Measurements of bubble plumes and turbulence from a submarine     

T. Osborn  D.M. Farmer  S. Vagle  S.A. Thorpe  M. Cure 《大气与海洋》2013,51(3):419-440

Abstract

An experiment using turbulence probes and an array of side‐scan and vertically pointing pencil beam sonars mounted on the U.S. submarine Dolphin was carried out to measure turbulence in near‐surface regions of acoustic scattering, in particular, those caused by subsurface bubbles produced by breaking wind waves. The dataset collected during winds of 5–9 m s^?1 reveals the banded patterns of bubbles associated with Langmuir circulation, even though no surface manifestations were visible.

A forward‐pointing side‐scan sonar determined the “age” of bubble clouds after their generation by breaking waves. There is enhanced turbulent dissipation in the bubble clouds, and the dissipation rate close to the surface exceeds that predicted using conventional calculations based on the law of the wall and buoyancy flux. The correspondence between bubbles and turbulence implies a horizontally patchy turbulent structure near the surface. Below the base of the bubble clouds the distance between turbulent patches increases and is much greater than that of the bubble clouds. The submarine provides an excellent platform for multi‐sonar near‐surface studies.  相似文献   

The Sensitivity of Four Monitoring Well Sampling Systems to Low Concentrations of Three Volatile Organics     

Ronald Schalla  David A. Myers  Mary Ann Simmons  John M. Thomas  Antony P. Toste 《Ground Water Monitoring & Remediation》1988,8(3):90-96

Four state-of-the-art ground water sampling systems were analyzed to determine their reliability in providing representative samples of the volatile chlorinated hydrocarbons trichloroethylene (TCE), perchloroethylene (PCE), and 1,1,1-trichloroethane (TCA) from a simulated monitoring well. The sampling systems studied represent four commonly used devices, including a stainless steel and Teflon® piston pump, a Teflon bailer, a Teflon bladder pump, and a PVC air-lift pump.
Controlled laboratory sampling experiments were conducted in a tank and well test chamber designed to approximate field conditions. A well purging and sampling procedure was used in the test apparatus to determine the accuracy and precision of each device for detecting low concentrations of the compounds in ground water. The compounds selected are some of the most ubiquitous hazardous contaminants found in shallow aquifers near hazardous waste sites throughout the United States.
No significant statistical difference was found among the four sampling systems in detecting the compounds.  相似文献   

Rotational deformation during Palaeogene thrusting and basin closure in eastern central Greece: palaeomagnetic evidence from Mesozoic carbonates   总被引：1，自引：0，他引：1  

Antony Morris 《Geophysical Journal International》1995,121(3):827-847

  相似文献   

The Continental Slope Experiment along the Tasman Project profile, southeast Australia     

Antony White 《Physics of the Earth and Planetary Interiors》1990,60(1-4):147-154

Three seafloor magnetometers made recordings for up to 95 days between July and October 1986 at site across the continental slope of southeast Australia along the profile of the 1984 Tasman Project of Seafloor Magnetotelluric Exploration (TPSME). Land magnetometers at TPSME sites at the coast and Canberra were reactivated to give simultaneous recordings. The seafloor magnetometers were at depths of 140 m, 2240 m and 3380 m and spanned the continental shelf between the coastline and the closest inshore TPSME ocean floor site (depth 4850 m). This experiment complements the TPSME by giving a much sharper definition of the geomagnetic coast effect in this critical region.

Data are presented in the form of Parkinson arrows for comparison with previously derived TPSME results along the profile. They show a strong coast effect with the maximum mid-way down the continental slope. The situation is closely two dimensional, and using this approximation some simple models have been computed. One which gives a relatively good fit at a period of 1 h comprises simply a conductive ocean overlying a uniform conductor at depth. Further work will be needed to determine whether lateral conductivity structure at depth is required to fit the data more closely.  相似文献   

Wastes in the ocean,vol. 3, radioactive wastes and the ocean: P. Kilho Park,Dana R. Kester,Iver W. Duedall and Bostwick H. Ketchum (eds.). John Wiley and Sons,New York, 1983. 522 pp. Price £69.95     

S.A. Thorpe 《Marine pollution bulletin》1985,16(5):214

  相似文献   

Petrogenesis of calc-alkaline,shoshonitic and associated ultrapotassic Oligocene volcanic rocks from the Northwestern Alps,Italy   总被引：1，自引：0，他引：1  

G. Venturelli  R. S. Thorpe  G. V. Dal Piaz  A. Del Moro  P. J. Potts 《Contributions to Mineralogy and Petrology》1984,86(3):209-220

Along the Western Alps there is geological evidence of late-Alpine (Oligocene) magmatic activity which clearly postdates the Lepontine (Eocene-early Oligocene) metamorphism and related deformation of the Alpine nappe pile. This magmatic activity was notably delayed in relation to the most important convergent processes and may be related to buoyancy of lithosphere, tensional tectonics and thermal updoming subsequent to the collision between the Eurasian and African plates. The geochemical features of the rocks and the geophysical characteristics of the Alpine chain, suggest that: (a) shoshonitic and calcalkaline melts may have been generated by partial melting of metasomatized peridotitic material and subsequent fractional crystallization and crustal contamination; silicic andesites and latites, however, could have been also derived from metasomatized eclogite or deep continental crust material; (b) the ultrapotassic lamprophyres with high K, P, LREE, Th, Zr, U and high ⁸⁷Sr/⁸⁶Sr ratios were generated by partial melting of strongly metasomatized mantle; the varied Sr-isotopic ratios may partially also reflect additional radiogenic component from the continental crust following magma segregation from the source.  相似文献   

The characteristics of breaking waves, bubble clouds, and near-surface currents observed using side-scan sonar     

S.A. Thorpe  A.J. Hall 《Continental Shelf Research》1983,1(4):353-384

An inverted 248 kHz two-component side-scan sonar mounted on the sea bed in a mean depth of 34 m has been used to detect the clouds of bubbles produced by breaking surface waves. The sonar has a range of about 150 m. The breaking waves appear on the sonograph records as short-lived intense echoes, and form patterns which can be explained in terms of the behaviour of groups of waves in which the highest are breaking.The bubble clouds are slightly elongated in the wave direction when they are first formed and, in winds of 5.1 m s⁻¹, have lifetimes of up to about 5 min. Soon after a wave breaks, the horizontal motion of the fluid in which the bubbles are formed becomes similar to that of the surroundings, and the bubbles continue to be advected by the near-surface currents. The rate of drift of bubble clouds along the directions of the sonar beams allows the components of the currents to be measured.The sonographs show that large changes in currents can occur over horizontal distances of as little as 5 to 10 m when fronts are passing. The motion of the fronts through the water can be measured. The sonographs have been used to measure surface currents induced by internal waves. Bands of bubbles associated with Langmuir circulation can be detected in strong winds or when moderate winds are accompanied by heavy rain.  相似文献   

The 1980 eruptions of Mount St. Helens, Washington: P.W. Lipman and D.R. Mullineaux (editors), United States geological survey, professional paper 1250. United States Geological Survey, Reston, VA, 1982, xxvii + 844 pp., US $35.00 (hardcover)     

R.S. Thorpe 《Tectonophysics》1983,96(1-2)

  相似文献   

Change in the magnetic properties of bituminous coal intruded by an igneous dike, Dutch Creek Mine, Pitkin County, Colorado   总被引：1，自引：0，他引：1  

A. N. Thorpe  F. E. Senftle  R. B. Finkelman  F. T. Dulong  N. H. Bostick 《International Journal of Coal Geology》1998,36(3-4)

Magnetization measurements have been made on natural coke–coal samples collected at various distances from a felsic porphyry dike in a coal seam in Dutch Creek Mine, Colorado to help characterize the nature and distribution of the iron-bearing phases. The magnetization passes through a maximum at the coke-to-coal transition about 31 cm from the dike contact. The magnetic measurements support the geochemical data indicating that magmatic fluids along with a high-temperature gas pulse moved into the coal bed. Interaction of the magmatic fluids with the coal diminished the reducing power of the thermal gas pulse from the dike to a point about 24 cm into the coal. The hot reducing gas penetrated further and produced a high temperature (400–525°C) zone (at about 31 cm) just ahead of the magmatic fluids. Metallic iron found in this zone is the principal cause of the observed high magnetization. Beyond this zone, the temperature was too low to alter the coal significantly.  相似文献   

The Néel transition and magnetic properties of terrestrial,synthetic, and lunar ilmenites     

Frank E. Senftle  Arthur N. Thorpe  Charles Briggs  Corrine Alexander  Jean Minkin  David L. Griscom 《Earth and Planetary Science Letters》1975,26(3):377-386

The magnetic susceptibility of a terrestrial, synthetic and lunar ilmenite specimen has been measured from 4 to 300 K. All specimens had a single Néel temperature transition which ranged from 56 to 57.7 K. In one case the powdered specimen was partially aligned in the magnetic field prior to the susceptibility measurements and the Néel transition was observed to shift to 60 K indicating magnetic anisotropy. A study of several magnetic parameters calculated from the experimental data showed gross impurities in the terrestrial specimen, single-domain to multi-domain metallic iron in the synthetic specimen, and a small amount of superparamagnetic metallic iron in the lunar sample. No multidomain iron was observed in the lunar ilmenite. The results of electron spin resonance measurements were also in general agreement with these findings. Because of the absence of Fe³⁺ compared to most terrestrial samples it is suggested that the anisotropic magnetic parameters be determined on lunar ilmenite when a large enough single crystal becomes available.  相似文献