Designing and implementing a data model for describing environmental monitoring and research sites

With new technological advancements and increasing demands of open data in environmental sciences, the requirements for data are increasing in a variety of ways. Having machine and human readable documentation about environmental research and monitoring sites available online is one of them. The Dynamic Ecological Information Management System - Site and Dataset Registry (DEIMS-SDR, https://www.deims.org/) is a research and monitoring site registry that allows the description of in-situ observation or experimental sites, generating persistent, unique and resolvable identifiers for each site. The aim of DEIMS-SDR is to collect site information in a catalogue describing a wide range of sites across the globe, providing information including each site's location, ecosystems, facilities, measured parameters and research themes and enabling that standardised information to be openly available. This article describes the outcomes of the revision of its data model, the conceptual considerations behind it and how it is implemented. These conceptual considerations also encompass the definition of what we call the "onion model of site data interoperability" - a fundamental concept for the design of site data models against the backdrop of data interoperability. Furthermore, we illustrate the capabilities of the revised data model and provide an overview of common data formats for the description of sites, current initiatives driving the harmonisation of descriptions and the outlook of future developments.