The Ontology-based Metadata Portal for Unified Semantics (OlyMPUS) will extend the prototype Ontology-Driven Interactive Search Environment for Earth Sciences (ODISEES) developed at NASA's Atmospheric Science Data Center (ASDC) to enable users to find and download data variables that satisfy their precise criteria. The ODISEES-OlyMPUS end-to-end system will support both data consumers and data providers, enabling the latter to register their data sets and provision them with the semantically rich metadata that drives ODISEES' data discovery and access service for data consumers. A core function of NASA's Earth Science Division is research and analysis that uses the full spectrum of data products available in NASA archives. Scientists need to perform comprehensive analyses that identify correlations and non-obvious relationships across all types of Earth System phenomena. Comprehensive analytics are hindered, however, by the fact that many data products and climate model products are disparate and hard to synthesize. Variations in how data are collected, processed, averaged, gridded, and stored, create challenges for data interoperability and synthesis, which are exacerbated by the sheer volume of available data. A coordinated approach to data delivery will greatly improve prospects for interoperability and synthesis, better enabling scientists to take advantage of the full range of global data from satellites and aircraft, as well as outputs from numerical models. Metadata has emerged as a means of improving data delivery and interoperability. Robust, semantically rich metadata can support tools for data discovery and access and facilitate machine-to-machine transactions with services such as data subsetting, regridding, and reformatting. Such capabilities are critical to enabling the research activities integral to NASA's strategic plans. However, as metadata requirements increase and competing standards emerge, data producers are increasingly burdened with the time-consuming task of provisioning their data products. Adequate tools for metadata provisioning are not commonplace. Although some metadata provisioning tools are available, the metadata they produce typically has little or no semantic framework, is generally coarse-grained, and is frequently inadequate to provide the sort of information required to support data interoperability. If metadata is to provide the means to address interoperability challenges, then tools that support the needs of both data consumers and data providers have to be developed. The OlyMPUS project will: 1. Expand the capabilities of ODISEES to improve existing search capabilities and introduce new features and capabilities, raising the Technology Readiness Level from 3 to 5 over the two-year effort. 2. Leverage the robust semantics and reasoning capabilities of ODISEES to provide data producers with a semi-automated tool - the OlyMPUS Metadata Provisioning System - to produce the robust and detailed semantic metadata needed to support ODISEES' parameter-level discovery and access services. 3. Integrate ODISEES with select data delivery tools at the ASDC and National Center for Climate Simulation (NCCS) to enable data consumers to create customized data sets and download them directly to their computers or, for registered users of the NASA Advanced Supercomputing (NAS) facility, directly to NAS storage resources for access by applications running on NAS supercomputers.