Climate Monitoring: NOAA Can Improve Management of the U.S. Historical Climatology Network
Published: 2011-08-31T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: 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.
section_title: What GAO Found
paragraphs: 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.
section_title: What GAO Recommends
paragraphs: 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.

section_title: Letter
paragraphs: The National Oceanic and Atmospheric Administration’s (NOAA) weather  forecast offices maintain a network of thousands of weather-monitoring  stations throughout the United States, some with temperature records  stretching back well over a century. These weather-monitoring stations  are equipped to measure meteorological conditions at ground level— usually the daily maximum and minimum temperatures and 24-hour  precipitation totals—to support weather forecasts and for the study of  climate. In 1987 NOAA designated a subset of these weather-monitoring  stations as the U.S. Historical Climatology Network (USHCN). The  purpose of the USHCN is to monitor the nation’s climate and, in  particular, to analyze long-term surface temperature trends. On the basis  of their analysis of data from a variety of sources, including temperature  records from the USHCN, NOAA scientists have concluded that the  average surface temperatures across the nation have warmed over the  past century.
The temperature measurements used in NOAA’s analysis have been  taken largely by trained volunteer observers at the weather-monitoring  stations that are part of the USHCN. The stations are located at private  residences, farms, and parks, as well as on the properties of universities,  water treatment plants, airports, and other institutions. The volunteer  observers generally record temperature measurements on a daily basis  using equipment that NOAA has placed on their properties. NOAA has  established standards for air temperature measurement, which state,  among other things, that temperature instruments should be located away  from extensive paved surfaces or obstructions such as buildings and  trees. Siting conditions at stations can change over time, however,  particularly for stations with many years of data, as volunteer observers  make changes to their properties, urbanization occurs, or local land uses  change. Recent reports have shown that some USHCN stations are not  sited in accordance with NOAA’s standards.
According to NOAA officials, for many years the agency has recognized  the need to improve confidence in its data on changes to the national  climate and, as part of this effort, in 2001 took the initiative to establish a  new national climate observation network, the U.S. Climate Reference  Network. NOAA is also developing another new observation network  designed to monitor regional climate trends. Unlike many of the stations  in the USHCN, the monitoring stations for these new networks are  generally located on government rather than private property and do not  require a human observer to record temperature measurements.  According to NOAA officials, however, the agency plans to continue  relying on data from the USHCN to help characterize national and  regional temperature trends.
You asked us to examine issues related to the siting of USHCN stations.  Specifically, we examined (1) how NOAA selected weather-monitoring  stations for inclusion in the USHCN, (2) the extent to which such stations  meet siting standards and management requirements for weather- monitoring stations, and (3) the extent to which NOAA 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. As we discussed with your office, we focused our  examination of these issues on NOAA’s management of the USHCN and  did not assess the effect of stations not meeting siting standards on the  reliability of NOAA’s analysis of temperature trends.
To examine NOAA’s selection of USHCN stations, we reviewed NOAA  documents describing the selection process, interviewed NOAA  scientists, and analyzed NOAA data on all stations that constitute the  USHCN. We analyzed the data to determine the extent to which USHCN  stations meet the criteria NOAA scientists considered important for the  purpose of monitoring long-term temperature trends, such as geographic  distribution of stations. To assess the extent to which USHCN stations  meet siting standards and management requirements for weather- monitoring stations, we surveyed all 116 NOAA weather forecast offices  in the contiguous 48 states, which are responsible for managing these  stations, and received a response rate of 100 percent. Our questionnaire  included questions regarding adherence to siting standards, reasons for  stations not adhering to the standards, and general management  challenges. We visited a nonprobability sample of 8 weather forecast  offices across the country to discuss these issues in greater depth,  observe siting conditions at a total of 19 USHCN stations managed by the  offices, and review weather forecast office files for network stations to  examine adherence to general management requirements for weather- monitoring stations. The set of 19 USHCN stations we visited was also a  nonprobability sample we selected to ensure that we observed a variety  of siting conditions. To ensure geographic distribution in the weather  forecast offices we visited, we selected 2 offices in each of the four NOAA  regions in the contiguous United States, and we selected the specific  offices we visited to ensure a range of sizes in terms of the offices’  forecast areas. Because we used a nonprobability sample of weather  forecast offices and USHCN stations to visit, the information we obtained  from these visits cannot be generalized to other weather forecast offices  or USHCN stations. The visits instead provided us with more in-depth  information on the perspectives of various participants in the weather  forecast offices about managing weather-monitoring stations and  examples of station siting conditions. To evaluate the extent to which  NOAA 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 reviewed NOAA  documents and interviewed NOAA officials responsible for managing  weather-monitoring stations. Appendix I presents a more detailed  description of our scope and methodology.
We conducted this performance audit from August 2010 through August  2011, in accordance with generally accepted government auditing  standards. Those standards require that we plan and perform the audit to  obtain sufficient, appropriate evidence to provide a reasonable basis for  our findings and conclusions based on our audit objectives. We believe  that the evidence obtained provides a reasonable basis for our findings  and conclusions based on our audit objectives.
subsections: section_title: Background
paragraphs: NOAA’s National Weather Service (NWS) manages the approximately  11,000 weather-monitoring stations across the country that are part of the  Cooperative Observer Program. Volunteer observers at the stations  generally record daily maximum and minimum temperatures and 24-hour  precipitation totals and submit the data to NWS over the telephone, by  Internet, or by mail. The records for stations in the Cooperative Observer  Program can stretch back well over a century, with some records  predating the establishment of NWS in 1890. NWS uses data from these  Cooperative Observer Program stations to support weather forecasts and  warnings and other public service programs. The data are also used by  others, including state climatologists, farmers, and resource planners  such as energy providers that use weather information to anticipate and  plan for varying levels of energy consumption.
NOAA’s National Climatic Data Center (NCDC) established the USHCN  in 1987 by selecting a subset of weather-monitoring stations from the  existing Cooperative Observer Program network of stations. The USHCN  currently consists of 1,218 stations. NCDC has twice revised the makeup  of stations that compose the USHCN—in 1996 and 2009—primarily to  extend the weather records of stations that have closed over time as  volunteer observers have discontinued their service. To address this  issue, NCDC added data from nearby stations with similar temperature  trends that are continuing to gather and report data. In all, NCDC has  added over 100 stations as of the latest revision in 2009. NCDC does not  have a direct role in managing USHCN stations but relies on NWS’s  weather forecast offices throughout the contiguous United States to  continue to manage the stations as part of the larger group of weather- monitoring stations in the Cooperative Observer Program. For example,  NCDC relies on weather forecast offices to maintain records on the  location of the stations and other conditions that can affect weather  observations, including the types of equipment used to measure  temperature and precipitation and the time of observation.
NCDC uses USHCN data to assess and monitor climate variation and  change, including to quantify national- and regional-scale temperature  trends within the contiguous 48 states. On the basis of its analysis of  USHCN data, NCDC estimates that the average surface temperature  across the contiguous states has warmed by about 1.4 degrees  Fahrenheit since 1895. NCDC’s analysis has also identified areas of the  country where temperatures have cooled or remained relatively stable.  NCDC combines temperature records from the USHCN with temperature  records from weather-monitoring stations around the world to analyze  global temperature trends. This analysis has in turn been summarized in  the assessment reports of the Intergovernmental Panel on Climate  Change, an international body that reviews and assesses the most recent  scientific and technical information produced worldwide relevant to the  understanding of climate change.
NWS headquarters establishes the policies, standards, and requirements  for managing the Cooperative Observer Program, and weather forecast  offices in six NWS regions (central, eastern, southern, western, Alaska,  and Pacific) have responsibility for recruiting and training observers and  installing and maintaining temperature-measuring equipment and rain  gauges on observers’ properties. NWS applies the same standards and  requirements to all stations in its Cooperative Observer Program,  including those in the USHCN. In particular, NWS has established siting  standards for measuring air temperature to ensure uniformity in meeting  national and international requirements for climate observation. The  standards, which cover conditions in the immediate vicinity of the stations,  specify that temperature-measuring instruments should    not be sited on rooftops;    be installed over level terrain;    be installed at least 100 feet from any extensive concrete or paved  surface;    be mounted 4 to 6 feet above the surface; and    be no closer than four times the height of any nearby building, tree,  fence, or similar obstruction.
NWS guidelines state that implementation of these standards should be  flexible and balanced with other factors, such as the availability of space.  According to NWS, these siting standards are based in part on  recommendations of the World Meteorological Organization, an agency of  the United Nations that, among other things, coordinates the activities of  member states to generate data and information on weather and climate in  accordance with international standards. For example, according to World  Meteorological Organization guidelines, the best sites for measuring air  temperature are over level ground; freely exposed to sunshine and wind;  and not shielded by or close to trees, buildings, and other obstructions.
NWS has also established management requirements for weather- monitoring stations that call for inspections of stations and updates of  station records to reflect any changes. The requirements for inspections  call for a minimum of one inspection by weather forecast office officials per  year and specify that during these inspections, the officials are to review  observers’ practices for taking weather measurements, check equipment  and perform any needed repairs, and assess the conditions surrounding  the station, among other things. The management requirements state that,  even if there are no changes at a station, officials from weather forecast  offices should update each station record at least once every 5 years. To  provide a complete and permanent record of a station, NWS has designed  an information system that weather forecast offices are to use to record the  dates of inspections and update station records. Such records are used by  NCDC and other researchers to help interpret weather records from a  station and determine how factors such as station location and  measurement instruments affect the weather records. Figure 1 depicts the  roles of NWS and NCDC in managing the USHCN.
section_title: USHCN Stations Were Selected on the Basis of Several Factors, but Siting Conditions Played a Limited Role
paragraphs: 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.  According to NCDC officials, consideration of siting conditions in the  immediate vicinity of stations played a limited role in both the initial  selections in 1987 and when stations were added in 1996 and 2009  because they considered other factors, such as geographic distribution, to  be more important to the analysis of long-term temperature trends.
subsections: section_title: NCDC Selected USHCN Stations by Balancing Geographic Distribution with Other Factors
paragraphs: NCDC officials told us that in selecting stations for the USHCN, the  agency placed a high priority on achieving geographic distribution across  the contiguous 48 states, so that the network could help identify both  national and regional warming and cooling trends. To achieve the  geographic distribution needed to identify regional trends, according to  agency officials, NCDC aimed to select a minimum of two stations from  each of the 344 climate divisions across the country. NCDC officials  acknowledged that they encountered difficulties achieving the desired  geographic distribution in certain areas of western states—such as  Nevada—that have a relatively low population density and thus fewer  stations to choose from because of a lack of volunteers to serve as  observers. As a result, according to NCDC officials, station density is  slightly higher across the eastern states than in the western states. Our  analysis of all 1,218 USHCN stations (including active stations and those  that were inactive or closed) found that while NCDC generally met its aim  of two stations per climate division, 14 percent of climate divisions had  fewer than two stations. As of April 2011, 20 percent of climate divisions  had fewer than two active stations (see fig. 2). According to NCDC  officials, the existing climate divisions are only one way to partition the  nation’s climate, and if divisions were being developed today, the climate  divisions would differ in number and in the areas they cover.
According to NCDC officials and documents describing the process used  to select USHCN stations in 1987 and to amend the list of stations in  1996 and 2009, the agency also sought stations that had temperature  records dating back to the early 20th century, had limited periods of  missing data, and had a limited number of station changes, but  sometimes made exceptions to these factors.    Number of years of temperature records. In order to detect long-term  temperature trends, NCDC aimed to select stations that had a long  history of temperature records, ideally dating back to the early 20th  century. In some cases, however, NCDC selected stations with a  shorter history of temperature records than was ideal to ensure  geographic distribution of stations across the contiguous 48 states,  according to officials. NCDC officials also told us that they created  composite stations to achieve a minimum record length when no  stations in a particular geographic area had been collecting  temperature records as long as they sought. According to NCDC  officials, they create a composite station by combining data from one  or two stations that have closed with data from an active station in the  same area whose temperature records overlap in time with records  from the closed station or stations and continue to the present. NCDC  officials told us that they compare the stations’ overlapping  temperature trends before creating a composite to help ensure that  the climates at the stations are similar. According to NCDC  documents, the initial selection of USHCN stations in 1987 included  84 composite stations, and, as of the latest revision to the network in  2009, the number of composite stations had increased to 208, largely  in response to station closures. Our analysis of the 1,218 stations that  make up the USHCN as of the latest revision in 2009, including  composite stations, found that NCDC has largely achieved its desired  record length. Specifically, as of 2010, over 85 percent of the stations  had a record length dating back more than 100 years, and another  14 percent had temperature record lengths of 76 to 100 years. Less  than 1 percent of stations had record lengths of 75 or fewer years.    Extent of missing data. NCDC officials told us that they also attempted  to select USHCN stations with limited periods of missing data but that  they often had to select stations with incomplete temperature records,  including stations that were missing data for multiple years, because  few stations have complete records. For example, about half the data  from the Little Falls Mill Street station, located in upstate New York,  are missing. The station’s record has data for a few years in the 19th  century, but data in the intervening years are sparse, with frequent  gaps in the middle of the 20th century, according to a 1990 NCDC  report on the USHCN. According to NCDC, various factors result in  missing data, such as periods when a volunteer observer is not  available or when instruments malfunction and need to be repaired.  Our analysis of temperature records shows that only 24 of the 1,218  USHCN stations (about 2 percent) have complete temperature data  from the time they were established through 2010; the remaining  98 percent of stations are missing an average of 5 percent of  temperature data. To generate uninterrupted temperature records,  NCDC uses estimates for the missing data based on records from  nearby stations in the larger set of Cooperative Observer Program  weather-monitoring stations. For example, according to agency  officials, NCDC used this process to fill in missing data for the Little  Falls Mill Street station. According to NCDC officials, filling in missing  data ensures that temperature records from all areas of the  contiguous 48 states are represented when the agency uses the  USHCN to identify national temperature trends.    Stability of measurement conditions. A final consideration in selecting  USHCN stations was NCDC’s desire to maximize the stability of  measurement conditions—such as station location, type of  temperature-measuring instrument, and time of day when  observations were recorded—because such stability makes it easier  to discern actual temperature trends at a station. NCDC officials told  us that, like stability in other measurement conditions at USHCN  stations, stability in siting conditions facilitates officials’ ability to use  temperature data to accurately identify long-term warming and cooling  trends, even if those conditions do not meet NWS siting standards.  Most stations with long temperature records, however, are likely to  have undergone multiple changes in measurement conditions. For  example, according to NCDC’s records, the Reno, Nevada, USHCN  station was originally located at an NWS weather forecast office  before being moved in the mid-1930s to an airport and then again in  the 1990s to another location at the same airport. According to NCDC,  such changes in measurement conditions may cause a rise or drop in  the temperatures recorded at stations, which could affect the  temperature trends identified using the USHCN. For example, NCDC  has studied the impact of a gradual change in the time that observers  record temperature measurements from afternoon to morning  observation times and concluded that the change has obscured the  warming trend across the contiguous 48 states, which would  otherwise have appeared more pronounced. NCDC officials told us  that they use statistical methods to identify significant shifts in  temperature data unrelated to actual trends in temperature and to  adjust the data to remove such shifts. According to NCDC officials,  all 1,218 USHCN stations have undergone at least one change in  measurement conditions requiring such an adjustment, with an  average per station of four to five changes.
NCDC officials acknowledged that a greater degree of stability of  measurement conditions than typically found at USHCN stations would be  preferable. As a result, NCDC has established a new network of surface  weather-monitoring stations specifically to monitor the nation’s climate— the U.S Climate Reference Network—and is establishing a second one— the U.S. Regional Climate Reference Network (see app. II). According to  agency officials, they have developed criteria for selecting locations for  stations in the new networks to help ensure a greater degree of station  stability in comparison with the USHCN and reduce the need to identify  and remove shifts in temperature records that are unrelated to actual  warming or cooling. NCDC officials told us these new networks can be  used to construct a continuous temperature record with the USHCN once  the new networks have a sufficient period of overlap with the USHCN to  allow for a comparison of temperature trends.
section_title: Siting Conditions at Weather-Monitoring Stations Played a Limited Role in Selections for the USHCN
paragraphs: The extent to which stations met specific NWS siting standards played  only a limited role in the initial selection of stations for the USHCN in 1987  and when the makeup of the USHCN was revised in 1996 and 2009,  according to NCDC officials. 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. For  example, NCDC has included in the USHCN the Central Park station in  New York City, which has a temperature record dating to 1876 and has  had limited moves, even though current information on the station shows  it is encircled by trees. NCDC officials said that, in an effort to consider  some information on siting as part of the process of selecting stations,  they obtained recommendations from state climatologists and others with  detailed knowledge of the siting conditions at stations in their states.
NCDC officials told us that another reason siting conditions played a  limited role in their initial selection of USHCN stations in 1987 was that  NCDC had limited information about siting conditions at the time. NCDC  officials said they generally did not visit stations to examine siting  conditions, except for a few stations near their headquarters in Asheville,  North Carolina, because it was not feasible to do so with so many stations  distributed nationwide. In addition, according to NCDC officials, when  they first considered stations for inclusion in the USHCN, they had more  limited electronic access to station histories and information about siting  conditions than they do today. NCDC officials also said that the station  histories they did have may not have included all relevant siting  information, such as proximity to obstructions.
According to NCDC officials, they may have kept some weather-monitoring  stations that do not meet specific NWS siting standards out of the USHCN  by generally excluding many sites in large urban areas. For example,  weather-monitoring stations located in large urban areas may be too close  to extensive paved surfaces or obstructions to meet specific NWS siting  standards. Nevertheless, individual stations were excluded because they  were located in a large urban area, not because they did or did not meet a  specific NWS siting standard. Similarly, NCDC officials told us that many  stations with the longest records were not selected because NCDC  considered the temperature records for these stations to have been  affected by the stations’ location in or adjacent to large urban areas.  Nevertheless, the officials told us, NCDC made exceptions and selected  some stations in or near large urban areas. According to NCDC’s 1987  report on its initial designation of the USHCN, 70 percent of the selected  stations were located in areas with populations of less than 10,000 in the  1980 census, and 90 percent were located in areas with populations of less  than 50,000.
section_title: USHCN Stations Meet Siting Standards and Management Requirements to Varying Degrees
paragraphs: According to our survey of NWS weather forecast offices, close to half of  USHCN stations do not adhere to one or more siting standards. Weather  forecast offices cited a variety of factors that contributed to stations not  adhering to siting standards, such as the use of temperature-measuring  equipment that limits NWS’s ability to locate stations so that they adhere  to the 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.
subsections: section_title: Close to Half of USHCN Stations Do Not Meet NWS Siting Standards
paragraphs: 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. This percentage is  slightly higher than the percentage not meeting the standards in the larger  set of Cooperative Observer Program stations in the contiguous 48  states, of which the USHCN is a part. Specifically, according to our  survey responses, about 37 percent of the active Cooperative Observer  Program stations in 2010 did not adhere to one or more of the  standards.
The two standards most commonly cited by weather forecast offices as  unmet by USHCN stations were distance to obstructions, such as  buildings and trees, and distance to extensive concrete or paved surfaces  (see fig. 3). According to weather forecast offices’ survey responses, only  a small fraction of the stations did not adhere to the other siting  standards, including that temperature-measuring instruments be mounted  4 to 6 feet off the ground. In particular, according to our survey  responses, only five active USHCN stations (less than 1 percent) were  located on a rooftop.
We also visited a nonprobability sample of 8 weather forecast offices and  19 stations in the USHCN that are managed by these offices. During  these visits, we observed stations that were located closer to obstructions  or to extensive concrete or paved surfaces than specified in the siting  standards, although the degree to which the stations did not adhere to the  standards varied. For example, figure 4 shows 2 stations that did not  meet the siting standards. One station was located too close to a building  and trees at a wildlife preserve in an otherwise relatively undeveloped  area, but the other station was located in a relatively urban area and  surrounded by a parking lot, building, and street.
The two factors most commonly cited by NWS weather forecast offices  responding to our survey as contributing to USHCN stations not adhering  to one or more of the siting standards were (1) NWS’s preference for  locating stations at sites that provide a high degree of station stability and  data continuity, even if these sites do not adhere to standards, and (2) the  use of temperature-measuring equipment that limits NWS’s ability to  locate stations so that they adhere to the standards (see fig. 5):    Preference for station stability and data continuity. In our survey of  weather forecast offices, the most commonly cited factor contributing  to USHCN stations not meeting the siting standards was a preference  for locating stations at sites that provide stability and continuity of  data. For example, officials in the Tampa weather forecast office told  us that one USHCN station that was located in a downtown area and  did not meet siting standards has a temperature record that begins  before 1895, the first year of data used in the USHCN. They said they  could either keep this station open or close it, since there were no  other options that met the standards either on the current observer’s  property or in the surrounding area. They chose to keep the station  open because of its long temperature record.    Limitations due to temperature-measuring equipment. 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.  Weather forecast office staff must dig trenches for the cables, and  paved surfaces such as sidewalks and driveways, as well as the cost  of cable for trenching, can limit the length of trenches and  consequently the ability to locate stations so that they adhere to the  siting standards. According to data from NCDC, about three-quarters  of stations in the USHCN use such equipment.
NWS headquarters officials told us they hope to replace cabled  temperature-measuring equipment with new wireless equipment that can  more easily be located in accordance with siting standards. Specifically,  the NWS headquarters office with overall responsibility for the  Cooperative Observer Program has developed a draft plan for the  program that envisions replacing current equipment with wireless  equipment. The draft plan does not specify the number of stations where  equipment will be replaced but rather calls for evaluating weather- monitoring stations to determine if they meet the siting standards,  identifying candidate stations for installing wireless equipment or  relocating them to meet siting standards, and identifying stations that are  candidates for being closed. NWS officials said, however, that the agency  has not yet approved the plan for implementation. We did not specifically  ask about wireless equipment in our survey, but 35 weather forecast  offices entered comments expressing support for replacing the  temperature-measuring equipment currently used at weather-monitoring  stations with wireless equipment. Twenty of the offices specifically cited  the ability to improve station siting as the reason for making this change.  Comments entered by weather forecast offices on our survey, as well as  the draft plan, also cited greater ease of installation and maintenance as  additional benefits of wireless equipment. For example, installing wireless  equipment would not require digging a trench for a cable.
Even if NWS approves the draft plan, the use of wireless equipment may  not address all siting issues. First, according to NWS officials,  commercially available wireless equipment has not yet been developed  that meets NWS standards for temperature observations at a cost that is  feasible for use at weather-monitoring stations nationwide. The NWS  official in charge of monitoring the development of wireless equipment  said, however, that such equipment would most likely be available within  5 years. Second, the use of wireless equipment, when available, would  not allow NWS to improve siting at all stations that do not currently meet  the standards. For example, the observers’ properties at some of the  stations we visited were too small to allow any temperature-measuring  equipment to be placed far enough from buildings or other obstructions to  meet the siting standards, regardless of whether the equipment was  wireless or cabled. NWS officials acknowledged that the use of wireless  equipment would improve station siting but not eliminate all stations that  currently do not meeting siting standards.
NWS officials also described a wide range of other factors contributing to  stations not adhering to siting standards. These include  the difficulty of recruiting new volunteer observers at sites that meet  standards, particularly as the nation’s population has become more  mobile and thus less apt to serve as long-term observers;    properties that may be too small or have trees or other features that  make it difficult to locate instruments as far from obstructions as the  standards specify;  the reluctance of observers to allow equipment sited in a location on  their property that would meet the standards;  changes to the observer’s property (e.g., growth of trees) or  urbanization of the surrounding area that can cause the stations to not  meet standards; and    natural geographic features in certain areas, such as heavily forested  or mountainous terrain, that can hamper the ability to meet the  standards.
section_title: NWS Weather Forecast Offices Have Generally but Not Always Met the Requirement to Annually Inspect Stations and Periodically Update USHCN Station Records
paragraphs: Our review of files for USHCN stations at 8 weather forecast offices, as  well as our survey results, show that the offices have generally but not  always met the requirement to annually inspect stations to maintain  temperature-measuring equipment and determine if changes have  occurred requiring station records to be updated, such as changes to  siting conditions. Our file reviews also show that the offices generally but  not always met the requirement to periodically update station records,  even if no changes had taken place at a station. 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. Any information NCDC has about these conditions, according  to agency officials, can be used in conjunction with its statistical methods  to identify significant shifts in a station’s temperature data that are  unrelated to actual warming or cooling trends and to adjust the data to  remove such shifts.    Annual inspections. The results of our survey indicate that in 2010,  102 of 114 weather forecast offices met the annual inspection  requirement for stations in the USHCN. According to our survey  results, 12 offices did not meet the requirement at a total of  35 stations. In reviewing files at the 8 weather forecast offices we  visited, we also found instances where the annual inspection  requirement was not met in 2008 and 2009. Specifically, the results of  our file reviews show that 3 of the 8 offices did not meet the annual  inspection requirement for five stations in 2008, and 1 office did not  meet the requirement for one station in 2009. In contrast, for the  stations where the requirement had been met, the weather forecast  offices had frequently conducted multiple inspections during a year.  For example, office staff may have visited a station multiple times to  repair equipment, to temporarily relocate temperature-measuring  instruments to allow for construction at the observer’s property, or to  meet the requirement for semiannual inspections of stations that also  record precipitation.    Station record updates. Until 2005, NWS required that station records  be updated at least once every 10 years. At that time, NWS changed  the requirement to once every 5 years. In reviewing files at the 8  weather forecast offices we visited, we found that two of the 8 offices  had consistently met the requirement to update station records within  5 years. In contrast, at two of the other offices, the time between  updates for four stations was over 10 years. At the remaining four  offices, the time between updates for one or more stations was over 5  years but less than 10 years. For example, one office did not update a  record dated February 2002 until January 2011—almost 9 years after  the previous update. When the weather forecast offices updated  records, the types of changes they documented included those that  can cause shifts in temperature data unrelated to any actual  temperature change, including replacement or relocation of  temperature-measuring equipment, changes in time of observation,  and descriptions of obstructions.
Through our survey and visits to 8 weather forecast offices, weather  forecast office officials identified a number of challenges to their ability to  ensure that station records are updated and to carrying out other  responsibilities for managing stations in the Cooperative Observer  Program, including those in the USHCN. In our survey, the most  frequently cited challenge was that weather forecast offices rely on staff  assigned to manage the stations to also assist with other office  responsibilities. Competing mission requirements at the offices was a  closely related and often-cited challenge. For example, weather forecast  offices operate 24 hours a day, and office officials explained that staff  assigned to manage the stations may also be expected to work shifts,  which limits the time they can visit the stations. Some weather forecast  offices we visited told us that turnover and reductions in the number of  staff assigned to the Cooperative Observer Program results in the loss of  institutional knowledge needed to manage weather-monitoring stations.  Weather forecast offices, particularly those with large areas to cover, also  identified long driving distances to stations as a challenge. For example,  officials at one office we visited told us that completing the required  annual station visits requires driving 17,000 miles per year; that the  round-trip drive to some stations takes longer than 10 hours, leaving  limited time to maintain equipment or install equipment at new stations;  and that during the winter, some stations are inaccessible.
section_title: NWS Does Not Centrally Track Whether USHCN Stations Meet Siting Standards or Have a Policy for Addressing Stations That Do Not Meet the Standards
paragraphs: 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 also does not have an agencywide policy on what actions  to take at stations that do not adhere to siting standards, which creates  the potential for inconsistency in how weather forecast offices address  such stations. The lack of centralized electronic tracking of performance  information for the USHCN and the lack of an agencywide policy on the  actions to take at stations that do not meet siting standards limit NWS’s  ability to manage the USHCN in accordance with performance  management guidelines and federal internal control standards.
subsections: section_title: NWS Does Not Have Centrally Available Information to Assess USHCN Performance
paragraphs: NWS’s siting standards for weather-monitoring stations and the  requirement that station records be updated at least once every 5 years in  effect establish goals for each weather forecast office to meet. NWS does  not, however, centrally capture data on the extent to which stations in the  Cooperative Observer Program and the USHCN meet its siting standards  and station record update requirement. NWS has an information system it  uses to help manage weather-monitoring stations, but the system has  several limitations. The information system allows the agency to record  basic identifying information about the stations and the conditions under  which volunteer observers record weather observations, including some  information about siting conditions and the dates of station record  updates. According to NWS officials, however, the agency did not design  the system to centrally track adherence to siting standards or the  requirement to update station records at least once every 5 years. As a  result, NWS is limited in its ability to use its information system to track  USHCN performance information.
The information system NWS uses to track information related to  Cooperative Observer Program stations, including those selected for the  USHCN, has the following specific limitations:    Limited information on adherence to station siting standards.
According to NWS headquarters officials, they cannot query their  information system to identify the specific weather-monitoring stations  that do not meet siting standards or the total number of stations that  do not meet standards. For example, in 2009, NCDC requested that  NWS verify siting conditions at USHCN stations for a study evaluating  the effects of siting conditions on temperature trends. NWS  headquarters did not have a way to easily gather this information and  instead had to direct its regional offices to have weather forecast  office staff verify siting conditions at the stations. According to NWS  officials, weather forecast office staff did not make special visits to the  stations to gather the information requested by NCDC, as these  stations might not have been on their immediate visit schedule, but  reviewed files instead.
Incomplete information on siting conditions. NWS guidance for using  the information system directs weather forecast offices to enter  descriptions of obstructions at weather-monitoring stations. We found  that in some cases, however, such descriptions may not accurately  reflect whether temperature-measuring equipment meets the siting  standard related to obstructions. This discrepancy can arise because  NWS guidance directs weather forecast offices to describe  obstructions in relation to a station’s rain gauge. We found that  obstructions to temperature measuring-equipment can differ from  those to the rain gauge, depending where the two instruments are  located. For example, the record for one USHCN station we visited  did not include any obstructions because the rain gauge was on a  rooftop where there were no obstructions. The station’s temperature- measuring equipment, however, was at ground level and surrounded  by buildings on three sides and, as a result, did not meet NWS’s  standards for siting temperature sensors. (The station’s temperature- measuring equipment can be seen in fig. 6.) In addition, NWS  guidance for using the information system does not direct weather  forecast offices to enter descriptions of other conditions that might  indicate whether specific siting standards are being met, such as  proximity to extensive concrete or paved surfaces.    Limited ability to track whether the requirement to update station  records is being met. The NWS information system is designed to  allow weather forecast office staff to enter the date each station  record is updated and to store previous versions of station records.  NWS officials stated, however, that the information system is not set  up to centrally track the performance of weather forecast offices in  updating station records within the required 5-year time frame. In  addition, the system is not set up to allow NWS to notify weather  forecast offices when station records are nearing the 5-year mark and  need to be updated. NWS regional offices and weather forecast  offices are instead responsible for tracking the status of updates. For  example, an official at one office we visited told us that he sometimes  forgets to update station records within the 5-year time frame but that  the NWS regional headquarters keeps track of the requirement.
Inconsistent identification of stations included in the USHCN. The  NWS information system includes information about all stations in the  Cooperative Observer Program, including those designated by NCDC  as part of USHCN, but NWS does not consistently use the system to  identify USHCN stations. Specifically, station records allow weather  forecast offices to indicate whether stations are part of the USHCN,  but offices had done so in only some of the station records we  reviewed. As a result, NWS headquarters officials cannot use their  information system to determine which stations NCDC has designated  as part of the USHCN. Officials at some of the weather forecast  offices we visited were also unsure which of the stations they manage  had been designated as part of the USHCN. According to NCDC  officials, it is important that weather forecast offices have the ability to  determine which stations belong to the USHCN so that they can set  appropriate priorities for the maintenance, repair, and replacement of  temperature-measuring equipment at these stations.
Our work related to the Government Performance and Results Act of  1993 and the experience of leading organizations have shown the  importance of developing program performance goals that identify desired  results of program activities and reliable information that can be used to  assess results. NWS headquarters officials we spoke with  acknowledged the need to centrally track performance information related  to the management of Cooperative Observer Program stations, which  includes those selected for the USHCN. The officials said they only  recently began tracking the requirement that weather forecast offices  inspect stations at least once annually. According to these officials, they  selected annual station inspections as a performance indicator because  the inspection requirement is easy to track using the current information  system for managing the stations. NWS provided us with summary data  on inspections for all stations in the Cooperative Observer Program,  including USHCN stations. The data show that the percentage of stations  for which weather forecast offices met the annual inspection requirement  increased from 70 percent in 2005 to 80 percent in 2010.
NWS headquarters officials also told us that the agency has begun  upgrading its current information system and that they are considering  options to notify weather forecast offices when updates of station records  are overdue and to better track adherence to siting conditions. The  officials said they hope to complete the upgrade by the end of fiscal year  2013, depending on the availability of funding. Options being considered  for tracking siting conditions include photographs of stations and the use  of a rating scale to summarize the extent to which stations adhere to  siting standards, similar to the rating scale created for the newer networks  developed specifically for climate monitoring (see app. II for further  details). According to our survey results, 63 percent of weather forecast  offices believe that the use of photographs in the NWS information  system would be either very helpful or extremely helpful in evaluating  stations’ adherence to siting standards. In addition, 52 percent of the  offices responded that the option to check a box in a station’s electronic  record to indicate that it does not adhere to the standards would be either  very helpful or extremely helpful. Some offices also suggested other tools  they would consider helpful in evaluating siting conditions at stations,  such as the use of commercially available satellite imagery and maps.
section_title: NWS Does Not Have an Agencywide Policy to Address Stations That Do Not Adhere to Siting Standards
paragraphs: 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. Without an agencywide policy, weather forecast  offices do not have a basis for making consistent decisions about what  actions to take at USHCN stations that do not adhere to siting standards.
NWS headquarters officials we spoke with acknowledged that they had  not developed an agencywide policy on the actions, if any, that weather  forecast offices should take to address stations that do not adhere to  siting standards. They said they recognized the need to develop an  agencywide policy and that, in the absence of such a policy, decisions on  how to address stations that do not meet siting standards are up to  individual weather forecast offices. For example, they said weather  forecast offices might consult with NCDC or state climatologists when  deciding whether to close stations that do not meet siting standards, but  that such outreach is not required.
In the absence of an agencywide policy, the NWS western regional office  directed weather forecast offices in the region to stop submitting data to  NCDC from stations with “egregious” siting conditions in a format that  would allow NCDC to use these data when analyzing long-term  temperature trends. The meaning of “egregious” was not defined and was  left to each weather forecast office to interpret. According to NWS  officials, none of the other three regional offices in the contiguous United  States have developed a similar policy. According to the western regional  manager responsible for the Cooperative Observer Program, the region’s  policy affected about a dozen stations, which had not been designated as  part of the USHCN. Through our visits to weather forecast offices,  however, we found that, even in the western region, the offices did not  consistently implement the region’s policy. In particular, an official at one  of the two offices we visited in the region told us he did not follow the  policy because doing so would have affected the majority of stations in  his state.
NCDC officials told us that, as NWS develops a policy regarding how to  address stations in the Cooperative Observer Program (including those  designated as part of the USHCN) that do not meet siting standards, it  should consider how NCDC uses the temperature data from the stations.  Because the data from USHCN stations are used to identify long-term  climate trends and the stations were thus selected in part on the basis of  the stations’ stability of measurement conditions and continuity of data,  NCDC officials said they would caution NWS against relocating or closing  stations that do not meet siting standards. NCDC officials said they would  consider closing a station only in certain situations, such as an observer  not following NWS guidelines when recording weather observations.
section_title: Conclusions
paragraphs: Given the importance of data from the USHCN in monitoring and in  formulating public policy related to climate change, it is important that the  public and policymakers have confidence that the network is being  managed effectively. NWS has developed station siting standards and  management requirements for the USHCN, and performance  management guidelines dictate that NWS should gather data on the  extent to which these standards are being met. But NWS’s information  system does not centrally capture such information. As a result, the  agency cannot easily measure the USHCN’s performance against its  siting standards and management requirements. Without more complete  data on siting conditions, including when siting conditions change, it is  difficult for agency management to assess the extent to which the stations  meet its siting standards. Similarly, NWS does not have easily accessible  data on when station records were last updated for monitoring whether  the records are being updated at least once every 5 years as the agency  requires. In addition, although federal internal control standards call for  agencies to develop policies to maintain control over program activities,  NWS has not established agencywide policy for what to do when, over  years and decades, stations no longer adhere to its siting standards  because conditions have changed. 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. As a result, without a policy with actions for  all offices to follow, weather forecast offices may be taking different  approaches to address stations that do not meet siting standards.
section_title: Recommendations for Executive Action
paragraphs: 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.    Develop an NWS agencywide policy, in consultation with NCDC, on  the actions weather forecast offices should take to address stations  that do not meet siting standards.
section_title: Agency Comments and Our Evaluation
paragraphs: We provided a copy of our draft report to the Department of Commerce  for review and comment. In written comments from the department,  NOAA agreed that it can improve its ability to manage the USHCN in  accordance with performance management guidelines and federal  internal control standards. NOAA also agreed with our two  recommendations. Regarding our first recommendation, NOAA stated  that NWS has begun the planning process to upgrade the existing  information system that captures data for managing Cooperative  Observer Program stations, including those that are a part of the USHCN.  According to NOAA, the upgrade will include the ability to capture more  complete data on siting conditions and to determine if a station’s record  has been updated in the last 5 years. Regarding the second  recommendation, NOAA said that NWS will work with NCDC to develop a  policy to assist weather forecast offices in taking action on stations that  do not meet siting standards.
NOAA also stated that it understood that, given the scope of our review,  we did not assess the effect of stations not meeting siting standards on  the reliability of the agency’s analysis of temperature trends.  Nevertheless, NOAA added that it was important for our findings to  include a discussion of the published peer-reviewed studies that have  explicitly examined the USHCN’s data quality and its effects on the  reliability of NOAA’s temperature trend data. We did not include such a  discussion in our report because this issue was outside the scope of our  work. We did, however, reproduce NOAA’s list of relevant studies on this  topic together with its comments. NOAA also provided technical  comments, which we incorporated into the report as appropriate. NOAA’s  comments are reproduced in appendix III.
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section_title: Appendix I: Scope and Methodology
paragraphs: To determine how the National Oceanic and Atmospheric Administration  (NOAA) selected stations for the U.S. Historical Climatology Network  (USHCN) from the larger set of existing stations in the Cooperative  Observer Program network, we reviewed documents from NOAA’s  National Climatic Data Center (NCDC) describing the selection process,  interviewed NCDC officials, and analyzed NCDC data on stations in the  USHCN. Specifically, we reviewed documents written by NCDC officials  to identify the factors the agency considered important for monitoring  long-term temperature trends, and we interviewed NCDC officials  regarding these factors, as well as how they applied them in the selection  process. We also obtained data from NCDC on the geographic  distribution of USHCN stations across the contiguous 48 states and the  length and completeness of the stations’ temperature records. The data  we obtained and analyzed came from NCDC’s version 2 of the USHCN.  We assessed the reliability of the data by electronically testing them and  comparing selected samples to data from other NOAA sources to check  for obvious errors in accuracy and completeness. We also reviewed  information about the data and the systems used by NCDC to produce  the data, interviewed NCDC officials knowledgeable about the data, and  worked with officials to clarify inconsistencies before using the data in our  analyses. We determined that the data were sufficiently reliable for  reporting on the extent to which USHCN stations met the factors NCDC  considered important in selecting the stations.
To examine the extent to which USHCN stations meet National Weather  Service (NWS) siting standards and management requirements for  weather-monitoring stations, we developed and administered a survey of  meteorologists-in-charge at the 116 NWS weather forecast offices  responsible for managing stations in the network. Our questionnaire  included questions about adherence to siting standards, reasons for  stations not adhering to the standards, and general management  challenges. The survey was Web based and accessible through a secure  server. On February 7, 2011, we sent an e-mail notification to the 116  meteorologists-in-charge describing the survey and notifying them that it  would be activated on the Internet shortly. On February 9, 2011, we  formally activated the survey and sent another e-mail containing a link to  the survey along with each respondent’s unique username and password.  We sent follow-up e-mail messages on February 16, 2011, and February  24, 2011, to those who had not yet responded. Then, starting on March  11, 2011, we contacted the remaining nonrespondents by telephone or   e-mail. The questionnaire was available online until March 23, 2011. By  that date, the surveys were completed by all 116 weather forecast offices,  for a response rate of 100 percent.
Because our survey covered all weather forecast offices in the contiguous  48 states, not a sample of them, it was not subject to sampling error.  Surveys are, however, subject to nonsampling errors. For example, how a  particular question is interpreted, sources of information available to  respondents, and how the data are entered in a database or are analyzed  can introduce unwanted variability into survey results. We took steps in  developing the survey, collecting the data, and analyzing them to  minimize such nonsampling errors. For example, GAO survey specialists  designed the questionnaire in collaboration with GAO staff who had  subject-matter expertise. In addition, we conducted four pretests of the  draft questionnaire to ensure that the questions were clear and  unambiguous, terminology was used correctly, the questionnaire did not  place an undue burden on agency officials, the information could feasibly  be obtained, and the survey was comprehensive and unbiased. We  conducted each of the four pretests over the telephone with one or more  NWS officials from each of the four NWS regions in the contiguous United  States. On the basis of the feedback we received, we made changes to  the content and format of the survey after each of the four pretests. When  we analyzed the data, an independent GAO analyst checked all computer  programs. Since this was a Web-based survey, respondents entered their  answers directly into the electronic survey, eliminating the need to key  data into a database, thus minimizing data entry errors.
Our survey results are also subject to errors made by weather forecast  office staff regarding the number of stations they reported as not adhering  to siting standards. For example, one weather forecast office indicated in  its survey response that one USHCN station in its area was on a rooftop,  but office staff later told us that the survey response was wrong and that  none of its USHCN stations is located on a rooftop. In addition, the  number of stations reported by weather forecast offices as not adhering to  siting standards is subject to the staff’s interpretation of NWS’s siting  standards. For example, it is a matter of interpretation and judgment by  NWS staff whether objects surrounding a station, such as trees or  structures, are considered to be obstructions and thus whether a station  is considered to meet or not meet the siting standards. The response to  our survey from one weather forecast office we visited indicated that the  temperature-measuring equipment at only one of its USHCN stations was  closer to an obstruction than specified in the siting standards. We  observed obstructions at all three stations we visited, however, and the  records for these stations also listed obstructions.
In calculating the percentages of the total number of active stations that  met the specific criteria we asked about in our survey questions, we did  not use responses from weather forecast offices that provided incomplete  or inconsistent information. Depending on the percentage being  calculated, we did not use responses from at most 6 of the 116 offices.  For example, we did not use responses from 3 offices when calculating  the percentage of active USHCN stations that did not adhere to one or  more of the siting standards, and we did not use responses from 5 offices  when calculating the percentage of active Cooperative Observer Program  stations not adhering to one or more of the standards.
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 ensure geographic distribution in the weather forecast offices  we visited, we selected two offices in each of the four NWS regions in the  contiguous United States, and we selected the specific offices we visited  to ensure a range of sizes in terms of the offices’ forecast areas. We also  selected offices with differing structures for supervising staff assigned to  manage the Cooperative Observer Program and with a range of other  programs the offices are responsible for, such as marine forecasts. To  examine adherence to siting standards for weather-monitoring stations,  we observed siting conditions at a nonprobability sample of 19 USHCN  stations. We selected stations to visit to ensure variety in the type of  temperature-measuring equipment used at the stations and other factors  that could affect siting conditions. During the station visits, we developed  and used a checklist that tracked how well the conditions of the site met  what was recorded in the stations’ records. In addition, we reviewed files  on USHCN stations at each of the weather forecast offices we visited. We  reviewed records and annual inspection reports from a total of 81 USHCN  stations. We entered information from the records and inspection reports  into a database to capture information on the extent to which weather  forecast offices adhered to the requirements to update station records  and conduct annual inspections, among other things. Because we used a  nonprobability sample to select weather forecast offices and USHCN  stations to visit, the information we obtained from these visits cannot be  generalized to other weather forecast offices or USHCN stations. The  visits instead provided us with information on the perspectives of various  participants in the weather forecast offices about managing weather- monitoring stations and examples of station siting conditions.
To gather additional information on the extent to which USHCN stations  meet NWS siting standards for weather-monitoring stations, we also  reviewed academic literature that addressed issues and concerns related  to siting of weather-monitoring stations, including those in the USHCN.  We also reviewed NWS’s policy directives related to station siting and  interviewed officials in NWS headquarters, regional offices, and weather  forecast offices who were responsible for managing the Cooperative  Observer Program. In addition, we interviewed the person at the NWS  training center responsible for training NWS staff on management and  operation of the Cooperative Observer Program and individuals who have  raised concerns about the extent to which stations in the USHCN are  meeting siting standards.
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. In particular, we evaluated the types of data that are  captured in NWS’s information system for managing weather-monitoring  stations—the Cooperative Station Service Accountability system. We also  interviewed NWS officials responsible for managing the USHCN, as well  as NCDC officials; reviewed NWS policy directives, briefings, and  memorandums related to managing the network; and examined data on  the extent to which NWS conducted the required annual inspections of  weather-monitoring stations. To determine the extent to which NWS has  established a policy to address stations that do not adhere to siting  standards, we reviewed NWS documents, such as agency directives,  memos, briefings on the future of the Cooperative Observer Program, and  an executive summary for a draft strategic plan for the program. In  addition, we interviewed NCDC officials and NWS officials from regional,  headquarters, and weather forecast offices and from the Cooperative  Observer Program training center.
section_title: Appendix II: Other National Climate Networks
paragraphs: Since 2001, NOAA has supported establishment of two new networks of  climate monitoring stations. The first to be established, the U.S. Climate  Reference Network, is intended to detect indications of climate change at  a national scale. This network consists of 114 stations in the contiguous  48 states, and NOAA has plans to expand the network to include stations  in Alaska. The purpose of the second new network, the U.S. Regional  Climate Reference Network, is to detect indications of climate change at a  regional rather than national scale. As of July 2011, this network  consisted of 63 stations in the southwestern United States, and NOAA  hopes to complete the installation of stations for the network across the  contiguous 48 states by about 2020, depending on the availability of  funding. According to NOAA, once both networks are fully established,  about 538 locations in the contiguous United States will have either a  U.S. Climate Reference Network station or a U.S. Regional Climate  Reference Network station.
The station-siting standards for the two new networks have similarities to  the siting standards established for the Cooperative Observer Program  and that also apply to the USHCN, such as installation over level terrain  and not on rooftops. The new networks also have differences, including  instances where the siting standards for the new networks are more  stringent. For example, the standards for the U.S. Climate Reference  Network call for stations to be located farther from concrete or paved  surfaces than specified in the standards for stations in the USHCN. 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. For example, the use  of automated equipment, as well as solar power at many stations, allows  for greater flexibility in locating stations in comparison with NWS weather- monitoring stations that rely on volunteer observers and equipment  connected by a cable to an indoor readout device. Similarly, to the extent  possible, NOAA has placed a priority on locating stations for the new  networks on public lands, such as national and state parks. According to  NOAA, in comparison with the properties of volunteer observers, such  locations have a higher probability of continuing in their present condition  without major changes for long periods of time (50 to 100 years). Figure 7  depicts a station in the U.S. Climate Reference Network.
NOAA has also established a process to evaluate and select potential  sites for stations in the new networks. For example, selecting stations for  the U.S. Regional Climate Reference Network includes field and desk  surveys, which involve collecting information about the site’s condition  from photographs and other sources; evaluation of the surveys by a site  selection panel; a vote among panel members to decide among  candidate locations; and final approval or disapproval of panel  recommendations by a site selection lead. See table 1 for differences in  the siting standards applied to the USHCN and the new climate networks.
section_title: Appendix III: Comments from the Department of Commerce
section_title: Appendix IV: GAO Contact and Staff Acknowledgments
subsections: section_title: GAO Contact
section_title: Staff Acknowledgments
paragraphs: In addition to the contact named above, Stephen D. Secrist (Assistant  Director), Richard Bulman, William Carrigg, Joanna Chan, Ellen W. Chu,  Joseph Cook, Alysia Davis, N’Kenge Gibson, Stuart Kaufman, Cheryl  Peterson, Anne Rhodes-Kline, and Jerome Sandau made key  contributions to this report.