User Requirement Definition (URD)
User Requirement Definition (URD) document outlines the user requirements regarding mesospheric observations of targets such as temperature, ozone, water vapour, methane, nitrogen oxides, metallic species, and polar mesospheric clouds.
The user requirements are defined from the point of view of climate modellers based on science needs independent of constraints such as spatial resolution, accuracy and observation frequency established by existing observational data sets. In this sense, the URD reflects what is needed in terms of observational data to achieve certain science goals, e.g. validation of long-term trends in climate models by observation. The scientific rationale behind the selection of the requirements is given as appropriate throughout the document. In some cases these requirements match the constraints of existing data, while most often constraints are exceeded. This discrepancy can be interpreted as demand for new observation capabilities, and specifications for future satellite missions can be derived from the requirements.
Download the URD document, version 2.2.