7.1 The Chairman presented to the plenary a methodology to evaluate satellite data, called a "critical review". He noted that an evaluation is important for users to estimate the usefulness of the data for specific applications, and is vital for planning operational activities and research programmes. Space agencies need the evaluation of satellite performance against user requirements to help to define future systems and to fine-tune existing systems. GOSSP, WGSAT, the CEOS Task Force and the CEOS AG have put a lot of effort into establishing a relational database, listing requirements for science areas and initiated the development of its analysis by referring to prototypes. It is essential to link requirements to specific applications, which makes it easier to specify, to validate and to update them. Furthermore, it is important to agree on standard definitions and basic terminology.
7.2 Mr Morgan introduced the concept of a requirement "range". The most demanding level is the "optimal" level, defined as the necessary level to meet requirements consistent with well documented specific applications. The least demanding level is the "threshold" level, defined as the minimal level of performance at which the system begins to add useful information to the application.
7.3 A consistent database, comprising requirement values on spatial and temporal resolutions, delivery times, random errors and bias is the essential first step. Next, it is necessary to verify satellite performances. Finally, the process compares requirements with performances for each specific application. It is intended to develop a software which will generate a colour coded summary chart. This chart will show the degree of compliance of the satellite capacities to meet the requirements and will include time-lines for relevant satellite instruments.
7.4 The process of the "critical review" will be documented in the revised Space Plan. It is proposed that the Space Plan should include summary charts of requirements and satellite capability. Other detailed information is intended to be included as supplement or may be only presented as a World Wide Web page.
7.5 In the succeeding discussion, it was stressed that the use of application areas should guarantee coherency in data requirements. Furthermore, this methodology will reveal how instrument performances will improve. It is hoped it will demonstrate how complex information on instrument performances and user estimates can be described in a clear and concise manner. Mr Morgan summarised that for the "critical review" the database is fundamental and that the required value must be correct. The challenge in establishing this process is to retain the heritage of the application requirement.
