NEW CLIMATE MONITORING NETWORK NOW OPERATIONAL

NOAA TO COMMISSION NEW CLIMATE MONITORING NETWORK

Media Contact:
John Leslie, NOAA Satellites and Information Service, (301) 457-5005