The 1997 Conference on the World Climate Research Programme to the Third Conference of the Parties of the United Nations Framework Convention on Climate Change concluded that the ability to monitor the global climate was inadequate and deteriorating. Consequently, the National Research Council (NRC) undertook an assessment of the U.S. climate observing capacity. The NRC recommended that a system of network performance measures be developed and monitored on a regular basis to avoid the discovery of observing network problems years after their occurrence (during, for example, a major environmental assessment). The NRC further recommended that an institutional infrastructure be developed to assess the quality of data sets operationally. Such an infrastructure could facilitate the correction of problems as they occur and help avoid long-term negative impacts to the climate record.

To address the NRC recommendations a project known as the Health of the Networks was established at NOAA’s National Climatic Data Center. Currently, the “health” of three observing networks is monitored using various performance indicators. While the suite of indicators varies from network to network, special attention is paid to changes in baseline performance and to the detection of undocumented changes. Examples of performance indicators are provided and a simple framework permitting feedback between the monitoring system and network managers is discussed.