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2000

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Articles 91 - 120 of 133

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Use Of Climatology To Predict Maximum Wind Speeds At The Kennedy Space Center And Cape Canaveral Air Station, Lisa K. Coleman Mar 2000

Use Of Climatology To Predict Maximum Wind Speeds At The Kennedy Space Center And Cape Canaveral Air Station, Lisa K. Coleman

Theses and Dissertations

This thesis uses statistical analysis to forecast the probability of meeting or exceeding the maximum allowable wind speeds for each of the launch pads at the Kennedy Space Center (KSC) and Cape Canaveral Air Station (CCAS). Wind data were collected from the Weather Information Network Display System (WINDS), a collection of 47 meteorological towers located throughout KSC and CCAS, over a period of five winters. A Fortran program was written to calculate conditional probabilities of meeting or exceeding a given threshold speed during eight consecutive one-hour periods, using the current wind direction and peak wind speed as inputs. Forecast probabilities …


Data Warehouse Techniques To Support Global On-Demand Weather Forecast Metrics, Meriellen C. Joga Mar 2000

Data Warehouse Techniques To Support Global On-Demand Weather Forecast Metrics, Meriellen C. Joga

Theses and Dissertations

Air Force pilots and other operators make crucial mission planning decisions based on weather forecasts; therefore, the ability to forecast the weather accurately is a critical issue to Air Force Weather (AFW) and its customers. The goal of this research is to provide Air Force Weather with a methodology to automate statistical data analysis for the purpose of providing on-demand metrics. A data warehousing methodology is developed and applied to the weather metrics problem in order to present an option that will facilitate on-demand metrics. On-line analytical processing (OLAP) and data mining solutions are also discussed.


An Intelligent User Interface To Support Air Force Weather Product Generation And Automated Metrics, Darryl N. Leon Mar 2000

An Intelligent User Interface To Support Air Force Weather Product Generation And Automated Metrics, Darryl N. Leon

Theses and Dissertations

Air Force pilots require dependable weather reports so they may avoid unsafe flying conditions. In order to better gauge the accuracy of its weather products, Air Force Weather has established the requirement for an Air Force-wide automated weather metrics program. Under the guidelines for this program, forecasts will automatically be compared to observed weather to determine their accuracy. Statistics will be collected in the hopes of determining forecast error trends that can be corrected through education and training. In order for the statistical data produced by such a program to draw reliable conclusions about forecast accuracy, however, the correct format …


Mixed Layer Height Estimates – A Statistical Analysis Of Algorithm Performance, Lisa C. Shoemaker Mar 2000

Mixed Layer Height Estimates – A Statistical Analysis Of Algorithm Performance, Lisa C. Shoemaker

Theses and Dissertations

The Air Force Technical Applications Center (AFTAC) conducts dispersion transport modeling as part of their mission support for the United States Atomic Energy Detection System. Part of that modeling effort requires knowledge of the height of the mixed layer in the lower atmosphere to determine the vertical extent through which particulates can be distributed. The mixed layer can be estimated by analyzing atmospheric profiles of parameters obtained from observations (e.g., upper air soundings) or atmospheric models. Six mixed layer algorithms were evaluated: Gradient Richardson Number (RICH), Potential Temperature (POTEMP), Potential Instability Mixing Depth (PIMIX), and three variations of the PIMIX …


Composition And Distribution Of Aerosols Over The North Atlantic During The Subsonic Assessment Ozone And Nitrogen Oxide Experiment (Sonex), Jack E. Dibb, R. Talbot, Eric Scheuer Feb 2000

Composition And Distribution Of Aerosols Over The North Atlantic During The Subsonic Assessment Ozone And Nitrogen Oxide Experiment (Sonex), Jack E. Dibb, R. Talbot, Eric Scheuer

Earth Sciences

We report the mixing ratios of aerosol-associated soluble ions (focusing on SO4= and NO3) and HNO3 over the North Atlantic during NASA's Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX). The SONEX campaign was designed to quantify the impacts of jet emissions in the North Atlantic Flight Corridor (NAFC) by sampling both directly within and far removed from the organized track system. Beryllium-7 activities were also measured to assess the magnitude of stratospheric influence in the SONEX study region. Mixing ratios of aerosol-associated SO4= and NO3 above 8 km during …


Crop Updates 2000 Cereals - Part 3, Roslyn J. Jettner, Blakely Paynter, Glenn Macdonald, Pierre Fievez, Ian Foster, David Tennant, Wal Anderson, James Ridsdill-Smith, Celia Pavri, Ross Chapman, Senthold Asseng, Steve Carr, Brad Nutt, Lindrea Latham, Roger Jones, Anyou Liu, Clinton K. Revell, David Ferris, Roy Latta, Lisa-Jane Blacklow, Chris Matthews, Ted Woodburn, Paul Yeoh, Ian Rose, Anita Lyons, Simon Cook, Matthew L. Adams, Robert J. Corner Feb 2000

Crop Updates 2000 Cereals - Part 3, Roslyn J. Jettner, Blakely Paynter, Glenn Macdonald, Pierre Fievez, Ian Foster, David Tennant, Wal Anderson, James Ridsdill-Smith, Celia Pavri, Ross Chapman, Senthold Asseng, Steve Carr, Brad Nutt, Lindrea Latham, Roger Jones, Anyou Liu, Clinton K. Revell, David Ferris, Roy Latta, Lisa-Jane Blacklow, Chris Matthews, Ted Woodburn, Paul Yeoh, Ian Rose, Anita Lyons, Simon Cook, Matthew L. Adams, Robert J. Corner

Crop Updates

This session covers eighteen papers from different authors:

BARLEY AND OAT AGRONOMY

1. Unicorn barley must meet malting specifications to be a viable option, Roslyn Jettnerand Blakely Paynter, Agriculture Western Australia

2. Optimum oat seed rates, Glenn McDonald, Agriculture Western Australia

3. Production and Quality of export Oaten Hay (1998 and 1989), Pierre Fievez, Pierre Fievez and Associates

FROST

4. Climatology of Frost in Southern Western Australia, Ian Foster, Agriculture Western Australia

5. Flowering calculator, David Tennant, Agriculture Western Australia

6. Some options for managing the risk of frost damage, Wal Anderson, Agriculture Western Australia

PASTURE

7. …


Horizontal Structure Of The Upper Ocean Velocity And Density Fields In The Western Equatorial Pacific Warm Pool: Depth Range From 20 To 250 M, Alexander Soloviev, Roger Lukas, Peter Hacker Feb 2000

Horizontal Structure Of The Upper Ocean Velocity And Density Fields In The Western Equatorial Pacific Warm Pool: Depth Range From 20 To 250 M, Alexander Soloviev, Roger Lukas, Peter Hacker

Marine & Environmental Sciences Faculty Articles

Wavenumber spectra of velocity and density fields in the western equatorial Pacific warm pool on scales 6–120 km are estimated using the shipboard survey data collected during the TOGA Coupled Ocean–Atmosphere Response Experiment (COARE). The spectra are averaged over three depth intervals: 20–60, 60–110, and 110–250 m (corresponding to the Yoshida jet, the South Equatorial Current, and the southern edge of Equatorial Undercurrent). The velocity spectra are corrected for the mean flow shear advection, which is important under conditions of low gradient Richardson number (Ri). After that, both velocity and density spectra are consistent with an internal wave spectral model …


Sea Turtle Conservation Program, Broward County, Fl 2000 Report, Curtis M. Burney, William E. Margolis Jan 2000

Sea Turtle Conservation Program, Broward County, Fl 2000 Report, Curtis M. Burney, William E. Margolis

Marine & Environmental Sciences Faculty Reports

No abstract provided.


Study Abroad M.S. Degree In Marine Biology, Nova Southeastern University Jan 2000

Study Abroad M.S. Degree In Marine Biology, Nova Southeastern University

Halmos College of Natural Sciences and Oceanography Course Catalogs

No abstract provided.


Water Resources Issues In The Arkansas Delta, Kenneth F. Steele Jan 2000

Water Resources Issues In The Arkansas Delta, Kenneth F. Steele

Arkansas Water Resources Center Technical Reports

Despite its location in Northwest Arkansas, the Arkansas Water Resources Center (AWRC) is active state-wide. This fact is underscored by the focus of the Center’s session on "Water Resource Issues in the Arkansas Delta" during its recent joint Conference. Water issues in the Delta include declining water tables, salt water intrusion, and water quality (especially suspended sediment, nitrate and pesticides). Presented papers focused on best management practices for cotton production, economics of on-farm reservoirs, chloride content of irrigation water, and landowner education. The AWRC short course was an excellent one on chemical transport in the vadose zone by Dr. Glenn …


Success And Growth Of Corals Transplanted To Cement Armor Mat Tiles In Southeast Florida: Implications For Reef Restoration, S. L. Thornton, Richard E. Dodge, David S. Gilliam, R. Devictor, P. Cooke Jan 2000

Success And Growth Of Corals Transplanted To Cement Armor Mat Tiles In Southeast Florida: Implications For Reef Restoration, S. L. Thornton, Richard E. Dodge, David S. Gilliam, R. Devictor, P. Cooke

Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

In 1997, 271 scleractinian corals growing on a sewer outfall pipe were used in a transplantation study offshore from North Dade County, Florida, USA. Corals were removed from the outfall pipe and transplanted onto concrete armor mat tiles used to cover the pipe. Success (number of corals still attached and alive), mortality (number of dead corals), and growth rates of the transplants were assessed between December 1997 and December 1999. Colony surface area and radius length were measured on scanned photographs to estimate horizontal growth rate. After two years post-transplantation, success rate and overall mortality were 87% and 7.8% respectively. …


Reefs And Coral Carpets In The Miocene Paratethys (Badenian, Leitha Limestone, Austria), Bernhard Riegl, W. E. Piller Jan 2000

Reefs And Coral Carpets In The Miocene Paratethys (Badenian, Leitha Limestone, Austria), Bernhard Riegl, W. E. Piller

Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

Biohermal (reefs) and biostromal (coral carpets) facies were studied in the Austrian Middle Miocene Leitha Limestone. In the Vienna Basin ("Fenk quarry") non-framebuilding and framebuilding biostromal coral communities were found. In the Styrian Basin, well developed patch reefs were observed besides coral carpets. In the Fenk quarry, 2 coral carpet types, four non-framework coral communities, and one bivalve/coral community were found. In "Retznei quarry" (Styrian Basin) patch reefs, basal corallinacean calcarenites were followed by a Ponies layer capped by marl, and the main reef-building higher diversity phase dominated by faviids ( Montastraea, Tarbellastraea). In the "Tittenbacher quarry" no internal …


Skeletal Architecture And Density Banding In Diploria Strigosa By X-Ray Computed Tomography, Kevin P. Helmle, Richard E. Dodge, R. A. Ketcham Jan 2000

Skeletal Architecture And Density Banding In Diploria Strigosa By X-Ray Computed Tomography, Kevin P. Helmle, Richard E. Dodge, R. A. Ketcham

Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

Density bands in corals have long been considered a valuable tool for reconstructing past environmental and climatic conditions. X-radiographs reveal density banding within a skeletal slab, but provide little information about the skeletal variability causing banding. The skeletal architecture of Diploria strigosa was analyzed by X-radiography, X-ray computed tomography, and image analysis to identify the specific skeletal elements responsible for density banding. Threedimensional skeletal reconstructions, density-band reconstructions, and skeletal animations were created to assess the apparent changes in skeletal structure associated with density banding. Measurements were made of the dissepiments, thecae, septa, and columellae to determine how element size related …


The Marine Fishes Of Broward County, Florida Report Of 1999-2000 Survey Results Noaa/Nmfs Order # 40genf900158, Richard E. Spieler Jan 2000

The Marine Fishes Of Broward County, Florida Report Of 1999-2000 Survey Results Noaa/Nmfs Order # 40genf900158, Richard E. Spieler

Marine & Environmental Sciences Faculty Reports

No abstract provided.


Acth4 -10, Substance P, And Dizolcipine (Mk-801) Accelerate Functional Recovery After Hemilabyrinthectomy In Goldfish, Rosana Mattioli, Joseph P. Huston, Richard E. Spieler Jan 2000

Acth4 -10, Substance P, And Dizolcipine (Mk-801) Accelerate Functional Recovery After Hemilabyrinthectomy In Goldfish, Rosana Mattioli, Joseph P. Huston, Richard E. Spieler

Marine & Environmental Sciences Faculty Articles

In this study, we evaluated the goldfish model of hemilabyrinthectomy for investigating potential recovery-promoting drugs. In this lesion model, the unilateral removal of the labyrinth induces a postural imbalance in response to light (Dorsal Light Reflex), from which the animals can recover over time. The behavioral effects of two neuropeptides were tested–namely, of substance P and ACTH4-10, both of which are known to promote functional recovery in several other lesion models. Furthermore, the effect of MK- 801, an antagonist of the glutamatergic NMDAreceptor subtype, was tested because this substance has also been shown to exert a neuroprotective effect. After lesion …


The Linkage Between Upper Circumpolar Deep Water (Ucdw) And Phytoplankton Assemblages On The West Antarctic Peninsula Continental Shelf, Barbara B. Prézelin, Eileen E. Hofmann, Claudia Mengelt, John M. Klinck Jan 2000

The Linkage Between Upper Circumpolar Deep Water (Ucdw) And Phytoplankton Assemblages On The West Antarctic Peninsula Continental Shelf, Barbara B. Prézelin, Eileen E. Hofmann, Claudia Mengelt, John M. Klinck

OES Faculty Publications

Intrusion of Upper Circumpolar Deep Water (UCDW), which was derived from the Antarctic Circumpolar Current (ACC), onto the western Antarctic Peninsula (WAP) shelf region in January 1993 provided a reservoir of nutrient-rich, warmer water below 150 m that subsequently upwelled into the upper water column. Four sites, at which topographically-induced upwelling of UCDW occurred, were identified in a 50 km by 400 km band along the outer WAP continental shelf. One additional site at which wind-driven upwelling occurred was also identified. Diatom-dominated phytoplankton assemblages were always associated with a topographically-induced upwelling site. Such phytoplankton communities were not detected at any …


Biochemical Composition Of Particles And Dissolved Organic Matter Slong An Estuarine Gradient: Sources And Implications For Dom Reactivity, Antonio Mannino, H. Rodger Harvey Jan 2000

Biochemical Composition Of Particles And Dissolved Organic Matter Slong An Estuarine Gradient: Sources And Implications For Dom Reactivity, Antonio Mannino, H. Rodger Harvey

OES Faculty Publications

The chemical composition of high molecular weight dissolved organic matter (DOM) and particulate organic matter (POM) was examined along the salinity gradient of the Delaware Estuary. DOM was collected and fractionated by tangential-flow ultrafiltration into 1-30 kDa (HDOM; high molecular weight) and 30 kDa to 0.2 μm (VHDOM; very high molecular weight) and compared to particles collected in parallel. Polysaccharides comprised 12-43% of particulate organic carbon (POC), 30-56% of VHDOM carbon, and 7.5-19% of HDOM carbon. Hydrolyzable amino acids comprised 17-38% of POC, 5.4-12% of VHDOM carbon, and 1.5-4.2% of HDOM carbon. Only 7-43% of dissolved organic nitrogen in VHDOM …


The Effects Of Light And Nitrate Levels On The Relationship Between Nitrate Reductase Activity And (No3-)-N-15 Uptake: Field Observations In The East China Sea, Chin-Chang Hung, George T. F. Wong, Kom-Kee Liu, Fuh-Kwo Shiah, Gwo-Ching Gong Jan 2000

The Effects Of Light And Nitrate Levels On The Relationship Between Nitrate Reductase Activity And (No3-)-N-15 Uptake: Field Observations In The East China Sea, Chin-Chang Hung, George T. F. Wong, Kom-Kee Liu, Fuh-Kwo Shiah, Gwo-Ching Gong

OES Faculty Publications

Nitrate reductase activity (NRA) and 15NO3- uptake (NU) were determined in the East China Sea and the adjoining Kuroshio in May 1996, at six stations covering a range of hydrographic conditions: the nutrient-rich and fresher plume of Changjiang Diluted Water along the Chinese coast, the nutrient-rich upwelling Kuroshio Subsurface Water at the shelf edge northeast of Taiwan, the oligotrophic Kuroshio Surface Water and the mixing zones among these water masses on the shelf. The values of NRA in the surface mixed layer ranged between 16 and 0.1 nM-N h-1, whereas those of NU ranged between …


Intraspecific Variation In The Selenium Requirement Of Different Geographic Strains Of The Toxic Dinoflagellate Gymnodinium Catenatum, Martina A. Doblin, Susan I. Blackburn, Gustaaf M. Hallegraeff Jan 2000

Intraspecific Variation In The Selenium Requirement Of Different Geographic Strains Of The Toxic Dinoflagellate Gymnodinium Catenatum, Martina A. Doblin, Susan I. Blackburn, Gustaaf M. Hallegraeff

OES Faculty Publications

The requirement for selenium (IV) was assessed in five strains of the toxic dinoflagellate Gymnodinium catenatum Graham, representing three populations from Tasmania (Australia), as well as one each from Japan and Spain. Strains were grown in nutrient-enriched sea water medium with 10-9 M selenium added as selenite (H2SeO3), or with no added selenium, and monitored for growth and cell yield. Strains exhibited different selenium (Se) requirements, as evidenced by (i) a decrease in exponential growth rate (10-20%) and cell yield (up to 80%) (Japanese strain); (ii) a decrease in cell yield only (Tasmania Derwent Estuary …


Iron And Manganese In The Ross Sea, Antarctica: Seasonal Iron Limitation In Antarctic Shelf Waters, Peter N. Sedwick, Giacomo R. Ditullio, Denis J. Mackey Jan 2000

Iron And Manganese In The Ross Sea, Antarctica: Seasonal Iron Limitation In Antarctic Shelf Waters, Peter N. Sedwick, Giacomo R. Ditullio, Denis J. Mackey

OES Faculty Publications

Dissolved iron and manganese and total dissolvable iron were measured in water column samples from the Polynya Region of the southern Ross Sea in cruises in Nov.-Dec. 1994 (spring 1994) and Dec. 1995 to Jan. 1996 (summer 1995). Iron and manganese addition bottle incubation experiments were also performed on these cruises to assess the nutritional sufficiency of ambient iron and manganese concentrations for phytoplankton growth. Generally high dissolved iron concentrations (>0.5 nM) and relatively complex iron and manganese vertical profiles were obtained in spring 1994 vs. summer 1995. Dissolved iron concentrations in the upper water column averaged 1.0 nM …


Soapbox: The Academic Research Fleet: An Exciting Time For Renewal, Larry Atkinson Jan 2000

Soapbox: The Academic Research Fleet: An Exciting Time For Renewal, Larry Atkinson

CCPO Publications

(First Paragraph) Academic research ships in the United States are the envy of many scientists around the world. A great strength of our system is the diversity of ships and operators: users have a choice, the system can change. A weakness of the system is that very diversity: sometimes it is hard for us to act together. Nevertheless, we now must act together. The vitality of the academic fleet in the coming decades is at stake. The reason is simply because many of our ships, especially in the intermediate size range, will soon reach the end of their useful life.


Oxygen Isotopes And Metolachlor Residues In Water Samples From A Portion Of The Canajoharie Creek Watershed, Central New York, John M. Nadeau Jan 2000

Oxygen Isotopes And Metolachlor Residues In Water Samples From A Portion Of The Canajoharie Creek Watershed, Central New York, John M. Nadeau

Geology Theses and Dissertations

Increased ground and surface water contamination has fueled the need for a better understanding of factors affecting hydrogeological settings. Seasonal variability in the recharge of an aquifer can affect the rate and amount of contamination that can occur. Stable isotopes have been previously investigated as tracers to determine flow paths of the water and contaminants. In this study, oxygen isotopes were used to determine the factors that influence seasonal variations in ground and surface water, such as well location, aquifer type, surface water sites, and soil type. Samples were collected from different locations around the Canajoharie Field Site, including wells …


Dating Marine Terraces With Relative-Age And Correlated-Age Methods, Daniel R. Muhs Jan 2000

Dating Marine Terraces With Relative-Age And Correlated-Age Methods, Daniel R. Muhs

United States Geological Survey: Staff Publications

Coastal landforms, and particularly emergent marine terraces, a re amongt he most importantg eomorphicfe aturesi n studieso f Quaternarys eal evel fluctuationsa nd neotectonics. A general model, first articulated by Alexander (1953) and borne out by detailedr ecent studieso n many coastlinesi,s that emergent flights of erosional terraces and coral reefs (Fig. 1) are the resulto f glacioeustaticallyc ontrolledf luctuations of global sea level superimposed on steady uplift. Similiarity of U-series ages of coral from both constructional reefsi n the tropicsa nd erosionalt erracesi n midlatitudesh as provided a rigorous test of this model (Mesolella and others, 1969; Bloom and …


Blending Hf Radar And Model Velocities In Monterey Bay Through Normal Mode Analysis, B. L. Lipphardt Jr., A. D. Kirwan Jr., C. E. Grosch, J. K. Lewis, J. D. Paduan Jan 2000

Blending Hf Radar And Model Velocities In Monterey Bay Through Normal Mode Analysis, B. L. Lipphardt Jr., A. D. Kirwan Jr., C. E. Grosch, J. K. Lewis, J. D. Paduan

CCPO Publications

Nowcasts of the surface velocity field in Monterey Bay are made for the period August 1-9, 1994, using HF radar observations blended with results from a primitive equation model. A spectral method called normal mode analysis was used. Objective spatial and temporal filtering were performed, and stream function, velocity potential, relative vorticity, and horizontal divergence were calculated over the domain. This type of nowcasting permits global spectral analysis of mode amplitudes, calculation of enstrophy, and additional analyses using tools like empirical orthogonal functions. The nowcasts reported here include open boundary flow information from the numerical model. Nowcasts using no open …


On The Seasonal Mixed Layer Simulated By A Basin-Scale Ocean Model And The Mellor-Yamada Turbulence Scheme, Tal Ezer Jan 2000

On The Seasonal Mixed Layer Simulated By A Basin-Scale Ocean Model And The Mellor-Yamada Turbulence Scheme, Tal Ezer

CCPO Publications

Seasonal changes and vertical mixing processes in the upper layers of the North Atlantic Ocean are simulated with a basin-scale sigma coordinate ocean model that uses the Mellor-Yamada turbulence closure scheme. The cause of insufficient surface mixing and a too shallow summertime thermocline, common problems of ocean models of this type, is investigated in detail by performing a series of sensitivity experiments with different surface forcing conditions and different turbulence parameterizations. A recent improvement in the parameterization of the dissipation term in the Mellor-Yamada turbulence scheme, which has shown a significant improvement in one-dimensional calculations, had a positive but relatively …


Can An Optical Plankton Counter Produce Reasonable Estimates Of Zooplankton Abundance And Biovolume In Water With High Detritus?, X. Zhang, M. Roman, A. Sanford, H. Adolf, C. Lascara, R. Burgett Jan 2000

Can An Optical Plankton Counter Produce Reasonable Estimates Of Zooplankton Abundance And Biovolume In Water With High Detritus?, X. Zhang, M. Roman, A. Sanford, H. Adolf, C. Lascara, R. Burgett

CCPO Publications

The Optical Plankton Counter (OPC) has been used in oceanic and fresh waters to estimate zooplankton abundance and biovolume. However, it is not clear whether the OPC can produce accurate estimates of zooplankton abundance and biovolume in waters with high detritus. In order to test the capability of the OPC to estimate zooplankton abundance and biovolume in Chesapeake Bay, two sets of laboratory experiments were conducted using water with high detritus concentrations collected from the upper Choptank estuary of Chesapeake Bay and laboratory cultured Artemia. Our results suggest that the OPC is able to produce accurate estimates of zooplankton biovolume …


On The Sources Of Weddell Gyre Antarctic Bottom Water, Michael P. Meredith, Ricardo A. Locarnini, Kim A. Van Scoy, Andrew J. Watson, Karen J. Heywood, Brian A. King Jan 2000

On The Sources Of Weddell Gyre Antarctic Bottom Water, Michael P. Meredith, Ricardo A. Locarnini, Kim A. Van Scoy, Andrew J. Watson, Karen J. Heywood, Brian A. King

CCPO Publications

In March-April 1995, as part of the World Ocean Circulation Experiment section A23, we completed 49 hydrographic stations across the Weddell Gyre and southern Antarctic Circumpolar Current, from the Antarctic continental shelf (72.5°S, 16.5°W) to South Georgia (55°S, 34.5°W). Chlorofiuorocarbon (CFC11, CFC-12, and CFC-113) data collected at these stations reveal that distinct sources renew the Antarctic Bottom Water (defined as waters with potential temperatures less than 0°C) of the Weddell Gyre. Weddell Sea Bottom Water (defined as waters with potential temperatures less than- 0.7°C) formed in the western Weddell Sea has CFC concentrations about 5 to 6 times higher in …


Physicochemical Characteristics And Macroinvertebrate Assemblages Of Riffles Upstream And Downstream Of A Streambank Impacted By Unrestricted Cattle Access, Ronald L. Johnson, Daniel D. Ward, Richard S. Grippo Jan 2000

Physicochemical Characteristics And Macroinvertebrate Assemblages Of Riffles Upstream And Downstream Of A Streambank Impacted By Unrestricted Cattle Access, Ronald L. Johnson, Daniel D. Ward, Richard S. Grippo

Journal of the Arkansas Academy of Science

Riparian zones are important contributors to stream ecosystem health. Alteration of such areas can change stream structure and function, resulting in modified productivity and hydrologic patterns. We studied two riffle sites on the South Fork of the Spring River in Fulton County, AR upstream and downstream of a streambank ostensibly degraded by unrestricted cattle access. The two sites were measured for differences in physical habitat (including bank width, stream velocity, depth, substrate composition, and embeddedness), chemical characteristics (including dissolved oxygen, pH, conductivity, turbidity and total suspended solids) and biological characteristics (including benthic macroinvertebrate community composition, similarity, and standing crop). Measurements …


Fortnightly Variability In The Transverse Dynamics Of A Coastal Plain Estuary, Arnoldo Valle-Levinson, Kuo-Chuin Wong, Kamazima M. M. Lwiza Jan 2000

Fortnightly Variability In The Transverse Dynamics Of A Coastal Plain Estuary, Arnoldo Valle-Levinson, Kuo-Chuin Wong, Kamazima M. M. Lwiza

CCPO Publications

Current velocity and water density profiles were obtained along two crossestuary transects with the purpose of determining the fortnightly variability of the transverse dynamics in a partially stratified coastal plain estuary. The profiles were measured with a towed acoustic Doppler current profiler and a conductivity-temperaturedepth recorder in the James River estuary, Virginia. The cross-estuary transects were sampled during the spring tides of October 26-27, 1996, and the ensuing neap tides of November 2-3, 1996. The transects were-4 km long, featured a bathymetry that consisted of a channel flanked by shoals, and were sampled repeatedly during two semidiurnal tidal cycles (25 …


Convergence Of Lateral Flow Along A Coastal Plain Estuary, Arnoldo Valle-Levinson, Chunyan Li, Kuo-Chuin Wong, Kamazima M. M. Lwiza Jan 2000

Convergence Of Lateral Flow Along A Coastal Plain Estuary, Arnoldo Valle-Levinson, Chunyan Li, Kuo-Chuin Wong, Kamazima M. M. Lwiza

CCPO Publications

A set of velocity profiles obtained in the James River estuary with an acoustic Doppler current profiler was used in combination with the results of an analytic tidal model to depict the appearance of surface lateral flow convergences (δv/δy) during both flood and ebb stages of the tidal cycle. The bathymetry of the estuary was characterized by a main channel and a secondary channel separated by relatively narrow shoals. Lateral surface flow convergences appeared over the edges of the channels and were produced by the phase lag of the flow in the channel relative to the …