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Structure And Trophic Ecology Of A Low Latitude Midwater Decapod And Mysid Assemblage, Thomas L. Hopkins, Mark E. Flock, John V. Gartner Jr, Joseph J. Torres Jun 1994

Structure And Trophic Ecology Of A Low Latitude Midwater Decapod And Mysid Assemblage, Thomas L. Hopkins, Mark E. Flock, John V. Gartner Jr, Joseph J. Torres

Marine Science Faculty Publications

The micronektonic crustacean assemblage in the eastern Gulf of Mexico is an extension of the low latitude Atlantic and Caribbean faunas. Species showed highly varying diel distribution patterns ranging from a strong vertical migration to the epipelagic zone to absence of any migration resulting in a permanent residence deep in the mesopelagic zone. As in other low latitude areas, decapod species with variegated pigment patterns centered above 650 m during the day, whereas 'all-red' species centered below this depth. Standing stocks were estimated at 0.18 g dry wt m-2 and 3 ind. m-2 in the upper 1000 m. Diet analysis …

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Interpretation Of The Coastal Zone Color Scanner Signature Of The Orinoco River Plume, Herschel T. Hochman, Frank E. Muller-Karger, John J. Walsh Apr 1994

Interpretation Of The Coastal Zone Color Scanner Signature Of The Orinoco River Plume, Herschel T. Hochman, Frank E. Muller-Karger, John J. Walsh

Marine Science Faculty Publications

The Caribbean Sea is an area that traditionally has been considered oligotrophic, even though the Orinoco River contributes large quantities of fresh water, nutrients, and other dissolved materials to this region during the wet boreal (fall) season. Little is known about the impact of this seasonal river plume, which extends from Venezuela to Puerto Rico shortly after maximum discharge. Here we present results from a study of the bio-optical characteristics of the Orinoco River plume during the rainy season. The objective was to determine whether the coastal zone color scanner (CZCS) and the follow-on sea-viewing wide-field-of-view sensor (SeaWiFS) satellite instrument …

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The Effects Of Temporal Variability Of Mixed Layer Depth On Primary Productivity Around Bermuda, W. Paul Bissett, Mark B. Meyers, John J. Walsh, Frank E. Muller-Karger Apr 1994

The Effects Of Temporal Variability Of Mixed Layer Depth On Primary Productivity Around Bermuda, W. Paul Bissett, Mark B. Meyers, John J. Walsh, Frank E. Muller-Karger

Marine Science Faculty Publications

Temporal variations in primary production and surface chlorophyll concentrations, as measured by ship and satellite around Bermuda, were simulated with a numerical model. In the upper 450 m of the water column, population dynamics of a size‐fractionated phytoplankton community were forced by daily changes of wind, light, grazing stress, and nutrient availability. The temporal variations of production and chlorophyll were driven by changes in nutrient introduction to the euphotic zone due to both high‐ and low‐frequency changes of the mixed layer depth within 32°‐34°N, 62°‐64°W between 1979 and 1984. Results from the model derived from high‐frequency (case 1) changes in …

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A Numerical Analysis Of Shipboard And Coastal Zone Color Scanner Time Series Of New Production Within Gulf Stream Cyclonic Eddies In The South Atlantic Bight, J. Raymond Pribble, John J. Walsh, Dwight A. Dieterle, Frank E. Muller-Karger Apr 1994

A Numerical Analysis Of Shipboard And Coastal Zone Color Scanner Time Series Of New Production Within Gulf Stream Cyclonic Eddies In The South Atlantic Bight, J. Raymond Pribble, John J. Walsh, Dwight A. Dieterle, Frank E. Muller-Karger

Marine Science Faculty Publications

Eddy-induced upwelling occurs along the western edge of the Gulf Stream between Cape Canaveral, Florida, and Cape Hatteras, North Carolina, in the South Atlantic Bight (SAB). Coastal zone color scanner images of 1-km resolution spanning the period April 13-21, 1979, were processed to examine these eddy features in relation to concurrent shipboard and current/temperature measurements at moored arrays. A quasi-one-dimensional (z), time-dependent biological model, using only nitrate as a nutrient source, has been combined with a three-dimensional physical model in an attempt to replicate the observed phytoplankton field at the northward edge of an eddy. The model is applicable only …

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Seasonal And Diel Abundance Of Viruses And Occurrence Of Lysogeny/Bacteriocinogeny In The Marine Environment, Sunny C. Jiang, John H Paul Jan 1994

Seasonal And Diel Abundance Of Viruses And Occurrence Of Lysogeny/Bacteriocinogeny In The Marine Environment, Sunny C. Jiang, John H Paul

Marine Science Faculty Publications

To understand the role of viruses in the marine environment, it is important to know the factors affecting their temporal distribution and the abundance of lysogens. We therefore performed a seasonal and a diel study on viral distribution in Tampa Bay, Florida, USA, and detected the abundance of lysogens and bacteriocinogens amongst marine bacterial isolates from diverse marine environments. We investigated the distribution of viruses, bacterial direct counts, chlorophyll a (chl a), salinity and temperature during a 13 mo period in the Tampa Bay estuary. The results indicated that the viral population had a strong seasonal pattern with the highest …

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Modeling Rotating Flows With Neutral And Unstable Stratification, Samuel Hassid, Boris Galperin Jan 1994

Modeling Rotating Flows With Neutral And Unstable Stratification, Samuel Hassid, Boris Galperin

Marine Science Faculty Publications

We investigate the effect of rotation on the structure of turbulence in neutral and convective mixed layers and assess the applicability of the Reynolds stress turbulence closure models to studies of deep convection. Unlike in the case of stable stratification, where rotational contribution is limited (Galperin et al., 1989), in neutral and convective flows this contribution is significant. The rotational terms endow eddy viscosity and eddy diffusivity with tensorial properties and algebraic complexity. In the present study we thoroughly investigate the mathematical features of this tensorial eddy viscosity-eddy diffusivity formulation. To ensure physical readability of the model, we found it …

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Comparison Of Topex Sea Surface Heights And Tide Gauge Sea Levels, Gary T. Mitchum Jan 1994

Comparison Of Topex Sea Surface Heights And Tide Gauge Sea Levels, Gary T. Mitchum

Marine Science Faculty Publications

TOPEX sea surface height data from the first 300 days of the mission are compared to sea level data from 71 tide gauges. The initial comparison uses sea surface height data processed according to standard procedures as defined in the users handbook. It is found that the median correlations for island and for coastal tide gauges are 0.53 and 0.42, respectively. The analogous RMS differences between the two data sets are 7.9 and 10.4 cm. The comparisons improve significantly when a 60-day harmonic is fit to the differences and removed. This period captures aliased M2 and S2 tidal energy that …

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Ribulose-Bisphosphate Carboxylase Gene Expression In Subtropical Marine Phytoplankton Populations, Scott L. Pichard, Marc E. Frischer, John H Paul Nov 1993

Ribulose-Bisphosphate Carboxylase Gene Expression In Subtropical Marine Phytoplankton Populations, Scott L. Pichard, Marc E. Frischer, John H Paul

Marine Science Faculty Publications

Oceanic phytoplankton are known to fix CO2 primarily through the action of the enzyme ribulose-1,5-bisphosphate carboxylase (RuBPCase). The amino acid and nucleotide sequence of the large subunit of this enzyme have been conserved across the evolution of the chlorophytic plants (from cyanobacteria to higher plants via green algae) with approximately 80 and 70 % homology at the amino acid and nucleotide levels respectively. To understand the molecular regulation of this enzyme in phytoplankton, we have measured levels of the RuBPCase large subunit (rbcL) mRNA and DNA, in combination with rates of photosynthetic CO2 fixation, autofluorescent cell counts, and chlorophyll a …

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A Description Of Coads Surface Meteorological Fields And The Implied Sverdrup Transports For The Atlantic Ocean From 30°S To 60°N, Dennis A. Mayer, Robert H. Weisberg Oct 1993

A Description Of Coads Surface Meteorological Fields And The Implied Sverdrup Transports For The Atlantic Ocean From 30°S To 60°N, Dennis A. Mayer, Robert H. Weisberg

Marine Science Faculty Publications

Using COADS data spanning 1947-1988, we describe the regional nature of the Atlantic Ocean wind-driven circulation between 30-degrees-S and 60-degrees-N and its annual and interannual variability. The Sverdrup streamfunction defines the circulation gyres. Our focus is on three central gyres: the Northern Hemisphere anticyclonic subtropical gyre, the cyclonic tropical gyre just north of the equator, and the clockwise equatorial gyre straddling the equator. This rendition of the Sverdrup streamfunction, computed with constant drag coefficient and air density, compares favorably with that from other climatologies. In the Straits of Florida, analyses suggest that differences between the annual cycle in Sverdrup transport …

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Viruses, Bacterioplankton, And Phytoplankton In The Southeastern Gulf Of Mexico: Distribution And Contribution To Oceanic Dna Pools, J. Boehme, M. E. Frischer, S. C. Jiang, C. A. Kellogg, S. Pichard, J. B. Rose, C. Steinway, John H. Paul Jul 1993

Viruses, Bacterioplankton, And Phytoplankton In The Southeastern Gulf Of Mexico: Distribution And Contribution To Oceanic Dna Pools, J. Boehme, M. E. Frischer, S. C. Jiang, C. A. Kellogg, S. Pichard, J. B. Rose, C. Steinway, John H. Paul

Marine Science Faculty Publications

Little is known concerning the factors which might control the distribution of viral abundance in oceanic environments and the relationship of viruses to the oceanic DNA pool. We have measured the distribution of viruses, bacterioplankton and phytoplankton in the subtropical southeastern Gulf of Mexico and related these parameters to the distribution of DNA (dissolved and particulate) in these waters. Viral direct counts were 4.6 to 27 x 10(6) ml-1 in Tampa Bay (Florida, USA), 3.8 to 8.5 x 10(5) ml-1 in all oceanic euphotic zone samples and 1.4 to 4.7 x 10(4) ml-1 in deep (200 to 2500 m) waters, …

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Seasonal-Variations In Equatorial Atlantic-Ocean Zonal Volume Transport At 28-Degrees-W, T. Y. Tang, Robert H. Weisberg Jun 1993

Seasonal-Variations In Equatorial Atlantic-Ocean Zonal Volume Transport At 28-Degrees-W, T. Y. Tang, Robert H. Weisberg

Marine Science Faculty Publications

Zonal volume transport is examined over the upper 150 m of the water column at 28-degrees-W, using the Seasonal Response of the Equatorial Atlantic experiment moored current meter data at 0.75-degrees-S, 0.0-degrees, and 0.75-degrees-N and a time domain empirical orthogonal function (EOF) analysis to improve spatial and temporal resolution. Gaussian distributions are fit to the mean volume transports per unit width and the fluctuations about these means that are found to be represented by a single EOF mode. The mean volume transport is distributed symmetrically both about the equator and about 75 m depth, with a meridional scale width of …

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15N/14N And 13C/12C In Weddell Sea Birds, Seals, And Fish: Implications For Diet And Trophic Structure, Greg H. Rau, David G. Ainley, John L. Bengston, Joseph J. Torres, Thomas L. Hopkins Jul 1992

15N/14N And 13C/12C In Weddell Sea Birds, Seals, And Fish: Implications For Diet And Trophic Structure, Greg H. Rau, David G. Ainley, John L. Bengston, Joseph J. Torres, Thomas L. Hopkins

Marine Science Faculty Publications

delta-C-13, delta-N-15, and C/N were measured for each of 247 muscle tissue samples from 12 bird, 4 seal, and 4 fish species collected in the Weddell Sea primarily during March 1986. delta-C-13 values ranged from -31.3 to -22.0 parts per thousand and, in the case of fish and seal samples, varied inversely with C/N. This implied that lipid concentration significantly influenced these vertebrate delta-C-13 measurements. No such relationship was found between C/N and delta-N-15, where the latter values ranged from +4.4 to +11.2 parts per thousand. with considerable overlap among many of the taxonomic groups measured. Notable exceptions to this …

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The 26‐Day Oscillation Observed In The Satellite Sea Surface Temperature Measurements In The Equatorial Western Indian Ocean, Pedro T. H. Tsai, James J. O'Brien, Mark E. Luther Jun 1992

The 26‐Day Oscillation Observed In The Satellite Sea Surface Temperature Measurements In The Equatorial Western Indian Ocean, Pedro T. H. Tsai, James J. O'Brien, Mark E. Luther

Marine Science Faculty Publications

A 26‐day oscillation in sea surface temperature (SST) data is observed in the western Indian Ocean, from 52° to 60°E and in the vicinity of the equator. The SST data used in this study are obtained from the NOAA 9 satellite and are for the years 1987 and 1988. This fluctuation of SST at a period near 26 days is found to be antisymmetric about the equator and is trapped within the equatorial waveguide (equator ±6°). The variance associated with this oscillation has a maximum located at about 3° latitude; furthermore, the variance decreases at a faster rate toward the …

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Simulation Of The 1979 Spring Bloom In The Mid-Atlantic Bight: A Coupled Physical/Biological/Optical Model, Watson W. Gregg, John J. Walsh Apr 1992

Simulation Of The 1979 Spring Bloom In The Mid-Atlantic Bight: A Coupled Physical/Biological/Optical Model, Watson W. Gregg, John J. Walsh

Marine Science Faculty Publications

A coupled physical/biological/optical model was developed to investigate the causes of phytoplankton variability in the spring 1979 Mid-Atlantic Bight (MAB) as observed in Coastal Zone Color Scanner (CZCS) imagery, and to estimate the magnitude and variability of primary production. The model incorporated advection, mixing, sinking, growth as a function of light, temperature, and nutrient availability, and death as a function of ingestion. These variables were assumed to determine the large-scale, low-frequency variability of phytoplankton distributions the model also contained two phytoplankton groups, netplankton and nanoplankton, which differed in maximum growth rate, sinking rate, and specific light absorption. The model produced …

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Nutrient Provinces In The Sea: Concentration Ratios, Reaction Rate Ratios, And Ideal Covariation, Kent A. Fanning Apr 1992

Nutrient Provinces In The Sea: Concentration Ratios, Reaction Rate Ratios, And Ideal Covariation, Kent A. Fanning

Marine Science Faculty Publications

Global distributions of the ratios of the concentrations of nitrate + nitrite (= [N]) and phosphate (= [P]) are evaluated from Geochemical Ocean Sections Study (GEOSECS) and Transient Tracers in the Ocean (TTO) data sets. If large oceanic regions (or provinces) can be identified on the basis of constant [N]:[P] ratios, then the distribution equation for a reactive variable shows that the ratio of the net reaction rates involving N and P in each one is equal to its concentration ratio. Organisms within the interiors of the provinces would then be in balance with the ratios in which the nutrients …

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Concentration Of Microbial Populations From Aquatic Environments By Vortex Flow Filtration, Sunny C. Jiang, Jennifer M. Thurmond, Scott L. Pichard, John H. Paul Feb 1992

Concentration Of Microbial Populations From Aquatic Environments By Vortex Flow Filtration, Sunny C. Jiang, Jennifer M. Thurmond, Scott L. Pichard, John H. Paul

Marine Science Faculty Publications

Vortex Flow Filtration was used to concentrate particulate DNA, chlorophyll a and bacteria from freshwater, estuarine, coastal and oligotrophic marine environments. A Membrex Benchmark System with either a 100 kD or a 0.45-mu-m filter and a large-scale Pacesetter System with a 100 kD filter were used. The Benchmark System is ideal for processing 100 ml to 50 l of water, while the Pacesetter is designed for working with volumes from 20 l up to hundreds of liters. The Benchmark System with a 100 kD filter yielded an average recovery of 81.7, 83.3 and 80.5% respectively for particulate DNA, chlorophyll a …

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Reflectance Model For Quantifying Chlorophyll-A In The Presence Of Productivity Degradation Products, Kendall L. Carder, S. K. Hawes, K. A. Baker, R. C. Smith, R. G. Steward, B. G. Mitchell Nov 1991

Reflectance Model For Quantifying Chlorophyll-A In The Presence Of Productivity Degradation Products, Kendall L. Carder, S. K. Hawes, K. A. Baker, R. C. Smith, R. G. Steward, B. G. Mitchell

Marine Science Faculty Publications

Marine colored dissolved organic matter (CDOM) (also gilvin or yellow substance) absorbs light at an exponentially decreasing rate as a function of wavelength. From 410 nm to about 640 nm, particulate phytoplankton degradation products including pheopigments, detritus, and bacteria have absorption curves that are similar in shape to that of CDOM. In coastal areas and areas downstream from upwelling regions, these constituents of seawater often absorb much more light than do living phytoplankton, leading to errors in satellite-derived chlorophyll estimates as high as 133%. Proposed NASA sensors for the 1990s will have spectral channels as low as 412 nm, permitting …

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The Phytoplankton Bloom In The Northwestern Arabian Sea During The Southwest Monsoon Of 1979, John C. Brock, Charles R. Mcclain, Mark E. Luther, William W. Hay Nov 1991

The Phytoplankton Bloom In The Northwestern Arabian Sea During The Southwest Monsoon Of 1979, John C. Brock, Charles R. Mcclain, Mark E. Luther, William W. Hay

Marine Science Faculty Publications

The biological variability of the northwestern Arabian Sea during the 1979 southwest monsoon has been investigated by the synthesis of satellite ocean color remote sensing with analysis of in situ hydrographic and meteorological data sets and the results of wind-driven modeling of upper ocean circulation. The phytoplankton bloom in the northwestern Arabian Sea peaked during August-September, extended from the Oman coast to about 65-degrees-E, and lagged the development of open-sea upwelling by at least 1 month. In total, the pigment distributions, hydrographic data, and model results all suggest that the bloom was driven by spatially distinct upward nutrient fluxes to …

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15N/14N And 13C/12C In Weddell Sea Invertebrates: Implications For Feeding Diversity, Greg H. Rau, Thomas L. Hopkins, Joseph J. Torres Oct 1991

15N/14N And 13C/12C In Weddell Sea Invertebrates: Implications For Feeding Diversity, Greg H. Rau, Thomas L. Hopkins, Joseph J. Torres

Marine Science Faculty Publications

Biomass delta-C-13, delta-N-15, and C/N were measured for each of 29 taxa of pelagic invertebrates sampled from the Weddell Sea in March 1986. The delta-C-13 values of these animals ranged from -33.2 to -23.9 parts per thousand, and a significant negative logarithmic relationship was observed between these values and biomass C/N. This implies that the relative proportion of carbon-rich C-13-depleted lipid in these animals significantly influenced the delta-C-13 of their bulk biomass. No such relationship with C/N is evident with respect to biomass delta-N-15 where values ranged from -1.2 to +7.3 parts per thousand. This spread of values reflects a …

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On The Seasonal Phytoplankton Concentration And Sea Surface Temperature Cycles Of The Gulf Of Mexico As Determined By Satellites, Frank E. Muller-Karger, John J. Walsh, Robert H. Evans, Mark B. Meyers Jul 1991

On The Seasonal Phytoplankton Concentration And Sea Surface Temperature Cycles Of The Gulf Of Mexico As Determined By Satellites, Frank E. Muller-Karger, John J. Walsh, Robert H. Evans, Mark B. Meyers

Marine Science Faculty Publications

Monthly climatologies of near‐surface phytoplankton pigment concentration and sea surface temperature (SST) were derived for the Gulf of Mexico from multiyear series of coastal zone color scanner (CZCS) (November 1978 to November 1985) and advanced very high resolution radiometer (AVHRR) (January 1983 to December 1987) images. We complement these series with SST from the comprehensive ocean‐atmosphere data set (1946–1987) and Climate Analysis Center (1982–1990), and hydrographic profile data from the NOAA National Oceanographic Data Center (1914–1985). The CZCS ocean color satellite data provide the first climatological time series of phytoplankton concentration for the region. The CZCS images show that seasonal …

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Tectonic Evolution Of The Easter Microplate, David F. Naar, R. N. Hey Jan 1991

Tectonic Evolution Of The Easter Microplate, David F. Naar, R. N. Hey

Marine Science Faculty Publications

The plate tectonic history of the Easter microplate has been reconstructed by “closing” the microplate in a series of steps using the Pacific-Nazca magnetic anomalies north and south of the microplate and the NUVEL 1 global plate motion model. After each step, the Easter microplate was rotated rigidly to match the Nazca and Pacific anomalies. Gaps and overlaps formed by this kinematic treatment indicate compressional and tensional deformation, respectively, and show that rigid plate motions are insufficient to explain the complete tectonic evolution. Analysis of the magnetic anomaly data was guided by contoured SeaMARC II, Sea Beam, and 3.5-kHz bathymetry …

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The Seasonal Circulation Of The Upper Ocean In The Bay Of Bengal, James T. Potemra, Mark E. Luther Jan 1991

The Seasonal Circulation Of The Upper Ocean In The Bay Of Bengal, James T. Potemra, Mark E. Luther

Marine Science Faculty Publications

Analysis of the results of a multilayer, adiabatic, numerical model of the upper Indian Ocean, driven by climatological monthly mean winds, shows that the simulated currents in the northeastern Indian Ocean are in general agreement with available observations and interpretations. The main features of the ocean currents include large anticyclonic flow in the Bay of Bengal surface waters during the northern hemisphere winter. This gyre decays into eddies in spring and then transitions into a weaker, cyclonic gyre by late summer. The western recirculation region of this flow is an intensified western boundary current which changes direction twice during the …

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On The Annual Cycle Of Equatorial Upwelling In The Central Atlantic-Ocean, Thomas J. Weingartner, Robert H. Weisberg Jan 1991

On The Annual Cycle Of Equatorial Upwelling In The Central Atlantic-Ocean, Thomas J. Weingartner, Robert H. Weisberg

Marine Science Faculty Publications

The annual cycle of the upper ocean's vertical velocity component (w) on the equator at 28°W is examined by integrating the continuity equation using current meter data from the Seasonal Response of the Equatorial Atlantic Experiment. The annual cycle consists in part of an intense, but brief (∼1 month), upwelling season beginning with the onset of strong easterly wind stress in boreal spring. This upwelling is followed by weaker downwelling during the summer despite the persistence of strong easterly wind stress. The record-length averaged w profile shows that maximum upwelling (0.6 x 10-3cm s-1) …

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A Description Of The Annual Cycle In Sea Surface Temperature And Upper Ocean Heat In The Equatorial Atlantic, Thomas J. Weingartner, Robert H. Weisberg Jan 1991

A Description Of The Annual Cycle In Sea Surface Temperature And Upper Ocean Heat In The Equatorial Atlantic, Thomas J. Weingartner, Robert H. Weisberg

Marine Science Faculty Publications

Temperature and velocity time series, obtained by surface moorings during the Seasonal Response of the Equatorial Atlantic Experiment, are used to investigate the role of ocean dynamics upon the annual cycle of equatorial sea surface temperature (SST) and upper ocean heat. The annual cycle in SST is explained by different mechanisms, each operant at different phases of the cycle. The boreal springtime decrease in SST results from upwelling in response to the seasonal intensification of easterly wind stress. This upwelling causes the seasonal formation of the cold tongue along the equator in the central and eastern portions of the basin. …

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A Linear Analysis Of Equatorial Atlantic Ocean Thermocline Variability, Robert H. Weisberg, T. Y. Tang Dec 1990

A Linear Analysis Of Equatorial Atlantic Ocean Thermocline Variability, Robert H. Weisberg, T. Y. Tang

Marine Science Faculty Publications

Observed variations in the Atlantic Ocean's equatorial thermocline are compared at four locations with simultations using an analytical reduced-gravity model. The comparison shows the essential features of the seasonal wind-forced thermocline response to be accounted for by a linear superposition of equatorial long waves, evolving basinwide, tending to bring the zonal pressure gradient into balance with the wind stress. A frequency response function is derived whose properties provide a basis for discussing the large scale features of the equatorial Atlantic Ocean's seasonal cycle-for example, its evolution along the equator, the maximum upwelling region observed in the Gulf of Guinea and …

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Interannual Differences Of Geosat Altimeter Heights And Sea Level: The Importance Of A Datum, Klaus Wyrtki, Gary Mitchum Jan 1990

Interannual Differences Of Geosat Altimeter Heights And Sea Level: The Importance Of A Datum, Klaus Wyrtki, Gary Mitchum

Marine Science Faculty Publications

Sea surface height data from the Geosat altimeter are compared with island sea level data from 18 gauges in the western and central tropical Pacific during December 1986 to November 1987. Care was taken to ensure that the two data sets are referenced to the same mean surface. This was done by requiring that both data sets have a zero mean sea level over the period April 1985 to April 1986. When the annual means are computed at each station in the later time period, we find that the annual mean sea surface height values have drifted away from the …

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Variability In Upwelling Fields In The Northwestern Indian Ocean 2. Data‐Model Comparison At 9000 Years B.P., Warren L. Prell, Rebecca E. Marvil, Mark E. Luther Jan 1990

Variability In Upwelling Fields In The Northwestern Indian Ocean 2. Data‐Model Comparison At 9000 Years B.P., Warren L. Prell, Rebecca E. Marvil, Mark E. Luther

Marine Science Faculty Publications

Theoretical investigations, in the form of general circulation model (GCM) simulations and empirical studies of pollen, lake levels, and marine sediments suggest that the Indian summer monsoon was intensified 9000 years ago, at a time of increased summer radiation (about 8%) in the northern hemisphere. The southwesterly summer monsoon winds and their pattern of wind stress curl cause coastal upwelling along the coast of Arabia. Stronger summer winds, therefore, should intensify coastal upwelling. Incorporation of the broad‐scale GCM winds into a high‐resolution ocean model of the Arabian Sea produces distinct patterns of stronger upwelling at 9000 years B.P. To verify …

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Variability In Upwelling Fields In The Northwestern Indian Ocean 1. Model Experiments For The Past 18,000 Years, Mark E. Luther Jan 1990

Variability In Upwelling Fields In The Northwestern Indian Ocean 1. Model Experiments For The Past 18,000 Years, Mark E. Luther

Marine Science Faculty Publications

A nonlinear reduced gravity ocean model is used to assess the effects of changes in the monsoon winds during glacial and interglacial conditions on the seasonal circulation in the northwestern Indian Ocean. Winds from the National Center for Atmospheric Research Community Climate Model simulations for 18 kyr B.P. (the most recent glacial maximum and a period of weaker monsoon winds), 9 kyr B.P. (near the beginning of the present interglacial and a period of stronger monsoon winds), and present‐day (0 kyr B.P.) conditions are used to drive the model to a steady seasonal cycle. Strength of upwelling fields are inferred …

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Effect Of Rotation On Vertical Mixing And Associated Turbulence In Stratified Fluids, L. H. Kantha, A. Rosati, B. Galperin Jan 1989

Effect Of Rotation On Vertical Mixing And Associated Turbulence In Stratified Fluids, L. H. Kantha, A. Rosati, B. Galperin

Marine Science Faculty Publications

Combined effects of stratification and rotation on vertical mixing and the characteristics of associated small-scale turbulence are explored using second-moment closure methodology; the rotational terms in the equations for Reynolds stresses and turbulent heat fluxes are retained, not ignored as in earlier works. Semianalytical results valid for arbitrary values of rotation and stratification are derived by further invoking the local equilibrium limit of closure. Two cases are considered: nonzero vertical rotation and nonzero meridional rotation; the latter case is of more general interest in geophysics because of its potential application to equatorial mixed layers. In both cases the influence of …

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Three-Dimensional Inversion Of The Magnetic Field Over The Easter-Nazca Propagating Rift Near 25°S, 112°25′W, Jean-Christophe Sempere, Jeff Gee, David F. Naar, Richard N. Hey Jan 1989

Three-Dimensional Inversion Of The Magnetic Field Over The Easter-Nazca Propagating Rift Near 25°S, 112°25′W, Jean-Christophe Sempere, Jeff Gee, David F. Naar, Richard N. Hey

Marine Science Faculty Publications

The Easter microplate boundary configuration is being reorganized by rift propagation. A Sea Beam survey of the Easter-Nazca spreading center, which forms the eastern boundary of the microplate, has revealed the presence of a young propagating rift growing northward (Naar and Hey, 1986). The tip of the propagating rift is associated with a high-amplitude positive magnetic anomaly. We have performed a three-dimensional inversion of the magnetic field over the propagating rift tip area. The magnetization solution suggests that the western and eastern pseudofaults strike 014° and 338°, respectively, and converge near the rift tip. These orientations yield a propagation to …

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