USHCN Stations Were Selected on the Basis of Several Factors, but Siting Conditions Played a Limited Role

According to NCDC officials, achieving a relatively uniform geographic  distribution across the contiguous 48 states was a high priority when  selecting USHCN stations and was balanced with other factors, including  how long stations had collected temperature records, limited periods of  missing temperature data, and the stability of measurement conditions. NCDC officials told us they considered other  factors, such as geographic distribution and a long history of temperature  records, to be more important to their ability to analyze long-term  temperature trends than strict adherence to NWS’s siting standards. With regard to management requirements for USHCN  stations, we found that the weather forecast offices generally but not  always met requirements to conduct annual inspections and update  station records. Close to Half of USHCN Stations Do Not Meet NWS Siting Standards

The survey responses we received from weather forecast offices that  manage stations included in the USHCN indicate that about 42 percent of  the active stations in 2010 did not adhere to one or more of the NWS  siting standards for air temperature measurement. The use of  temperature-measuring equipment that is connected by a cable to an  indoor readout device can require installing equipment closer to  buildings than specified in the standards, according to our survey. According to NCDC and  NWS officials, it is important to annually visit stations and keep station  records up to date so that users of the stations’ temperature records,  such as NCDC, know the conditions under which the observations were  recorded. NWS Does Not Centrally Track Whether USHCN Stations Meet Siting Standards or Have a Policy for Addressing Stations That Do Not Meet the Standards

NWS does not use its information systems to centrally track whether  USHCN stations adhere to siting standards or if weather forecast offices  are meeting the requirement to update station records at least once every  5 years. NWS Does Not Have an Agencywide Policy to Address Stations That Do Not Adhere to Siting Standards

NWS does not have an agencywide policy for stations not adhering to  siting standards that clarifies for staff in weather forecast offices whether  the stations should be closed, relocated, or maintained in their present  condition to preserve the continuity of their temperature records. Standards for internal control in the federal government call for federal  agencies to document their policies and procedures to help managers  achieve desired results. As a result, the  agency cannot easily measure the USHCN’s performance against its  siting standards and management requirements. In the absence of such policy, it is not  clear to weather forecast office officials whether stations that do not  adhere to siting standards should remain open because data continuity is  important for analyzing long-term climate trends, or whether the stations  should be moved or closed. Recommendations for Executive Action

To improve NWS’s ability to manage the USHCN in accordance with  performance management guidelines and federal internal control  standards, as well as to strengthen congressional and public confidence  in the data the network provides, we recommend that the Acting Secretary  of Commerce direct the Administrator of NOAA to take the following two  actions:    Enhance NWS’s information system to centrally capture information  that would be useful in managing stations in the USHCN, including  (1) more complete data on siting conditions (including when siting  conditions change), which would allow the agency to assess the  extent to which the stations meet its siting standards, and (2) existing  data on when station records were last updated to monitor whether  the records are being updated at least once every 5 years as NWS  requires. Appendix I: Scope and Methodology

To determine how the National Oceanic and Atmospheric Administration  (NOAA) selected stations for the U.S. To examine in greater depth the extent to which USHCN stations meet  siting standards and management requirements for weather-monitoring  stations, we visited a nonprobability sample of 8 NWS weather forecast  offices. To evaluate the extent to which NWS tracks USHCN stations’ adherence  to siting standards and management requirements and has established a  policy for addressing stations that do not adhere to siting standards, we  took several actions. The  differences reflect the fact that, whereas NCDC designated stations for  the USHCN from an existing network of NWS weather-monitoring  stations, NOAA has specifically located and designed stations in the  newer networks for monitoring the nation’s climate.
Why GAO Did This Study

The National Oceanic and Atmospheric Administration (NOAA) maintains a network of weather-monitoring stations known as the U.S. Historical Climatology Network (USHCN), which monitors the nation's climate and analyzes long-term surface temperature trends. Recent reports have shown that some stations in the USHCN are not sited in accordance with NOAA's standards, which state that temperature instruments should be located away from extensive paved surfaces or obstructions such as buildings and trees. GAO was asked to examine (1) how NOAA chose stations for the USHCN, (2) the extent to which these stations meet siting standards and other requirements, and (3) the extent to which NOAA tracks USHCN stations' adherence to siting standards and other requirements and has established a policy for addressing nonadherence to siting standards. GAO reviewed data and documents, interviewed key NOAA officials, surveyed the 116 NOAA weather forecast offices responsible for managing stations in the USHCN, and visited 8 forecast offices.

What GAO Found

In choosing USHCN stations from a larger set of existing weather-monitoring stations, NOAA placed a high priority on achieving a relatively uniform geographic distribution of stations across the contiguous 48 states. NOAA balanced geographic distribution with other factors, including a desire for a long history of temperature records, limited periods of missing data, and stability of a station's location and other measurement conditions, since changes in such conditions can cause temperature shifts unrelated to climate trends. NOAA had to make certain exceptions, such as including many stations that had incomplete temperature records. In general, the extent to which the stations met NOAA's siting standards played a limited role in the designation process, in part because NOAA officials considered other factors, such as geographic distribution and a long history of records, to be more important. USHCN stations meet NOAA's siting standards and management requirements to varying degrees. According to GAO's survey of weather forecast offices, about 42 percent of the active stations in 2010 did not meet one or more of the siting standards. With regard to management requirements, GAO found that the weather forecast offices had generally but not always met the requirements to conduct annual station inspections and to update station records. NOAA officials told GAO that it is important to annually visit stations and keep records up to date, including siting conditions, so that NOAA and other users of the data know the conditions under which they were recorded. NOAA officials identified a variety of challenges that contribute to some stations not adhering to siting standards and management requirements, including the use of temperature-measuring equipment that is connected by a cable to an indoor readout device--which can require installing equipment closer to buildings than specified in the siting standards. NOAA does not centrally track whether USHCN stations adhere to siting standards and the requirement to update station records, and it does not have an agencywide policy regarding stations that do not meet its siting standards. Performance management guidelines call for using performance information to assess program results. NOAA's information systems, however, are not designed to centrally track whether stations in the USHCN meet its siting standards or the requirement to update station records. Without centrally available information, NOAA cannot easily measure the performance of the USHCN in meeting siting standards and management requirements. Furthermore, federal internal control standards call for agencies to document their policies and procedures to help managers achieve desired results. NOAA has not developed an agencywide policy, however, that clarifies for agency staff whether stations that do not adhere to siting standards should remain open because the continuity of the data is important, or should be moved or closed. As a result, weather forecast offices do not have a basis for making consistent decisions to address stations that do not meet the siting standards.

What GAO Recommends

GAO recommends that NOAA enhance its information systems to centrally capture information useful in managing the USHCN and develop a policy on how to address stations that do not meet its siting standards. NOAA agreed with GAO's recommendations.