Showing papers by "Woods Hole Oceanographic Institution published in 1982"
TL;DR: In this paper, the vertical and seasonal distribution of planktonic foraminifera in the western North Atlantic has been investigated using data from the Panama Basin, where the authors used a multiple opening-closing net and environmental sensing system to collect 13 sets of eight vertically stratified oblique samples.
Abstract: A model1,2, which explains the vertical and seasonal distribution of planktonic foraminifera was developed using data from the western North Atlantic and is comprised of three tenets: (1) The conditions in the photic zone (upper 80–100 m) exclusively dictate planktonic foraminifera species composition and abundance throughout the water column. (2) Species are vertically stratified within the photic zone according to their temperature preference. Depth distribution according to temperature preference has been proposed by several authors3 based on isotope analyses of sediments. Due to seasonal temperature variations, seasonal variations in the δ18O composition of seawater, and species-specific isotope fractionation, rigorous proof of this hypothesis cannot be provided from sediment analyses alone. (3) The chlorophyll maximum is a major food source zone, which is preferentially exploited by foraminifera. Our data from the Panama Basin, which are presented here, are confirmation of this model. The Panama Basin in the eastern equatorial Pacific, which has a shallow and steep thermocline, was sampled for living planktonic foraminifera. A multiple opening–closing net and environmental sensing system (MOCNESS)4 was used to collect 13 sets of eight vertically stratified oblique samples. We report here the quantitative distribution and stable isotopic composition of planktonic foraminifera from four MOCNESS tows taken over 5 days, during August 1979 (RV Knorr cruise 73) at 5°20′ N, 8°50′ W. Each tow consisted of eight samples which integrated ∼12.5-m intervals from 0 to 100 m for MOC 126, 25-m intervals from 0 to 200 m for MOC 127, 100–150-m intervals from 0 to 1,000 m on MOC 128 and 250-m intervals from 0 to 2,000 m on MOC 131.
649 citations
TL;DR: In this article, the authors present a unification of evidences from three different shallow seas: Lake Ontario, the Mid-Atlantic Bight, and the Oregon shelf, whose circulation is explored through major cooperative experiments.
Abstract: Publisher Summary This chapter analyzes circulation in the coastal ocean Much of the observational evidence discussed in the chapter comes from three shallow seas: Lake Ontario, the Mid-Atlantic Bight, and the Oregon shelf These are coastal oceans, whose circulation is explored through major cooperative experiments The chapter presents a unification of evidences from these three different shallow seas The emphasis is on the dynamic principles that underlie the conceptual models found to be successful in quantitatively accounting for observations, that is, on the fundamental physics of flow phenomena in the coastal ocean The quasi-geostrophic model is presented to explain wind-driven transient currents Concepts related to coastal constraint, velocity distribution, longshore pressure gradients are explained Response of stratified water column to wind is also explained Linear theory models for trapped waves and propagating fronts are discussed Observational evidence on wave and front propagation is presented Concept of steady parallel flow over a straight continental shelf is described Shelf circulation as a boundary-layer problem is explained Mean circulation of a stratified fluid and mean circulation of the mid-Atlantic bight is also discussed
523 citations
TL;DR: In this article, the results of helium isotopic analyses in basaltic phenocrysts from the islands of Gough and Tristan da Cunha were reported and compared to mid-ocean ridge basalt (MORB).
Abstract: Isotopic variations in oceanic igneous rocks provide important constraints on models of oceanic mantle structure. Of particular interest is the global negative correlation between 87Sr/86Sr and 143Nd/144Nd, which has been used to estimate ‘bulk earth’ values1–3 for 87Sr/86Sr, 87Rb/88Sr and 143Nd/144Nd. Simple two-reservoir models have failed to explain all the isotopic variations, however, because of the complicated trends in Pb isotopes4–6. This has led to suggestions that recycled oceanic crust or sediments must be considered in these models7–9. We report here the results of helium isotopic analyses in basaltic phenocrysts from the islands of Gough and Tristan da Cunha. Because basalts from the islands lie near bulk earth on the Sr–Nd correlation diagram3, the study was initiated to characterize the helium isotopic signature of this component. Whereas the 3He in mantle gases is mostly primordial, the 4He is primarily radiogenic, having been produced by decay of 238U, 235U and 232Th. High 3He/4He ratios in igneous rocks therefore indicate primordial volatiles10,11. We believe that the present results are inconsistent with the notion that the mantle beneath Gough and Tristan da Cunha is primitive or undepleted relative to mid-ocean ridge basalt (MORB). Helium isotopic results on basaltic glasses and phenocrysts from the rift zone of Kilauea confirm the previously reported high values from this area12–15. We also report new analyses from Loihi Seamount (40km south-east of Kilauea), which does seem to be derived from a more primitive source. When these data are combined with values for MORBs (from ref. 16) and plotted with respect to 87Sr/86Sr, the observed trends offer insight into the different source regions for oceanic island basalts and the nature of mantle heterogeneity.
494 citations
TL;DR: Comparisons of carbon isotopic data on benthic foraminifera from Deep Sea Drilling Project sites 502 and 503 suggest that modern circulation patterns in the Caribbean and eastern Pacific developed by 3 million years ago in concert with changing tectonic, climatic, and biogeographic patterns.
Abstract: Comparisons of carbon isotopic data on benthic foraminifera from Deep Sea Drilling Project sites 502 (western Caribbean) and 503 (eastern Pacific) indicate that the difference between the Atlantic and the Pacific in the per mil enrichment in carbon-13 of total dissolved carbon dioxide increased about 6 million years ago and again 3 million years ago, when the difference reached the modern level (1 per mil). Comparisons of planktonic foraminiferal oxygen isotopic data for the Caribbean and the Pacific suggest that the salinity of Caribbean surface waters began increasing 4 million years ago, possibly in response to shoaling of the Panama isthmus. These results suggest that modern circulation patterns in the Caribbean and eastern Pacific developed by 3 million years ago in concert with changing tectonic, climatic, and biogeographic patterns.
476 citations
01 Mar 1982
TL;DR: In this article, a direct and two indirect methods of calculating oceanic heat fluxes are compared and the direct method appears to be the most accurate: various independent, oceanographic estimates agree well with results from the air-sea exchanges.
Abstract: From oceanographic measurements of currents and temperature used in a direct calculation, ocean heat transport at 25°N in the Atlantic Ocean was estimated to be 1.1 × 1015W. The method used is discussed and the estimate revised to 1.2 × 1015W by using more complete data. An analysis indicates that the results have an error of at most 0.3 × 1015W and that contributions due to the eddy heat flux and seasonal variation are relatively small. The variation of mean meridional volume transport with depth at 25°N has been computed; the profile leads to the estimate of transport in various temperature classes and to some conclusions concerning the mechanisms of heat flux. The freshwater flux at 25°N has been computed; within error it is zero, a result that agrees with the literature. One direct and two indirect methods of calculating oceanic heat fluxes are compared. Indirect computations of heat flux based on air-sea interaction data provide good global coverage. Computations using satellite data are subject to large errors, but improved technology could make satellites an excellent means for monitoring global radiation. The direct method appears to be the most accurate: various independent, oceanographic estimates agree well with results from the air-sea exchanges. Ocean heat transport can be determined simply and accurately given appropriate measurements.
471 citations
TL;DR: Labrador Sea Water is the final product of the cyclonic circulation of Subpolar Mode Water in the open northern North Atlantic (McCartney and Talley, 1982) and is found throughout the North Atlantic Ocean north of 40°N and along its western boundary to 18°N as mentioned in this paper.
Abstract: Labrador Sea Water is the final product of the cyclonic circulation of Subpolar Mode Water in the open northern North Atlantic (McCartney and Talley, 1982). The temperature and salinity of the convectively formed Subpolar Mode Water decrease from 14.7°C, 36.08‰ to 3.4°C, 34.88‰ on account of the cumulative effects of excess precipitation and cooling. The coldest Mode Water is Labrador Sea Water, which spreads at mid-depths and is found throughout the North Atlantic Ocean north of 40°N and along its western boundary to 18°N. A vertical minimum in potential vorticity is used as the primary tracer for Labrador Sea Water. Labrador Sea Water is advected in three main directions out of the Labrador Sea: 1) northeastward into the Irminger Sea, 2) southeastward across the Atlantic beneath the North Atlantic current, and 3) southward past Newfoundland with the Labrador Current and thence westward into the Slope Water region, crossing under the Gulf Stream off Cape Hatteras. The Labrador Sea Water core is ...
470 citations
TL;DR: Data from a North Atlantic sediment core show that over the past 200,000 years there has been a continuous supply of nutrient-depleted waters into the deep North Atlantic, and indicates that the continental carbon inventory may have been less variable than previously suggested.
Abstract: Variations in the cadmium/calcium ratio of North Atlantic Deep Water are recorded in the fossil shells of benthic foraminifera. The oceanic distribution of cadmium is similar to that of the nutrients, hence the cadmium/calcium ratio in shells records temporal variations in nutrient distributions. Data from a North Atlantic sediment core show that over the past 200,000 years there has been a continuous supply of nutrient-depleted waters into the deep North Atlantic. The intensity of this source relative to nutrient-enriched southern waters diminished by about a factor of 2 during severe glaciations. This evidence combined with carbon isotope data indicates that the continental carbon inventory may have been less variable than previously suggested.
427 citations
TL;DR: Time-series sediment traps were deployed for an entire year at three depths at a deepwater station in the Panama Basin and suggest that suspended clays are efficiently scavenged from the water column by rapidly sinking organic aggregates.
Abstract: Time-series sediment traps were deployed for an entire year at three depths (890, 2590, and 3560 meters) at a deepwater station (3860 meters) in the Panama Basin. The amount of horizontal and lithogenic particulate material arriving at the three depths was seasonally pulsed and directly reflected changes in surface primary production. Two spikes of organic flux were simultaneously recorded at all three depths: (i) a period of high productivity during regional upwelling in February through March and (ii) an unusual bloom of a single species of coccolithophorid during June through July. This latter spike delivered approximately 25 grams of coccolith per square meter of area at a depth of 3860 meters during less than 60 days. The flux of lithogenic particles increased with increasing depth and was seasonally correlated to surface production and current direction, and not to the detritus discharged in river flow. The data suggest that suspended clays are efficiently scavenged from the water column by rapidly sinking organic aggregates.
407 citations
TL;DR: In this paper, the Prandtl-Batchelor theorem is applied to non-rotating, steady two-dimensional flow and the results of the derivations given here can apply only where internal heating is negligible, upon the potential density surface under consideration.
Abstract: The mean circulation of planetary fluids tends to develop uniform potential vorticity q in regions where closed time-mean streamlines or closed isolines of mean potential vorticity exist. This state is established in statistically steady flows by geostrophic turbulence or by wave-induced potential-vorticity flux. At the outer edge of the closed contours the expelled gradients of q are concentrated. Beyond this transition lies motionless fluid, or a different flow regime in which the planetary gradient of q may be dominant. The homogenized regions occur where direct forcing by external stress or heating within the closed isoline is negligible, upon the potential-density surface under consideration. In the stably stratified ocean such regions are found at depths greater than those of direct wind-induced stress or penetrative cooling. In ‘channel’ models of the atmosphere we again find constant q when mesoscale eddies cause the dominant potential-vorticity flux. In the real atmosphere the results here can apply only where internal heating is negligible. The derivations given here build upon the Prandtl–Batchelor theorem, which applies to non-rotating, steady two-dimensional flow. Supporting evidence is found in numerical circulation models and oceanic observations.
404 citations
01 May 1982
TL;DR: The major constituents of biogenic particles that settle through the water column of the ocean are carbonate tests, opaline shells, and particulate organic matter (cellular and amorphous) as mentioned in this paper.
Abstract: The major constituents of biogenic particles that settle through the water column of the ocean are carbonate tests, opaline shells, and particulate organic matter (cellular and amorphous). This paper describes the quality and quantity of such fluxes to the deep ocean and compares them with biogenic remains in the bottom sediment. Studies of samples collected during PARFLUX sediment trap experiments in the Atlantic and Pacific have shown that 60 to 90% of the total particulate flux is of biogenic origin; the contribution of biogenic materials decreases with increasing depth. Carbonate hard parts accounted for 30 to 60% and were the largest constituents in pelagic sediments at temperate and tropical areas. Combustible components ranged from 10 to 30% with zooplankton remains and fecal pellets accounting for the bulk of the organic flux. Amorphous fine particles were also significant in the organic flux. The atomic ratios of organic constituents in settling particles deviated systematically from the ‘Redfield ratio’ of 106:16:1 (C:N:P) for marine plankton. In the mesopelagic depths the ratio was 200:21:1, and in the bathypelagic depths the ratio was 300:33:1, with a wide range of variation in phosphorus.
The residence time of biogenic particles in the deep-ocean water columns is relatively short and the particles can be expected to arrive at the abyssal floor without major dissolution and remineralization (excepting small opal particles). Fine organic particles such as cell remains and pigmented granules are a major source of organic carbon and nitrogen at deep traps. Microscopic study suggests that the fine organic particles were once included in larger but loosely-formed particles that settled rapidly. Such particles dispersed from settling fecal pellets or similar particles are reintroduced into the water column resulting in ‘secondary’ suspended particles. Such particles may eventually be remineralized while in suspension. The decomposition rate of organic carbon in the deep water was estimated to be about 2.2 mg C m−2 day−1, a rate consistent with rates of oxygen consumption estimated by other investigators.
The bottom sediment is enriched in refractory lithogenic particles because of the remineralization of biogenic matter. A hypothetical benthic transition layer serves as a reservoir of benthic activity and can exist under certain conditions at the abyssal floor.
398 citations
TL;DR: In this paper, a volumetric census of the temperature-salinity characteristics of the North Atlantic by Wright and Worthington (1970) shows that waters characterized by certain segments of the T-S relationships have large volumes compared to those of other segments: the mode waters appear as layers with increased vertical separation between isopycnals-pycnostads.
Abstract: The warm waters of the subtropical and subpolar basins of the North Atlantic have tight regional temperature-salinity relationships, and are conventionally called the regional “Central Waters.” A volumetric census of the temperature-salinity characteristics of the North Atlantic by Wright and Worthington (1970) shows that waters characterized by certain segments of the T-S relationships have large volumes compared to those of other segments: volumetric “Mode Waters.” Such Mode Waters appear as layers with increased vertical separation between isopycnals-pycnostads. The present study reports on the existence of pycnostads in the central and eastern North Atlantic. These Subpolar Mode Waters are formed by deep winter convection in the subpolar North Atlantic, and participate in the upper water circulation of the northern North Atlantic. The seasonal outcropping of the pycnostads occurs within and adjacent to the North Atlantic Current, the Irminger Current, the East and West Greenland Currents, and...
TL;DR: In this paper, a sample of mid-ocean ridge basalt glass and diabase has been reacted with seawater at 150-300°C, 500 bar, and water/rock mass ratios of 50, 62, and 125, using experimental apparatus which allowed on-line sampling of solution to monitor reaction progress.
TL;DR: The combination of low algal biomass and strong pH buffering commonly found in most marine and many freshwater environments probably limits the possibilities for NH(3) toxicity to low alkalinity freshwaters and intensive algal cultures in which NH(4) is the main source of N. coli.
Abstract: The effect of free NH3 inhibition on short-term photosynthesis was investigated in three microalgal species: the freshwater chlorophyte Scenedesmus obliquus, the marine diatom Phaeodactylum tricornutum and the marine chlorophyte Dunaliella tertiolecta. By performing a series of assays at various concentrations of added NH4Cl and culture pH, we demonstrated that the inhibitory compound was free NH3 and that pH played no role in determining the magnitude of inhibition, other than in establishing the degree of dissociation of nontoxic NH4+ to toxic NH3. When corrections were made for pH, all three species displayed the same sigmoidal response curve to free NH3 concentration; 1.2 mM NH3 led to 50% reduction in photoassimilation of 14C. Based on literature values, some marine phytoplankton appear to be significantly more sensitive to free NH3 than were the test species, which are noted for their excellent growth characteristics. However, the combination of low algal biomass and strong pH buffering commonly found in most marine and many freshwater environments probably limits the possibilities for NH3 toxicity to low alkalinity freshwaters and intensive algal cultures in which NH4+ is the main source of N. Such conditions occur commonly in algal wastewater treatment systems.
TL;DR: In this article, the authors show that the concavity or convexity of sea cliff profiles is controlled by relative rates of erosion by marine and subaerial processes, as well as positions of more resistant strata in the cliffs.
Abstract: General concavity or convexity of sea-cliff profiles is controlled by relative rates of erosion by marine and subaerial processes, as well as by positions of more resistant strata in the cliffs. Profiles supplemented by on-site examination can establish the activity and dominance of erosional processes and indicate changes in regimen. A sharp angle at the sea-cliff base generally indicates active marine erosion, whereas a smooth curve at the base means that subaerial erosion may dominate. Talus shows absence of marine erosion. Studies of profiles can be useful for estimating stability for residences, railroads, and highways at the top, face, and base of sea cliffs. Generally increased erosion and retreat of sea cliffs are in prospect because of projected regionally wetter and stormier climate, rising sea level, and increased human activities.
TL;DR: In this article, tritium dating was used to determine the oxygen utilization rate in the North Atlantic subtropical gyre, and their implications regarding primary production and nutrient cycling in an oligotrophic system.
Abstract: If the observed distribution of dissolved oxygen in deep oceans below the euphotic zone is in stationary and steady state, then it can be assumed that the in situ consumption of oxygen is balanced by ‘ventilation’, or, in other words, physical transport of oxygen from regions of higher dissolved oxygen and ultimately the sea surface. It follows, therefore, that measurement or determination of those physical transport processes, coupled with observation of the oxygen distribution will lead to an estimate of the net oxygen utilization rate (OUR). The character of such an estimate is that it is a space and time average over scales governed by the nature (space and time scales) of the transport processes, the scale of the oxygen distribution, and the climatologic nature of the system. As such, one obtains an average which is characteristically of the order of 108 s, 108 cm or more, that is large compared with scales of biological variability. I report here some new determinations of oxygen utilization rates determined by tritium dating in the North Atlantic subtropical gyre, compare them with other and previous estimates, and discuss their implications regarding primary production and nutrient cycling in an oligotrophic system.
TL;DR: Oceanic macroaggregates sampled from the Sargasso Sea are associated with bacterial and protozoan populations up to four orders of magnitude greater than those present in samples from the surrounding water.
Abstract: Oceanic macroaggregates (marine snow and Rhizosolenia mats) sampled from the Sargasso Sea are associated with bacterial and protozoan populations up to four orders of magnitude greater than those present in samples from the surrounding water. Filamentous, curved, and spiral bacteria constituted a higher proportion of the bacteria associated with the particles than were found among bacteria in the surrounding water. Protozoan populations were dominated numerically by heterotrophic microflagellates, but ciliates and amoebas were also observed. Macroaggregates are highly enriched heterotrophic microenvironments in the oceans and may be significant for the cycling of particulate organic matter in planktonic food chains.
TL;DR: In this paper, two models of advection-diffusion in the oscillatory, sheared-velocity field of an internal wave are discussed and the authors develop intuition about the role of such currents in horizontal ocean mixing through the mechanism of shear dispersion.
Abstract: Two models of advection-diffusion in the oscillatory, sheared-velocity field of an internal wave are discussed. Our goal is to develop intuition about the role of such currents in horizontal ocean mixing through the mechanism of shear dispersion. The analysis suggests simple parameterizations of this process, i.e., those in Eqs. (7), (36) and (42). The enhanced horizontal diffusion due to the interaction of the vertical diffusion and vertical shear of the wave field can be described by an “effective horizontal diffusivity” which is equal to the actual horizontal diffusivity plus a term equal to the mean-square vertical shear of horizontal displacement times the vertical diffusivity, provided the vertical length scale of the horizontal velocity field is not too small. In the limit of small vertical length scale the expression reduces to Taylor's (1953) result in which the effective horizontal diffusivity is inversely proportional to the actual vertical diffusivity. The solutions also incidentally ...
TL;DR: In this article, a set of 35 basaltic glass samples dredged from the Mid-Atlantic Ridge between 28° and 53°N latitude were analyzed and the helium concentrations and helium isotopic ratios were determined.
TL;DR: Oxygen and carbon-isotopic analyses have been performed on the benthic foraminifer Planulina wuellerstorfi in seven Late Quaternary cores from the Vema Channel-Rio Grande Rise region as discussed by the authors.
TL;DR: Hole 504B provides a reference section for correlation of in situ petrological and geophysical studies with regional crustal models based on dredged samples and remote surveys; and, at least for the medium spreading-rate Costa Rica Rift, Hole 504B confirms that the main features of the upper part of an idealized ophiolite sequence occurs in the oceanic crust as mentioned in this paper.
Abstract: Hole 504B provides a reference section for correlation of in situ petrological and geophysical studies with regional crustal models based on dredged samples and remote surveys; and, at least for the medium-spreading-rate Costa Rica Rift, Hole 504B confirms that the main features of the upper part of an idealized ophiolite sequence occurs in the oceanic crust.
TL;DR: In this paper, temperature data spanning the entire Middle Atlantic Bight (MAB) during 1979 are used to study the structure and evolution of the cold pool, and both temperature data and direct current measurements suggest that the mean alongshore current has a minimum between Nantucket Shoals and Hudson Canyon.
Abstract: Temperature data spanning the entire Middle Atlantic Bight (MAB) during 1979 are used to study the structure and evolution of the cold pool. The Nantucket Shoals and New England Shelf appear to be the source of the coldest water found in the MAB in late winter. During the spring and summer, water within the cold pool in the New York Bight north of Hudson Canyon remains colder than any shelf water either to the northeast or southwest. Thus the coldest cold-pool water persists there as a remnant of winter-cooled water rather than being replenished by a colder upstream source, and south of Hudson Canyon, cold-pool temperatures decrease in June and July as colder water from upstream is advected southwestward along the coast. Both temperature data and direct current measurements suggest that the mean alongshore current has a minimum between Nantucket Shoals and Hudson Canyon. The alongshore variation of shelf topography appears to be responsible for the spatial variation in both the alongshelf drift s...
TL;DR: There was an inverse relationship between the levels of nitrogen and the carbohydrate content of the algal thalli, and within the protein pool, the phycoerythrin pigments appear important as a source of nitrogen when thalli are initially becoming nitrogen limited.
Abstract: Internal nitrogen pools in thalli of Gracilaria tikvahiae McLachlan were examined in three experiments as a function of total nitrogen content of the thallus, nitrogen deprivation, and nitrogen resupply. Amino acids and proteins appeared to form the major nitrogen storage pools in G. tikvahiae, while DNA appeared to be relatively unimportant in this regard. Inorganic nitrogen in the forms of NH4+ and NO3− was found in the thalli; however, its contribution to the total nitrogen, pools was small. Within the protein pool, the phycoerythrin pigments appear important as a source of nitrogen when thalli are initially becoming nitrogen limited. In general, there was an inverse relationship between the levels of nitrogen and the carbohydrate content of the algal thalli.
TL;DR: In this paper, the abundance of U. peregrina and water depth or temperature are not the same everywhere, and no correlation with dissolved oxygen in the water column is seen on the United States continental slope and rise.
Abstract: Several bathymetrically consistent Recent benthic foraminiferal biofacies have been recognized from the continental slope south-east of Cape Cod. Faunal assemblages are dominated by Globobulimina / Bulimina (upper slope; less than 1,000 m) and Uvigerina peregrina (lower slope-uppermost rise; water depths between 1,000 and 2,500 m). The Globobulimina / Bulimina assemblage coincides with the oxygen minimum zone; this agrees with the occurrence of Globobulimina in Mediterranean sapropels, organic-rich sediments deposited under anoxic conditions. Previous studies have noted the association of U. peregrina with bathyal water depths, deep-water temperatures of 3 to 4 ° C, and water of low oxygen content. However, correlations between abundance of U. peregrina and water depth or temperature are not the same everywhere, and no correlation with dissolved oxygen in the water column is seen on the United States continental slope and rise. The highest abundances of U. peregrina coincide with maxima of organic carbon and silt within the slope sediments. This suggests that the distribution of U. peregrina in this region may be influenced more by low oxygen in the sediments, rather than by low oxygen content of the overlying water.
TL;DR: The brain and eye of swordfish are warmer than the water, and a tissue that heats the brain is associated with one of the eye muscles that protects the central nervous system from rapid cooling during daily vertical excursions.
Abstract: The brain and eye of swordfish are warmer than the water. Associated with one of the eye muscles is a tissue that heats the brain. This brain heater is rich in mitochondria and cytochrome c and is supplied with blood through a vascular heat exchanger. It protects the central nervous system from rapid cooling during daily vertical excursions which may take the swordfish through a wide temperature range.
TL;DR: Authigenic U is remineralized within the bathypelagic layers at the open ocean sites studied in this article, however, in the Panama Basin, an upwelling area with high biological productivity, the rate of reminification of authigenic u in the deep sea is insufficient to produce a measurable concentration gradient between surface and deep waters within the mixing time of oceans.
TL;DR: In this article, the agreement between trapped wave theory and observation is studied for the case of observations made off Peru during the 1977 CUEA JOINT-II experiment using a numerical model with realistic, horizontally uniform stratification and realistic bottom topography.
Abstract: The agreement between coastal trapped wave theory and observation is studied for the case of observations made off Peru during the 1977 CUEA JOINT-II experiment Wave properties are calculated using a numerical model with realistic, horizontally uniform stratification and realistic bottom topography These properties are then explored as a function of the ratio of the first internal Rossby radius of deformation to the shelf-slope width The agreement of observed and calculated first-mode, free wave phase speeds (230 cm s−1) is excellent, while modal structures agree more poorly A forced wave calculation, using observed winds and currents as input, is used to hindcast alongshore currents and sea level in the frequency band where Smith (1978) observed free coastal trapped waves during 1977 The model suggests that most of the observed sea level and alongshore velocity fluctuations in the 5–10 day period band are due to free waves originating equatorward of 5°'s, while winds between 5°'s and
01 Jun 1982
TL;DR: Antarctic Intermediate Water and Subantarctic Mode Water were studied by examining their modal density and modal salinity characteristics around Antarctic as mentioned in this paper. But the study focused on 15 regions between 40 and 45°S.
Abstract: Antarctic Intermediate Water and Subantarctic Mode Water are studied by examining their modal density and modal salinity characteristics around Antarctic. The study focuses on 15 regions between 40 and 45°S. Circumpolar distributions for the cores of Antarctic Intermediate and Subantarctic Mode Water and potential temperature-salinity diagrams provide a detailed description of the water masses. The modal salinity and density change gradually across each of the three oceans, presumably due to the alteration of a single water mass. Large changes occur in the transition regions in the Drake Passage, south of Africa, and south of New Zealand. These large changes are due to the presence of distinctly different water masses.
Thermohaline finestructure is associated with the water mass transitions. The finestructure intensity between the 27.10 and 27.40 σθ isopycnals is quantified. Although continuous temperature-depth data are not available for the entire region the study indicates that the most intense finestructure occurs in regions of large water mass contrast and decreases by an order of magnitude away from them. Increased vertical temperature gradient variances were observed near a 100-km diameter eddy south of New Zealand.
TL;DR: Data are consistent with the hypothesis that phytoplankton may be able to exploit short-lived nutrient micropatches and may be growing at relatively rapid rates in oceanic waters.
Abstract: A series of 15NH,+ uptake studies with four species of marine phytoplankton, Dunaliella tertiolecta (Dun), Phaeodactylum tricornutum (TFX-l), Chaetoceros simplex (BBsm), and Thalassiosira weissflogii (Actin), maintained in NH,+-limited continuous cultures at varying specific growth rates (p) and temperatures, was done to examine the time-dependency of NH,+ uptake and the relationship between physiological state and NH,+ uptake. The effect of growth rate on short term NH,+ uptake varied tremendously with species, but the trend of increasing V’,u:b with decreasing relative growth rate (p:b) was demonstrated by all species down to p = 0.25% of ,L The diatoms, especially, were capable of sustaining a high V’,,:,& even at very high relative growth rates. Growth rate also influenced the time-course of NH, I uptake: for cells grown at =0.20-0.35 ,& an enhancement in NH,+ uptake was observed in the first 5 min of incubation, but not for cells at >0.90 ,L These data are consistent with the hypothesis that phytoplankton may be able to exploit short-lived nutrient micropatches and may be growing at relatively rapid rates in oceanic waters.
TL;DR: The high rates of defecation, large size and rapid sedimentation of salp fecal pellets make them likely mechanisms for rapid transport of small particulate matter from surface waters to deep water and the benthos.
Abstract: Rates of fecal pellet production have been recorded from seven species of oceanic salps feeding on natural diets. Expressed as μg C defecated per mg salp body C per hour, the values range between 3.7 and 27.7. Carbon: nitrogen ratios of the salp fecal pellets average 11.4; the organic matter of the pellets is mainly protein and carbohydrate. Sinking velocities of the pellets are very high, ranging from 320 to 2 238 m d-1 for pellets from three species. However, the pellets sink slower than would be predicted from extrapolation of rates for crustacean pellets, probably due to the shape of the pellets and their density. The high rates of defecation, large size and rapid sedimentation of salp fecal pellets make them likely mechanisms for rapid transport of small particulate matter from surface waters to deep water and the benthos.
TL;DR: It is suggested that the hydrothermal vents of the South Pacific Rise produce a beta-governed circulation at mid-depth, and that perhaps the associated plume of excess3He (Lupton and Craig [1]) points westward because of the dynamics of this circulation rather than as a passive tracer.