The European Metrology Network (EMN) for Climate and Ocean Observation is a network of European national metrology institutes, designated institutes and affiliated partners to support the application of metrology, the science of measurement, to climate and ocean observations.

Observations from in situ sensors, networks and satellite sensors, and their transformation into bio- and geophysical quantities such as the essential climate variables (ECVs) and essential ocean variables (EOVs), are the basis of environmental information services that are used for a wide range of societal and commercial applications. Metrology enables robust, interoperable and stable observational records and aids users in judging the fitness-for-purpose of such records.