ALBERT

Beschreibung: The second half of CHAIN Cruise #11, 22 February until 22 March, 1960, is detailed as to type of measurements made with their specific locations. The cruise areas were in the St. Croix region, the Puerto' Rico Trench and the tracks from the Bahamas to Bermuda to Woods Hole. Camera lowerings, lowerings of the thermal probe and accompanying cores, dredging, sound velocimeter lowerings, and acoustic studies of the scattering layer were the special events undertaken while precision bathymetry and towing of the Continuous Temperature Recording Chain were on a watch standing basis.

Beschreibung: Undersea Warfare Branch, Office of Naval Research Under Contract Nonr- 1367(00) (NR- 261-10 2)

Beschreibung: The objective of this investigation was to measure bottom loss in normal incident reflection of pulses of twelve kcps sound and to study its geological significance. To this end a semi-automatic instrument system was developed which is capable of making continuous measurements of the peak pressure and the time integral of the square of the pressure of the sea floor echo, from a vessel underway. Observations were taken in both deep and shallow water areas in the Western North Atlantic. The early cruises were conducted in deep water to investigate the range and variability of bottom loss values. Geological control consisted mainly of a precise bathymetric record. The later cruises were conducted in shall ow water, in areas where the geology has been well studied previously by investigators using techniques of classical geology. In these latter cruises the acoustic measurements were correlated with a schedule of sediment dredging and underwater photography. Thirty-one thousand acoustic measurements were made. Median bottom loss values and standard deviations were computed and the results summarized in eleven hundred sets, each set corresponding to a location at sea. Seventy-seven sediment stations were occupied. A complete particle size analysis and a water content analysis were performed on these sediments to determine their size and mass characteristics . The size characteristics included the median grain size, the sorting coefficient, and the percentages of gravel, sand, silt, and clay. A sediment class name was determined from the gravel, sand, silt, and clay percentages according to the Shepard system of classification. The mass characteristics included porosity, bulk density, sound velocity, acoustic impedance, Rayleigh reflection coefficient, and theoretical bottom loss. The combined results show a good correlation between measurements of bottom loss and both mass and size characteristics of the sediment. The measured bottom loss increases as the porosity increases. The measured bottom loss also increases as the silt-clay percentage increases since the porosity of sediments generally increases as this fraction increases. It seems that the Rayleigh reflection coefficient can be used to predict acoustic bottom loss at normal incidence. Conversely, normally-incident bottom loss can be used under the assumption of a Rayleigh reflection process to determine the nature of the bottom sediment. The acoustical and geological results have been made available in tabulations, scatter diagrams, and as geographical plots. Except for the initial measurements, all operations, including the final displays, were accomplished through automatic digital processing machines.

Beschreibung: The Office of Naval Research under Contract Nonr-4029 ~ Nonr-13 67~ Nonr-1841 (74) ~ NR 083 -15 7~ and the Bureau of Ships under Contracts NObsr-72521 and NObsr-89464.

Beschreibung: The theory of oblique-angle seismic reflectivity, as applied to oceanographic research, is presented. An experiment has been developed in which continuous oblique reflection profiles were made by towing an acoustic source behind a ship and listening with a hydrophone suspended beneath a free-floating radio buoy. Information received at the hydrophone was transmitted to the ship and recorded on magnetic tape. Energies of the bottom-reflected signals have been calculated for varying angles of incidence and the corresponding reflectivities produced. Results from the Tyrrhenian Sea and from north of Puerto Rico indicate the possibility that the sound velocity in the first-layer sediments is less than the sound velocity of the bottom water.

Beschreibung: The Bureau of Ships Under Contract NObsr-89464

Beschreibung: Also published as: Buoy Technology, Transactions 2nd International Buoy Technology Symposium/Exposition, Washington, D.C., September 18-20, 1967, pp.409-418, 1967.

Beschreibung: Since January 1965,a program has been underway at the Woods Hole Oceanographic Institution, to measure currents at a limited number of fixed sites on a year round basis. Initially, one site was instrumented with both surface and subsurface moorings. The program has now been expanded to 4 major sites, extending along 70°W, from 39°20 ' N to the Hatteras Abyssal Plain at 30°N . In nearly three years of operation, a total of 65 moorings have been placed at the working sites, for periods up to six months. Recoveries from these sites have provided many velocity records of excellent quality. The repetitive exposure of moorings of essentially similar design under relatively standardized conditions has served to define clearly the design and operational problems that are inherent in such a program. A brief account is given of some of the problems encountered in routine buoy setting operations, and some of the results obtained from the measurements.

Beschreibung: The Office of Naval Research under Contract N00014-66-C0241~ NR 083-004.

Beschreibung: The Woods Hole Oceanographic Institution has been using deepsea moored buoys for acquiring serial observations of ocean currents, temperature .and other data for over twelve years. A brief description of the deep-sea mooring program is given. The mooring statistics and performance are described. Mooring failures of 1970 and 1971 have been categorized and statistics on the modes and causes of failures are presented. The reliabilities of different types of moorings are computed and compared. The role of radio telemetry for the real-time measurement of mooring line tension and its use in checking the mooring status are discussed. Examples of potential design data like tension and currents recorded by moorings that failed are provided. Finally, recommendations for research and development needed to improve mooring reliability are given.

Beschreibung: Prepared for the Office of NavaZ Research under Contract N00014-66-C024lj NR 083-004.