This document describes the concept being developed by the Global Geodetic Observing System (GGOS) for the definition of Essential Geodetic Variables (EGVs). Following the same arrangement of the Global Climate Observing System (GCOS) and the Global Ocean Observing System (GOOS) for the definition of the Essential Climate Variables (ECVs) and the Essential Ocean Variables (EOVs), respectively, we present a catalogue of 18 EGVs based on 54 geodetic products. The first step in this process is to build consensus within the international geodetic community on this catalogue and then to define the requirements for the geodetic products supporting the EGVs. This effort will also include the identification of responsible stewards for each EGV. Community involvement is being facilitated through review by or consultation with the GGOS Science Panel, the GGOS Governing Board, the IAG Executive Committee and the key IAG components (Services, Commissions, Inter-Commission Committees, Projects). Following their feedback, a wider public review will be initiated, taking into account relevant stakeholders and the global geodetic community, to balance collective interests and secure international and interdisciplinary recognition.
Gruber et al. (Tue,) studied this question.