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Lugo-Fernandez A.,Ocean energy | Leben R.R.,University of Colorado at Boulder
Journal of Physical Oceanography | Year: 2010

A linear correlation exists between the retreat latitude of the Loop Current following eddy separation and the subsequent eddy separation period. This empirical relationship was first identified in satellite altimeter-derived Loop Current metrics. In this paper, a simple vorticity model of the Loop Current is used to provide a semitheoretical basis for this relationship. After suitable scaling approximations, the theory predicts that the LC separation period is a linear function of retreat latitude, which agrees well with altimeter-derived empirical results. Specifically, the predicted slope and y intercept agree to within 9% and 2%, respectively, with the altimetry-derived values. © 2010 American Meteorological Society. Source


Roberts H.H.,Louisiana State University | Shedd W.,Ocean energy | Hunt J.,Retired
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2010

Use of DSV ALVIN (2006) and ROV JASON II (2007) provided access to never observed or sampled sites of fluid-gas expulsion from the little-studied middle and lower continental slope of the northern Gulf of Mexico (below water depths of 1000. m). Dives were focused on 15 locations selected by 3-D seismic surface attributes and shallow subsurface geologic analyses. The linkage between highly positive seafloor reflectivity and hard bottoms proved to be an efficient indicator of potential sites of interest. Through observation and sampling of reflective sites, starting in the mid-1980s, it has become apparent that most hard bottoms on the northern Gulf's continental slope are created by the precipitation of authigenic carbonates at hydrocarbon seep sites. Access to the Bureau of Ocean Energy Management, Regulation and Enforcement's extraordinary archive of slope-wide 3-D seismic data made efficient site selection possible. From thousands of sites that display the characteristics of fluid-gas expulsion, 15 were observed and sampled during the 2006 and 2007 cruises. Water depths in which these 15 sites were located ranged from ~2750 to ~970 m. All sites exhibited evidence of hydrocarbon seepage or more rapid venting. Chemosynthetic organisms, authigenic carbonates, barite, gas hydrates, highly anoxic surface sediments, brine pools, and hydrocarbon-laced brine flows were identified and sampled. High-resolution acoustic Autonomous Underwater Vehicle (AUV) data, including multibeam bathymetry, side-scan sonar swaths, and chirp sonar subbottom profiles, were collected at four locations (AC601, WR269, GC852, and AT340). Data sets from the 2006 and 2007 dives resulted in a greatly improved understanding of both cross-slope and along-slope variability in the characteristics of fluid-gas expulsion sites and associated habitats. Our studies confirmed the importance of fluid-gas expulsion processes for sustaining chemosynthetic communities and impacting seabed geology on the middle and lower continental slope of the northern Gulf of Mexico. © 2010 Elsevier Ltd. Source


Bromirski P.D.,University of California at San Diego | Miller A.J.,University of California at San Diego | Flick R.E.,University of California at San Diego | Auad G.,University of California at San Diego | Auad G.,Ocean energy
Journal of Geophysical Research: Oceans | Year: 2011

Long-term changes in global mean sea level (MSL) rise have important practical implications for shoreline and beach erosion, coastal wetlands inundation, storm surge flooding, and coastal development. Altimetry since 1993 indicates that global MSL rise has increased about 50% above the 20th century rise rate, from 2 to 3 mm yr-1. At the same time, both tide gauge measurements and altimetry indicate virtually no increase along the Pacific coast of North America during the satellite epoch. Here we show that the dynamical steric response of North Pacific eastern boundary ocean circulation to a dramatic change in wind stress curl, Txy, which occurred after the mid-1970s regime shift, can account for the suppression of regional sea level rise along this coast since 1980. Alarmingly, mean Txy over the North Pacific recently reached levels not observed since before the mid-1970s regime shift. This change in wind stress patterns may be foreshadowing a Pacific Decadal Oscillation regime shift, causing an associated persistent change in basin-scale Txy that may result in a concomitant resumption of sea level rise along the U.S. West Coast to global or even higher rates. © 2011 by the American Geophysical Union. Source


Vandegraft D.L.,Ocean energy
Cartography and Geographic Information Science | Year: 2015

Federal government mapping of the offshore areas of the USA in support of the development of oil and gas resources began in 1954. The first mapping system utilized a network of rectangular blocks defined by State Plane coordinates which was later revised to utilize the Universal Transverse Mercator grid. Creation of marine boundaries directed by the Submerged Lands Act and Outer Continental Shelf Lands Act were mathematically determined using early computer programs that performed the necessary computations, but required many steps. The Bureau of Ocean Energy Management is revising these antiquated methods using Geographic Information System technology which will provide the required accuracy and produce the mapping products needed for leasing of energy resources, including renewable energy projects, on the outer continental shelf. Source


Claisse J.T.,Occidental College | Pondella D.J.,Occidental College | Love M.,University of California at Santa Barbara | Zahn L.A.,Occidental College | And 3 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

Secondary (i.e., heterotrophic or animal) production is a main pathway of energy flow through an ecosystem as it makes energy available to consumers, including humans. Its estimation can play a valuable role in the examination of linkages between ecosystem functions and services. We found that oil and gas platforms off the coast of California have the highest secondary fish production per unit area of seafloor of any marine habitat that has been studied, about an order of magnitude higher than fish communities from other marine ecosystems. Most previous estimates have come from estuarine environments, generally regarded as one of the most productive ecosystems globally. High rates of fish production on these platformsultimately result fromhigh levels of recruitment and the subsequent growth of primarily rockfish (genus Sebastes) larvae and pelagic juveniles to the substantial amount of complex hardscape habitat created by the platform structure distributed throughout the water column. The platforms have a high ratio of structural surface area to seafloor surface area, resulting in large amounts of habitat for juvenile and adult demersal fishes over a relatively small footprint of seafloor. Understanding the biological implications of these structures will inform policy related to the decommissioning of existing (e.g., oil and gas platforms) and implementation of emerging (e.g., wind, marine hydrokinetic) energy technologies. © 2014, National Academy of Sciences. All rights reserved. Source

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