Effects of the winter of 1976-1977 on the northwestern sargasso sea

A survey was conducted in the northwestern Sargasso Sea during the spring to assess the effect and extent of the winter cooling of 1976 to 1977 on the ocean. Newly formed, well-mixed layers of 18 degrees C water as deep as 550 meters were observed. The main thermocline south of the Gulf Stream was 100 to 150 meters deeper than it is on the average, which implies significant changes in the baroclinic transports.     

Gulf Stream Deflection by a Bottom Feature off Charleston, South Carolina

A topographic feature on the continental slope off Charleston at 32 degrees N persistently deflects the Gulf Stream seaward, with the inshore surface thermal front deflected east or south of east in 27 of the 39 cases examined. Meanders often form downstream of the deflection, suggesting that the "Charleston bump" induces Gulf Stream fluctuations.     

Bottom Velocity Observations Directly under the Gulf Stream

Speeds as high as 44 centimeters per second were observed 200 meters above the ocean bottom under the Gulf Stream at 70 degrees W longitude and were associated with time-dependent motion that had a speed range of 40 centimeters per second and a time scale of about 30 days. These deep current fluctuations appear to be coupled with fluctuations in the surface position of the Stream and with surface and bottom current fluctuations 200 kilometers to the north.     

A Western boundary current in the gulf of Mexico

The curl of the wind stress over the Gulf of Mexico, during the winter and again in the summer, is similar to that over the central North Atlantic Ocean. An anticyclonic gyre is nearly always found in the western gulf, and we suggest that there is a typical western boundary current, similar in many important respects to the Gulf Stream. The flow appears to be strongest in winter and summer, in phase with the wind curl forcing, and there is evidence that this response is at least partially baroclinic. The deep baroclinic gyre persists when the wind curl vanishes. The winter transport is roughly half that of the Florida Current.     

Deep, zonal subequatorial currents

Large-scale, westward-extending tongues of warm (Pacific) and cold (Atlantic) water are found between 2000 and 3000 meters both north and south of the equator in the Pacific and Atlantic oceans. They are centered at 5 degrees to 8 degrees north and 10 degrees to 15 degrees south (Pacific) and 5 degrees to 8 degrees north and 15 degrees to 20 degrees south (Atlantic). They are separated in both oceans by a contrasting eastward-extending tongue, centered at about 1 degrees to 2 degrees south, in agreement with previous helium isotope observations (Pacific). Thus, the indicated deep tropical westward flows north and south of the equator and eastward flow near the equator may result from more general forcing than the hydrothermal forcing previously hypothesized.     

Vertical distribution and isotopic composition of living planktonic foraminifera in the Western north atlantic

Thirteen species of planktonic foraminifera collected with vertically stratified zooplankton tows in the slope water, Gulf Stream cold core ring, and northern Sargasso Sea show significant differences in their vertical distributions in the upper 200 meters of these different hydrographic regimes. Gulf Stream cold core rings may be responsible for a southern displacement of the faunal boundary associated with the Gulf Stream when reconstructed from the deep-sea sediment record. Oxygen isotope analyses of seven species reveal that nonspinose species (algal symbiont-barren) apparently calcify in oxygen isotope equilibrium, whereas spinose species usually calcify out of oxygen isotope equilibrium by approximately -0.3 to -0.4 per mil in delta(18)O values. The isotope data indicate that foraminifera shells calcify in depth zones that are significantly narrower than the overall vertical distribution of a species would imply.     

Mercury distribution in the gulf stream

Measurements of reactive mercury in ocean water in the Gulf Stream at depths from 250 to 4460 meters revealed lower and more consistent concentrations than have been reported in the western Atlantic. The mean and standard deviation of 24 values in a vertical profile were 4.1 +/- 1.0 nanograms per liter. A correlation was found between variations in mercury and silicate, suggesting a common link in their marine geochemistry.     

Temporal variability of the Atlantic meridional overturning circulation at 26.5 degrees N

The vigor of Atlantic meridional overturning circulation (MOC) is thought to be vulnerable to global warming, but its short-term temporal variability is unknown so changes inferred from sparse observations on the decadal time scale of recent climate change are uncertain. We combine continuous measurements of the MOC (beginning in 2004) using the purposefully designed transatlantic Rapid Climate Change array of moored instruments deployed along 26.5 degrees N, with time series of Gulf Stream transport and surface-layer Ekman transport to quantify its intra-annual variability. The year-long average overturning is 18.7 +/- 5.6 sverdrups (Sv) (range: 4.0 to 34.9 Sv, where 1 Sv = a flow of ocean water of 10(6) cubic meters per second). Interannual changes in the overturning can be monitored with a resolution of 1.5 Sv.     

North atlantic ice-rafting: a major change at 75,000 years before the present

During the last interglacial-to-glacial climatic cycle [127,000 to 10,000 years before the present (B.P.)], the fundamental geographic shift in the main axis of ice-rafting deposition occurred at 75,000 years B.P. An earlier meridional depositional maximum along the Greenland-Newfoundland coasts was superseded by a nearly zonal and much stronger axis some 1500 kilometers to the south along 40 degrees N to 50 degrees N. Both depositional patterns are best explained by cyclonic flow in the subpolor gyre, with the depositional shift related to the retreat of warm, ice-melting North Atlantic drift water from the northwestern half of the gyre. Similar shifts must have characterized preceding interglacial-glacial cycles.     

Subsurface circulation in the somali current

Direct velocity measurements were made at intermediate depths along the East African coast from March to July 1979. Strong time-dependent flows with multiple reversals in direction were found in the upper 1000 meters between 3 degrees N and 4 degrees S. At 700 meters, there may be a connection between the southwestward coastal current and an equatorial jet observed at 49 degrees E, the latter turning south near the coast. North of 3 degrees N little spatial organization of the flow can be recognized.     

Ocean current monitoring employing a new satellite sensing technique

The very-high-resolution radiometer on the NOAA-2 (National Oceanic and Atmospheric Administration) satellite has recently obtained imagery in the visible channel containing sunglint over a major portion of the coastal waters off the eastern seaboard of the United States. An abrupt change in surface roughness has been observed at the shoreward edge of the Gulf Stream Current from Florida to Cape Hatteras that results from the opposition of waves propagating against the flow of the Gulf Stream.     

高寒地区砌体住宅的节能体型与朝向设计

针对高寒地区进行了节能住宅建筑体型系数影响因素的分析,找出了住宅长、宽、高对建筑体型系数的影响规律,认为高寒地区住宅建筑宽度以9.6～12.0m为宜,长度以60m较为适宜,高度以17m(6层)为宜。根据住宅冬季得热与夏季防热的节能要求,进行了高寒地区建筑适宜朝向的计算,结合冬季与夏季主导风向的影响,给出了高寒地区(以大庆为例)节能住宅宜选择南至南偏西7.4°为其设计朝向。     

Manganese pavements on the blake plateau

Dredge samples and photographs from the Blake Plateau, off the southeast coast of the United States, indicate that a layer of manganese oxide forms pavement that may be continuous over an area af about 5000 square kilometers. The manganese pavement grades into round manganese nodules to the south and east and into phosphate nodules to the west. The Gulf Stream probably maintains a very unusual environment that prohibits deposition of clastic sediment and permits accretion of manganese pavements.     

Gulf stream cold-core rings: their physics, chemistry, and biology

Cyclonic Gulf Stream rings are energetic eddies in the warm Sargasso Sea consisting of a ring of Gulf Stream water surrounding a core of cold Slope Water. Initially a ring core has the characteristics of the Slope Water; it is rich in plants, animals, and nutrients. As a ring decays the Slope Water properties of its core are gradually replaced by those of the Sargasso Sea, where standing crops of plants, animals, and nutrients generally are low. Although the decay rate suggests a rather long lifetime (2 to 4 years), the usual death of a ring comes when it rejoins the Gulf Stream after 6 to 12 months.     

Seasat scanning multichannel microwave radiometer: results of the gulf of alaska workshop

The scanning multichannel microwave radiometer results for the Gulf of Alaska Seasat Experiment Workshop are quite encouraging, especially in view of the immaturity of the data-processing algorithms. For open ocean, rain-free cells of highest-quality surface truth wind determinations exhibit standard deviations of 3 meters per second about a bias of 1.5 meters per second. The sea-surface temperature shows a standard deviation of approximately 1.5 degrees C about a bias of 3 degrees to 5 degrees C under a variety of changing meteorological conditions.     

Gulf stream: velocity fluctuations during the late cenozoic

Biostratigraphic analysis of seven piston cores from the southeastern Blake Plateau suggests that the upper Miocene to Recent sedimentary section at this location represents a history of deposition of calcareous ooze alternating with current-induced nondeposition or erosion. This record is primarily a result of long-term fluctuations in the velocity of the western boundary current or Gulf Stream, which sweeps the plateau. High-velocity phases of this current system, as signaled by hiatuses in the section, lie within the time limits 4.8 to 6.1, 3.9 to 4.4, 2.3 to 2.9, and 0 to 1.5 million years before present (B.P.). These time intervals are coeval with dated episodes of climatic decline and glaciation. The most intense acceleration of the Gulf Stream, as indicated by deep erosion of the Blake Plateau, occurred in the latest Miocene to earliest Pliocene (4.8 to 6.1 million years B.P.) in conjunction with a major expansion of the Antarctic ice cap. Subsequent accelerations of the Gulf Stream coincide with early Pliocene cooling in the Southern Hemisphere, worldwide expansion of high-altitude-high-latitude glaciers in the late Pliocene, and the classical glaciations of the Pleistocene. An additional, protracted increase in the average velocity of the Gulf Stream, which began in the late Miocene and culminated in the mid-Pliocene (about 3.8 million years B.P.), can be attributed to the gradual emergence of the Central American isthmus.     

Agglomeration of ash in fluidized beds gasifying coal: the godel phenomenon

In a bed of anthracite or bituminous coke fluidized by air at 10 to 15 meters per second at 1200 degrees to 1400 degrees C, molten ash forms beads on the surface of a coke particle, some exuding from its interior. The beads merge and detach them-selves to grow further as loose fluidized ash agglomerates of low carbon content.     

Counterclockwise circulation in the pacific subantarctic sector of the southern ocean

The distribution of isohalines in the upper 500 meters of Pacific subantarctic waters can be interpreted as evidence for an endemic counterclockwise circulation, the westward component of which is at 40 to 45 degrees south latitude. The distributions of a number of lanternfish species (family Myctophidae) lend support to such an interpretation.     

Isotopic composition of old ground water from lake agassiz: implications for late pleistocene climate

A uniform oxygen isotope value of -25 per mil was obtained from old ground water at depths of 20 to 30 meters in a thick deposit of clay in the southern part of the glacial Lake Agassiz basin. The lake occupied parts of North Dakota and southern Manitoba at the end of the last glacial maximum and received water from the ice margin and the interior plains region of Canada. Ground water from thick late Pleistocene-age clay deposits elsewhere, a till in southern Saskatchewan, and a glaciolacustrine deposit in northern Ontario show the same value at similar depths. These sites are at about 50 degrees N latitude, span a distance of 2000 kilometers, and like the Lake Agassiz sites, have a ground-water velocity of less than a few millimeters per year. The value of -25 per mil is characteristic of meltwater impounded in the southern basin of Lake Agassiz. This value corresponds to an estimated air temperature of -16 degrees C, compared with the modern temperature of 0 degrees C for this area.     

Seasat synthetic aperture radar: ocean wave detection capabilities

A preliminary assessment has been made of the capability of the Seasat synthetic aperture radar to detect ocean waves. Comparison with surface and aircraft measurements from five passes of the satellite over the Gulf of Alaska indicates agreement to within about - 15 percent in wavelength and about +/- 25 degrees in wave direction. These results apply to waves 100 to 250 meters in length propagating in a direction predominantly across the satellite track, in sea states with significant wave height (H((1/3))) in a range of 2 to 3.5 meters.