The WMO Global Basic Observing Network: A New Approach to Improving International Exchange of Observations for Global NWP and Climate Reanalysis

Global numerical weather prediction and climate reanalysis play essential roles as the backbone for nearly all products and services provided by the WMO Members to their constituencies, even at regional and local levels. These two application areas depend on global access to consistent sets of observations provided by both surface- and space-based observing systems. WMO facilitates, coordinates and monitors the collection and international exchange of such observations. Although many of the observational requirements are partially met by satellite observations, surface-based observations continue to be essential for NWP since certain parameters can only be reliably measured from the surface at the required resolution, required frequency and/or with the required low uncertainty; for example, surface pressure, precipitation, snow depth, and detailed near-surface vertical profiles. Surface observations are also important for characterising biases in satellite observations.

Current monitoring statistics generated by the WIGOS Data Quality Monitoring System are showing continued poor, or even declining, coverage and availability of surface-based observational data over many areas of the global domain. The current Global Observing System is composed of six Regional Basic Synoptic Networks that are implemented and managed by the individual Members, largely in response to local and regional requirements. This approach has led to inconsistencies in the implementation, with the individual regional networks having vastly different performance characteristics, and it has left large areas void of surface observations. Both of these shortcomings have a significant adverse impact on NWP and climate reanalysis, thus limiting the ability of all WMO Members to provide weather and climate services to their constituencies.