GCOS has two primary meteorological networks: The GCOS Surface Network (GSN) and the GCOS Upper Air Network (GUAN). While designed for global climate monitoring, these networks have not achieved their potential (GCOS, 2003). To help make them more useful for climate change analyses, several different GCOS Centers have been established including Monitoring, Archive, Analysis and Lead Centers (Daan, 2002; Commission for Basic Systems, 2002). The U.S. National Climatic Data Center (NCDC) has served as GSN and GUAN Archive and Analysis Centers for several years and has more recently formally accepted the role of the World Meteorological Organization (WMO) Commission for Basic System (CBS) Global Climate Observing System (GCOS) Lead Center. As a Lead Center, NCDC has accepted some additional obligations but also gained an important tool to use in its effort to improve the networks. This paper will report on the Lead Center activities and document the progress and status of the GSN and GUAN.

CBS specifically authorized GCOS Lead Centers to contact countries. In the past, GCOS country contacts went formally through WMO Secretary General. During the past year, NCDC’s Greg Hammer has directly emailed both GCOS Points of Contact and, for countries that have not provide Points of Contact, countries’ Permanent Representative to WMO seeking both data and metadata. As most GUAN data are already available in the NCDC GUAN archive, his main GUAN related quest has been to acquire metadata that indicate changes in the radiosonde observations, such as changes in the type of sondes flown, that have been made since the Gaffen survey in the early 1990s (Gaffen, 1993; Gaffen, 1996). These metadata are having an immediate direct impact on global climate monitoring activities using radiosonde data (Free et al., 2004). For the GSN, his focus has been primarily on encouraging countries to send in their data so they can be incorporated into the GSN archive and provided to users. He has had several notable successes, but many countries have not yet sent in their data.

In addition to seeking out new data directly from the countries, the GSN is being improved in two important ways. The first is that for countries that have not provided their data or provide very little data (e.g., one country only provided 6 years of GSN daily data), NCDC supplements the GSN with digital data which NCDC has and is allowed to release. The primary focus of this work has involved the Global Historical Climatology Network (GHCN) – Daily dataset, which Byron Gleason is putting together. Included in this dataset are daily observations derived from synoptic reports transmitted over the Global Telecommunications Systems (GTS) during the last several decades. While the synoptic reports are not as complete as one would expect daily observations to be in the countries’ archives, they do improve the availability of GSN data. The second improvement under development for GSN is a system to provide the data easily to users.

Analyses will also be presented showing the status of the networks archives. These include the beginning dates, end dates, the amount of missing data, data quality problems, the number of stations with data in the archive over the past 100 years, and how these compare with the potential data availability. The potential data available was determined from a variety of data sources (such as monthly or daily data that can’t be released) as well as sources of information about the data which were used in the initial selection of the GSN (Peterson et al., 1997). These assessments will indicate where the potential for increasing GSN availability exist and how much better it could potentially become with concerted international effort.