From Federation of Earth Science Information Partners

SWEET is a highly modular ontology suite with ~6000 concepts in ~200 separate ontologies covering Earth system science. SWEET is a mid-level ontology and consists of nine top-level concepts that can be used as a foundation for domain-specific ontologies that extend these top-level SWEET components. SWEET’s own domain-specific ontologies, which extend the upper level ontologies, can provide users interested in further developing a particular domain with a solid set of concepts to get started. SWEET ontologies are written in W3C Turtle; the Terse RDF Triple Language and are publicly available under the Apache License v2.0.

More information can be found at https://github.com/ESIPFed/sweet