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Geology topics

W. Johnson

Publications and source records attributed to W. Johnson.

3 recordsLinked to original sources

Priorities for IOOS ® Data Management and Communications (DMAC)

Dramatic increases in the volume of online data and rapid advances in information technology have transformed many aspects of our society. In the coastal ocean, the amount of data is also growing dramatically due to new sensor and modeling technologies. Lagging behind this deluge of ocean data, however, is an effective framework of standards, protocols, tools and culture needed to transform the way we generate knowledge and value from ocean data. The Data Management and Communications (DMAC) sub-system was envisioned to provide such an information management capability for IOOS®, promoting standards and policies to be implemented by data providers across the IOOS enterprise. DMAC needs to build upon the successes and lessons learned during development of web service standards and promote a set of end-to-end standards and procedures for the entire ocean-data life cycle, including documentation through metadata, quality control and quality assurance, effective data discovery, and stewardship through archiving. Because information technology is constantly changing, a multiyear, top-down design and implementation plan is not workable. DMAC should start by promoting a set of protocols that are functional for specific use cases, creating a modular framework in which modules can be replaced as technologies change. In addition to promoting protocols, DMAC needs to support training, flexible online documentation, support, and social networking that enable users to share code, techniques and experiences. Through this bottom-up approach, trust and understanding will foster adoption by the community. Finally, a compliance and certification process should be developed that allows IOOS to ensure that they meet the needs of customers and other stakeholders while complying with regulatory requirements related to the data. If this approach is followed, we will enable breakthroughs in ocean data–driven technology similar to those common elsewhere in our society, fulfilling the broader mission of IOOS.

Book

The sand seas of titan: Cassini RADAR observations of longitudinal dunes

The most recent Cassini RADAR images of Titan show widespread regions (up to 1500 kilometers by 200 kilometers) of near-parallel radar-dark linear features that appear to be seas of longitudinal dunes similar to those seen in the Namib desert on Earth. The Ku-band (2.17-centimeter wavelength) images show ∼100-meter ridges consistent with duneforms and reveal flow interactions with underlying hills. The distribution and orientation of the dunes support a model of fluctuating surface winds of ∼0.5 meter per second resulting from the combination of an eastward flow with a variable tidal wind. The existence of dunes also requires geological processes that create sand-sized (100- to 300-micrometer) particulates and a lack of persistent equatorial surface liquids to act as sand traps.

Science

Cassini radar views the surface of Titan

The Cassini Titan Radar Mapper imaged about 1% of Titan's surface at a resolution of ∼0.5 kilometer, and larger areas of the globe in lower resolution modes. The images reveal a complex surface, with areas of low relief and a variety of geologic features suggestive of dome-like volcanic constructs, flows, and sinuous channels. The surface appears to be young, with few impact craters. Scattering and dielectric properties are consistent with porous ice or organics. Dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons.

Science