Deep Sea Research and Oceanographic Abstracts最新文献

Of the many current measurements made by the Woods Hole Oceanographic Institution, one set, made at Site D, 39°N, 70°W, in the fall of 1969, has a double peak in its energy spectrum, one on each side of the local inertial frequency. Coincident with these current records were expendable bathythermograph and infra-red aircraft observations indicating the presence of an anticyclonic eddy that drifted through the observing site. The observed split in the inertial peak of the current records is attributed to variations in the effective inertial frequency caused by the vertical component of vorticity associated with the eddy.

The vertical distribution of respiratory electron transport system (ETS) activity has been determined through the oxygen-deficient zone of the eastern tropical North Pacific. Adenosine triphosphate (ATP) concentration has also determined in the Costa Rica Dome area. There is a distinct, local ETS activity maximum associated with the oxygen minimum but no corresponding ATP increase. It is suggested that the ETS activity maximum results from intracellular biochemical modifications of the ETS system in response to the stress imposed by the low oxygen concentrations, because it is not associated with an increase in ATP biomass. These distributions are also discussed in light of recent suggestions of a mid-depth bacterioplankton maximum.

A vertical array of four equidistant current meters was used to measure horizontal currents in 18 m of water. The instruments resolved frequencies up to 15 cph for a period of 33 days in late summer 1974. Onshore (EW) and longshore (NS) currents were essentially uncorrelated at all depths. Longshore currents exhibit significant coherence with the surface tide but not at frequencies higher than the tidal frequencies. The effect of a southerly wind lasting over 3 days was evident as a northbound current that was most intense near the surface. The spectrum of onshore currents exhibits a peak at the semidiurnal frequency corresponding to internal tides, and there is a second lower, but broader, peak at frequencies between 1 cph and the buoyancy frequency. Onshore current amplitudes corresponding to the internal tides are on the order of 20 cm s⁻¹, while the higher frequency fluctuations have amplitudes on the order of 3 cm s⁻¹. There is significant coherence between all measurements of onshore current with a phase shift of π between surface and bottom currents. The onshore current measurements are consistent with the mode 1 oscillations of a three-layer model consisting of homogeneous surface and bottom layers separated by a layer having constant buoyancy frequency.

A method is described for determining pressure-volume isotherms of liquids at high pressures. A volumometer without a ground glass joint is used. The pressure-volume-temperature (PVT) surface of Isopar-M has been determined, and shows that this hydrocarbon liquid is suitable for floats to 1100 bars at 0°C. The so-called Tait equation has been used as the equation of state for the PVT values.

A high carbonate ooze core of Lower Pleistocene age from the Discovery Tablemount contains planktonic foraminifera, coccoliths, ice-rafted detritus and little clay. Thin-shelled planktonic foraminifera indicate a shoaling to 200 m during the Lower Pleistocene. Changes in the foraminiferal population indicate two cold episodes during which the Antarctic Convergence was considerably further north than at present. An abundance of ice-rafted quartz sand grains coincides with the latter part of a warm period; the grains are ice and wind erosion products of exposed Antarctic rocks. Dredged volcanic rocks indicate volcanism occurred on the tablemount at 25 m.y. BP (K/Ar) and 6.5 to 7 m.y. BP(induration of ooze).

The spectra of either temperature, salinity or vertical velocity which might be measured by a sensor moving through a field of salt fingers are considered. A theoretical calculation is presented which attempts to incorporate the deviations from squareness and perfect orientation of the salt fingers. The resulting spectra rise to a peak close to ω = (√2)kv and decrease rapidly for larger ω, where ω is the temporal frequency of the spectrum, k the dominant wave number of the salt fingers and ν the horizontal velocity of the sensor. A spectrum of vertical velocity of laboratory-generated salt fingers is shown to be in close agreement with the theoretical prediction.