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Providing access to observational climate data and its metadata has been important for climatology. Historically, climate data has been made available by some national data platforms or through the European Climate Assessment and Database (ECAD). Users often had to pay for data access and output was provided in different formats. The newly in force EU open Data Directive 2019/1024 requires National Meteorological and Hydrological Services (NMHSs) to make their High Value Datasets, including meteorological datasets, available through machine readable application programming interfaces (APIs). RODEO work package 5 (WP5) aims to unite ten NMHSs that are developing APIs for their climate databases. Afterwards, an API aggregator service unifies the individual APIs, so that the clients can use all APIs with only one request. In this presentation we will report on progress made in RODEO WP5. WP5 worked on uniforming climate datasets, including its metadata. A group of experts decided on the choice of variable to include, granularity of daily and hourly observations, and preferred controlled vocabularies. Metadata guidance from WMO, Copernicus and ESIP are incorporated to adhere to the FAIR principles. The API recommendations for NMHS data providers will follow the Environmental Data Retrieval (EDR) API specification. Using an EDR API it is possible to perform geospatial and temporal filterable queries of climate data. The EDR specification, published by Open Geospatial Consortium (OGC) in 2016, has, over recent years, gained traction as an ideal method to distribute meteorological data over the internet. The OGC has adopted CoverageJSON asdata format standard alongside the EDR API. This format will be the preferred output format for an NMHS climate data API. The EDR aggregator service will facilitate the unification of individual NMHS APIs to one central EDR API. The aggregator service can add caching, output format conversion from CoverageJSON to NetCDF or CSV and support queries across collections. To aid in the development of NMHS climate data EDR APIs, a workshop Build an EDR API in a day is being prepared to run in June 2024. A spin-off of this event is being planned in Spring 2025 for non-RODEO partners.
Schayck et al. (Fri,) studied this question.