Westward bottom currents along the margin of the South Shetland Island Arc

Existing information is synthesized and new data presented to describe the flow of near-bottom water from the Weddell Sea into the Scotia Sea and westward through Drake Passage along the continental slope. The water characteristics and currents along the northern margins of the South Sandwich Island Arc are examined. Long-term current measurements in the bottom waters at locations over the outer shelf and slope and along the continental rise show persistent flow from Atlantic to Pacific along isobaths at speeds of 10–20 cm s−1. Three sources for the waters in these currents are identified and discussed. At the deepest levels, Weddell Sea Deep Water enters the Scotia Sea near 40°W through a depression in the South Scotia Arc and then flows westward, constrained by the bottom topography. This cold, fresh, oxygenated bottom water then flows west to enter Drake Passage via a gap in the Shackleton Fracture Zone at the base of the continental slope northwest of Elephant Island. Mid-depth water may flow from the Weddell Sea to the Scotia Sea through the Powell Basin (sill depth approximately 2000 m) located west of South Orkney Island near 48°W. The westward flowing waters along the shelf and upper continental slope, which are denser than those immediately offshore, may be a continuation of the Polar Slope Current from the Weddell Sea or may be derived principally by convection from the shelves of the South Sandwich Island Arc. A vertical section north of Elephant Island shows downslope convection off the shelf, analogous to the observed at many locations around Antartica

Some features of the deep water in the Gulf of Mexico

In the central Gulf of Mexico, 52 stations having depths greater than 1500 m were occupied within a seven-week period. The data for waters below sill depth (2000 m) show that the ranges of potential temperature and salinity are very limited, although weak vertical gradients indicate a slight positive stability...

The International Oceanographic Tables

Tables I and II of the series International Oceanographic Tables have been in print for longer than a year. The oceanographic community is indebted to members of the Joint Panel on Oceanographic Tables and Standards (JPOTS), particularly to its chairman, Roland A. Cox, and to others, for the work represented by these tables

A characterization of the Gulf of Mexico waters in winter

The results of a rapid survey of the Gulf of Mexico in the winter of 1962 are presented. Variations in the characteristics of the water in several core layers are described. Circulation has been examined on the basis of dynamic computations and G.E.K. measurements. In the eastern Gulf, water enters through Yucatan Strait and leaves through Florida Strait, flowing in an anticyclonic loop that extends well into the Gulf...

A detached eddy in the Gulf of Mexico

This note presents some preliminary results of a still-incomplete detailed analysis of observations on the property distributions and currents in the eastern part of the Gulf of Mexico, with primary emphasis on the Eastern Loop Current. Observations were obtained aboard the R/V ALAMINOS in June 1966, 1967

Hydrographic Properties and Inferred Circulation Over the Northeastern Shelves of the Gulf of Mexico During Spring to Midsummer of 1998

A hydrographic cruise was conducted 5-16 May 1998 over the northeastern shelves of the Gulf of Mexico, Observed distributions of temperature, salinity, oxygen, and nutrients were consonant with prior occurrences of upwelling, particularly near the head of DeSoto Canyon. Shipboard, moored, and satellite observations indicated these upwelling events were related to the presence of an anticyclonic circulation feature over the canyon. In addition, several cool water events occurred during spring in the nearshore region west of Pensacola; these may be attributed to atmospheric effects. High river discharges from rivers west of the Apalachicola during winter and spring likely resulted in the extensive surface distributions of low-salinity water observed from Mississippi Sound to Cape San Bias during the cruise. The combination of cool bottom temperatures and relatively low surface salinities over the inshore shelf west of Cape San Bias, with the usual seasonal warming, resulted in enhanced vertical stability. This stability likely inhibited vertical mixing and contributed to the development of the relatively low concentrations of dissolved oxygen observed in the bottom waters

Maturing Technologies for Stirling Space Power Generation

Stirling Radioisotope Power Systems (RPS) are being developed as an option to provide power on future space science missions where robotic spacecraft will orbit, flyby, land or rove. A Stirling Radioisotope Generator (SRG) could offer space missions a more efficient power system that uses one fourth of the nuclear fuel and decreases the thermal footprint of the current state of the art. The RPS Program Office, working in collaboration with the U.S. Department of Energy (DOE), manages projects to develop thermoelectric and dynamic power systems, including Stirling Radioisotope Generators (SRGs). The Stirling Cycle Technology Development (SCTD) Project, located at Glenn Research Center (GRC), is developing Stirling-based subsystems, including convertors and controllers. The SCTD Project also performs research that focuses on a wide variety of objectives, including increasing convertor temperature capability to enable new environments, improving system reliability or fault tolerance, reducing mass or size, and developing advanced concepts that are mission enabling. Research activity includes maturing subsystems, assemblies, and components to prepare them for infusion into future convertor and generator designs. The status of several technology development efforts are described here. As part of the maturation process, technologies are assessed for readiness in higher-level subsystems. To assess the readiness level of the Dual Convertor Controller (DCC), a Technology Readiness Assessment (TRA) was performed and the process and results are shown. Stirling technology research is being performed by the SCTD Project for NASA's RPS Program Office, where tasks focus on maturation of Stirling-based systems and subsystems for future space science missions

Transfer/Breakup Modes in the 6He+209Bi Reaction Near and Below the Coulomb Barrier

Reaction products from the interaction of 6He with 209Bi have been measured at energies near the Coulomb barrier. A 4He group of remarkable intensity, which dominates the total reaction cross section, has been observed. The angular distribution of the group suggests that it results primarily from a direct nuclear process. It is likely that this transfer/breakup channel is the doorway state that accounts for the previously observed large sub-barrier fusion enhancement in this system.Comment: 4 pages; 3 figure