User requirements for observation (OSCAR/Requirements)

This database is the official repository of requirements for observation of physical variables in support of WMO Programmes and Co-sponsored Programmes. These requirements are maintained by the focal points designated for each application area.
It is the foundation of the Rolling Requirements Review (RRR) process overviewed by the Inter-Programme Expert Team on Observing System Design and Evolution (IPET-OSDE) of CBS. (More information)

The requirements are regularly reviewed by groups of experts nominated by these organizations and programmes. For WMO, this process is conducted by the Inter-Programme Expert Team on Observing System Design and Evolution (IPET-OSDE) and its designated focal points for each of the Application areas .

In addition, Themes offer an additional, cross-cutting view on variables and requirements

Using the database

To explore the database, you can use the "Quick Search" in the top right corner, when looking for a specific Variable or Application area. You can also consult the full tables accessible through the top menu, and use the filter options provided.

The database is open for consultation. Editing is only possible by designated focal points, after login.

For any questions or clarifications regarding the content of the database , please directly contact the respective focal point. A list of all focal points can be found on the Application areas page


Requirements are expressed for geophysical variables in terms of 6 criteria: uncertainty, horizontal resolution, vertical resolution, observing cycle, timeliness, and stability (where appropriate).
For each of these criteria the table indicates 3 values determined by experts:

  • The "threshold" is the minimum requirement to be met to ensure that data are useful
  • The "goal" is an ideal requirement above which further improvements are not necessary
  • The "breakthrough" is an intermediate level between "threshold" and "goal" which, if achieved, would result in a significant improvement for the targeted application. The breakthrough level may be considered as an optimum, from a cost-benefit point of view, when planning or designing observing systems.

The "uncertainty" characterizes the estimated range of observation errors on the given variable, with a 68% confidence interval (1 σ ).