Side-scan and acoustic subbottom characterization of the sea floor near the Dry Tortugas, Florida     

Thomas F. Wever  Hannelore M. Fiedler  Gunther Fechner  Friedrich Abegg  Ingo H. Stender 《Geo-Marine Letters》1997,17(4):246-252

 Between 2 and 6 February, 1995, a 25 km² area at the Dry Tortugas (Florida Keys) was surveyed with a 100 kHz side-scan sonar system and 3.5-kHz subbottom profiler. The side-scan system revealed a pattern of alternating high and low backscatter. The subbottom profiler showed areas with no acoustic penetration between sediment troughs. The combination of both methods allowed delineation of the boundaries in high-backscatter regions, and sediment samples allowed correlations between high backscatter and coarser-grained sediments.  相似文献   

Cross-shelf exchange in a model of the Ross Sea circulation and biogeochemistry   总被引：1，自引：0，他引：1  

Michael S. Dinniman  John M. Klinck  Walker O. Smith  Jr. 《Deep Sea Research Part II: Topical Studies in Oceanography》2003,50(22-26):3103

Transport of warm, nutrient-rich Circumpolar Deep Water (CDW) onto Antarctic continental shelves and coastal seas has important effects on physical and biological processes. The present study investigates the locations of this transport and its dynamics in the Ross Sea with a high-resolution three-dimensional numerical model. The model circulation is forced by daily wind stress along with heat and salt fluxes calculated from atmospheric climatologies by bulk formulae. All surface fluxes are modified by an imposed climatological ice cover. Waters under the Ross Ice Shelf are not included explicitly, but their effect on temperature and salinity is imposed in a buffer zone at the southern end of the model domain. A simple nutrient uptake is calculated based on the climatological chlorophyll distribution and Monod uptake kinetics.Model circulation is strongly affected by bottom topography, due to weak stratification, and agrees with schematics of the general flow and long-term current measurements except near the southern boundary. The sea-surface temperature is similar to satellite estimates except that the warmest simulated temperatures are slightly higher than observations. There is a significant correlation between the curvature of the shelf break and the transport across the shelf break. A momentum term balance shows that momentum advection helps to force flow across the shelf break in specific locations due to the curvature of the bathymetry (that is, the isobaths curve in front of the flow). For the model to create a strong intrusion of CDW onto the shelf, it appears two mechanisms are necessary. First, CDW is driven onto the shelf at least partially due to momentum advection and the curvature of the shelf break; then, the general circulation on the shelf takes the CDW into the interior.  相似文献   

Provenance and dispersal of muds south of the Aleutian arc,north Pacific Ocean     

Michael B. Underwood  Eric G. Hathon 《Geo-Marine Letters》1989,9(2):67-75

X-ray diffraction analyses show that the clay mineralogies of near-surface muds in the Gulf of Alaska (mostly illite and chlorite) are consistent with detrital sources in southern Alaska. Expandable clay minerals are derived from the Aleutian volcanic arc, and their percentages increase progressively toward the west. Smectite values are lower than expected, however, particularly in the central forearc, and there is less smectite on the insular trench slope than farther seaward. The regional clay-mineral distribution is controlled by two opposed contour currents and by the influx of suspended sediment via both transverse and trench-axis turbidity currents.  相似文献   

A simple meteorological buoy with satellite telemetry     

Michael Reynolds 《Ocean Engineering》1983,10(1):65-76

A small, inexpensive, and easily deployable meteorological buoy is described. Buoy motion is greatly reduced by appropriate ballast techniques; vector averaging further removes buoy motion effects from wind data. Data is transmitted to the GOES satellite and is retrieved by telephone. Measurements are vector-averaged wind components, wind speed, wind direction, water temperature, air temperature, and compass direction. Data from two field trials are discussed. Speed comparisons averaged 0.2 m sec⁻¹ with a standard deviation of 0.6 m sec⁻¹. Direction comparisons were different due to local topography, but they indicate a probable accuracy of ±5°.  相似文献   

Barotropic tidal mixing effects in a coupled climate model: Oceanic conditions in the Northern Atlantic   总被引：3，自引：0，他引：3  

Hyun-Chul Lee  Anthony Rosati  Michael J. Spelman 《Ocean Modelling》2006,11(3-4):464-477

Impacts of mixing driven by barotropic tides in a coupled climate model are investigated by using an atmosphere–ocean–ice–land coupled climate model, the GFDL CM2.0. We focus on oceanic conditions of the Northern Atlantic. Barotropic tidal mixing effects increase the surface salinity and density in the Northern Atlantic and decrease the RMS error of the model surface salinity and temperature fields related to the observational data.  相似文献   

Microzooplankton production in the oceans   总被引：7，自引：0，他引：7  

Landry  Michael R.; Calbet  Albert 《ICES Journal of Marine Science》2004,61(4):501-507

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Trophodynamic control on recruitment success in Baltic cod: the influence of cannibalism   总被引：1，自引：1，他引：1  

Neuenfeldt  Stefan; Koster  Friedrich W. 《ICES Journal of Marine Science》2000,57(2):300-309

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Sonographs of submarine sediment failure caused by the 1980 earthquake off northern California     

Michael E. Field  Robert K. Hall 《Geo-Marine Letters》1982,2(3-4):135-141

In 1980, a large earthquake caused extensive sediment failure on the shallow continental shelf off the Klamath River in northern California. Side-scan sonography was used to complement detailed geophysical profiling in identifying specific features and resolving modes of failure. The features include a nearly flat failure terrace mantled with sand boils, collapse craters and sediment flows, and bounded on the seaward side by a meandering continuous toe ridge. Seaward of the terrace lies a compression zone delineated by small pressure ridges. Our findings indicate a temporal progression of failure from lique-faction of shallow subsurface sand to lateral spread of intact blocks to sediment collapse and flow.  相似文献   

Storm-built sand ridges on the Maryland inner shelf: a preliminary report     

Donald J. P. Swift  Michael E. Field 《Geo-Marine Letters》1981,1(1):33-37

Several aspects of the Maryland ridge field are pertinent to the problem of ridge genesis in response to Holocene sea-level rise. There is a systematic morphologic change fromshoreface ridges throughnearshore ridges tooffshore ridges, which reflects the changing hydraulic regime. Grain size is 90° out of phase with topography, so that the coarsest sand lies between the axis of each trough and the adjacent seaward ridge crest, while the finest sand lies between each ridge crest and the axis of the adjacent seaward trough. Finally, analysis over a 43-year period on an outer ridge reveals a systematic pattern of landward flank erosion, seaward flank deposition, and seaward crest migration. These relationships support a model which explains the ridges as consequences of the up-current shift of maximum bottom shear stress with respect to the crests of initial bottom irregularities. The oblique orientation of the ridges with respect to the beach may be at least partly due to the more rapid migration rate of the ridges’ inshore ends.  相似文献   

Baltic cod recruitment - the impact of climate variability on key processes   总被引：3，自引：0，他引：3  

Koster  Friedrich W.; Mollmann  Christian; Hinrichsen  Hans-Harald; Wieland  Kai; Tomkiewicz  Jonna; Kraus  Gerd; Voss  Rudiger; Makarchouk  Andrei; MacKenzie  Brian R.; St. John  Michael A.; Schnack  Dietrich; Rohlf  Norbert; Linkowski  Tomasz; Beyer  Jan E. 《ICES Journal of Marine Science》2005,62(7):1408-1425

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