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Nutrients And Chlorophyll At The Shelf Break Off The Southeastern United States During The Genesis Of Atlantic Lows Experiment: Winter 1986, L. P. Atkinson, J. L. Miller, T. N. Lee, W. M. Dunstan

CCPO Publications

The outer shelf and upper slope off Charleston, South Carolina, were the site of oceanographic and meteorological measurements during the winter of 1986. The purpose of the study was to test ideas about front formation, heat transport, and stratification during cold air outbreaks. An ancillary part of the study was the observation of nutrients and chlorophyll concentrations. The observations extended across the shelf and sometimes crossed the Gulf Stream front. The results show slightly elevated nitrate concentrations in outer shelf waters (1 - 2 μM NO₃) with chlorophyll concentrations in the 1 - 1.8 μg L^-1 range. …

Measuring The Momentum Of Throughfall Drops And Raindrops, Paul Kimble

Masters Theses & Specialist Projects

The methods previously used to determine the momentum and kinetic energy of throughfall drops in the field do not account for the drop's shape at impact or for the variations of the drop's velocity caused by chaotic air currents. The drop's shape at impact is critical because it influences the drop's measurable momentum, kinetic energy, impact force, and the amount of soil that can be displaced by the falling water drop. Since the momentum and kinetic energy of raindrops and throughfall drops are used as indices of soil particle displacement the most accurate momentum and kinetic energydata would be required …

Drought Continues In Hungary In 1995, Attila Bussay, Csaba Szinell

Drought Network News (1994–2001)

In 1995, Hungary again suffered from serious drought. Fortunately, drought has not extended over the whole country. It is primarily centered in the southeast, a plain area with significant agricultural production.

Meteorological conditions have been the most important factors in the evolution of the drought. The start of 1995 was not ideal; dry conditions during 1994 resulted in poor soil moisture at the beginning of the season. In Figure 1, the water shortage is indicated using the Palmer Drought Severity Index (PDSI), revealing the extraordinarily dry winter conditions in the east.

A Prototype National Drought Alert Strategic Information System For Australia, Ken D. Brook, John O. Carter

Drought Network News (1994–2001)

Defining and categorizing drought in a quantitative and scientific manner are important national issues for Australian state and Commonwealth governments, landholders, and agribusiness. The challenge for modelers of Australia’s grasslands is to integrate biological models, geographic information systems (GIS), satellite imagery, economics, climatology, and visual high-performance computing into an Internet-deliverable application that can provide easily understood monitoring and prediction advice in near real-time— a national drought alert strategic information system.

Although NOAA satellite-derived imagery has been somewhat useful in the broad-scale spatial assessment of green cover, especially the spatial response of vegetation to rainfall events (Smith, 1994; Dudgeon et al., …

Simulation The Shift In Position Of Hinge Lines Between Two, Shallow, Flow-Through Lakes, Mohan J. Khisty

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Groundwater flow between two hypothetical, shallow, flow-through lakes was numerically simulated in steady state and transient conditions for two cases. In the first case the lakes are at identical surface water elevations and in the second case there is a small difference in surface water elevations between them. Simulation results from both cases indicate a direct relation between movement of hinge lines, which indicate changes in the direction of groundwater-lake seepage components, and the seasonal persistence and decline of a groundwater mound that exists between the two lakes. A comparison between steady-state simulation results for both cases indicates that a …

Swath Mapping On The Continental Shelf And Slope: The Eel River Basin, Northern California, John A. Goff, Larry A. Mayer, John E. Hughes Clarke, Lincoln F. Pratson

Affiliate Scholarship

First Paragraph

The STRATAFORM program sponsored by the Office of Naval Research (Nittrouer and Kravitz, 1996, this issue) seeks to understand how sedimentary processes lead to the formation of the stratigraphic sequences on continental margins. A central challenge facing this effort is to understand the transport of sediments in shore-parallel as well as shore-perpendicular directions• Multidimensionality is necessary to describe, for example, the accumulation of sediments from river inputs, the distribution of gullies and canyons on the slope, the meandering of channels, and the structure of slumps and slides.

Effects Of Climate Change On Hypoxia In Coastal Waters: A Doubled Co2 Scenario For The Northern Gulf Of Mexico, Dubravko Justic, Nancy N. Rabalais, R. Eugene Turner

Faculty Publications

Projections of general circulation models suggest that freshwater discharge from the Mississippi River to the coastal ocean will increase 20% if atmospheric CO2 concentration doubles. This result is likely to affect water column stability, surface productivity, and global oxygen cycling in the northern Gulf of Mexico, which is the site of the largest (up to 16,500 km2) and most severe hypoxic zone (liter‒1) in the western Atlantic Ocean. We use a coupled physical-biological two-box model to investigate potential effects of climate change on seasonal oxygen cycling and hypoxia in river-dominated coastal waters. The model was developed and calibrated using comprehensive …

Port Everglades Macroinvertebrate Monitoring: Monitoring Of Benthic Macroinvertebrate Assemblages At The Southport Turning Basin And Adjacent Areas Of John U. Lloyd State Recreation Area: January 1996, Charles G. Messing, Richard E. Dodge

Marine & Environmental Sciences Faculty Reports

This report documents the January 1996 monitoring of benthic macroinvertebrate assemblages in the Port Everglades Southport turning basin vicinity and adjacent areas of John U. Lloyd State Recreation Area. This is the eighth monitoring effort of the series carried out by Nova Southeastern University Oceanographic Center. Collections were made between 17 and 31 January 1996.

Modeling Of The Processing And Removal Of Trace Gas And Aerosol Species By Arctic Radiation Fogs And Comparison With Measurements, M H. Bergin, S N. Pandis, C Davidson, J L. Jaffrezo, Jack E. Dibb, A G. Russell, H D. Kuhns

Earth Sciences

A Lagrangian radiation fog model is applied to a fog event at Summit, Greenland. The model simulates the formation and dissipation of fog. Included in the model are detailed gas and aqueous phase chemistry, and deposition of chemical species with fog droplets. Model predictions of the gas phase concentrations of H₂O₂, HCOOH, SO₂, and HNO₃ as well as the fog fluxes of S(VI), N(V), H₂O₂, and water are compared with measurements. The predicted fluxes of S(VI), N(V), H₂O₂, and fog water generally agree with measured …

Influence Of Rice Production On The Quality Of Water In Tailwater Collection Reservoirs, R. A. Dewell, T. L. Lavy

Arkansas Water Resources Center Technical Reports

Since maintaining high water quality standards in the state remains a high priority, monitoring for pesticides in water sources must continue. Determining the type, concentration, and characteristics of any pesticides present in water supplies are essential to the overall assessment of water quality. Five independent locations, implementing contained water management systems and recyclable water, were monitored in 1995 and 1996. Irrigation, runoff, and pond water samples were collected every 10 to 14 days between permanent flood establishment and draining. Water samples were transported to the laboratory and extracted for 16 pesticides using solid phase extraction (SPE) techniques. Quantification and confirmation …

Effects Of Zebra, Mussel, Dreissena Polymorpha Infestation On Lake Dardanelle Water Quality, Charles J. Gagen, Joseph N. Stoeckel

Arkansas Water Resources Center Technical Reports

Zebra mussels recently invaded southern waterways including the Arkansas River. Large-scale filtration of suspended particulate matter by dense populations could alter reservoir ecosystem function. Furthermore, they attach to hard surfaces, thereby threatening normal operations of artificial structures. We designed this study to provide baseline data prior to establishment of high population levels of zebra mussels in Lake Dardanelle. The characterization of spatial and temporal variability in water quality, zooplankton, phytoplankton, and macrophytes will allow testing of several hypotheses. We sampled zebra mussel veliger and settling juvenile densities and zooplankton densities at four fixed sites and the key water quality variables …

Bioaccumulation Of Methyl Mercury Through A Food Chain, J. T. Knight

Arkansas Water Resources Center Technical Reports

The bioaccumulation of mercury through the food chain has received much attention in Arkansas during the last three years. The discovery of mercury contamination and subsequent fish consumption advisories in southwest Arkansas have increased public awareness of the potential for bioaccumulation of different toxic compounds. It is postulated that the mercury problem in Arkansas is a result of methylation and resulting bioaccumulation of mercury as methyl mercury. This study was designed to derive a Bioaccumulation Factor (BAF) for mercury in a simple food chain under controlled conditions. A BAF is calculated by dividing the concentration found in the organism by …

Changes In Drought Policies In New Zealand, Heather J. Keen, Lynmore Rotorua

Drought Network News (1994–2001)

New Zealand, lying in the South Pacific Ocean approximately 1,200 miles east of Australia, is subject to recurring droughts. Its two main islands are long and narrow, with high mountain ranges and hill country bisecting them from north to south. The predominant westerly winds, along with the mountain ranges and hill country, produce a marked orographic effect. Thus, the western side of the country, in general, records significantly higher annual average rainfall totals than does land on the eastern side.

The country has experienced a number of severe droughts throughout its history, especially in the east, where a number of …

Nutrient Changes In The Mississippi River And System Responses On The Adjacent Continental Shelf, Nancy N. Rabalais, R. Eugene Turner, Dubravko Justic, Quay Dortch, William J. Wiseman, Barun Sen Gupta

Faculty Publications

The Mississippi River system ranks among the world's top 10 rivers in freshwater and sediment inputs to the coastal ocean. The river contributes 90% of the freshwater loading to the Gulf of Mexico, and terminates amidst one of the United States' most productive fisheries regions and the location of the largest zone of hypoxia, in the western Atlantic Ocean. Significant increases in riverine nutrient concentrations and loadings of nitrate and phosphorus and decreases in silicate have occurred this century, and have accelerated since 1950. Consequently, major alterations have occurred in the probable nutrient limitation and overall stoichiometric nutrient balance in …

Recent Advances In Seasonal Forecasting In Southern Africa, Leonard S. Uganai

Drought Network News (1994–2001)

Climatic uncertainty posed by the looming possibility of unprecedented climatic change is presenting society with new challenges the world over. In recent years, demand for long-range seasonal to interannual climate forecasts has been on the rise as society grapples with climatic risk management in southern Africa. Although more investment is still required to bring weather services in the region to a level advanced enough to handle the emerging complex and economically justified user needs for climatic services and products, some commendable progress has already been made, particularly in providing seasonal forecasts in addition to the other traditional core services and …

Investigation Of Radio Wave Propagation In The Martian Ionosphere Utilizing Hf Sounding Techniques, Robert J. Yowell

Theses and Dissertations

This thesis presents a preliminary design of an ionospheric sounder to be carried aboard one or more of NASA's Mars Surveyor landers. Past Russian and American probes have indicated the existence of an ionosphere, but none of these missions remotely sensed this atmospheric layer from the surface. The rationale for utilizing a surface-based Martian ionospheric sounder is discussed. Based on NASA's choice of launch vehicle and power source, a low-weight, low-powered Chirp sounder using a horizontally-polarized dipole antenna is recommended for the sounder experiment. The sounder experiment should be conducted for at least one Martian year, in order to investigate …

Recent Climate Anomalies And Their Impact On Snow Chemistry At South Pole, 1987 - 1994, Jack E. Dibb, Sallie I. Whitlow

Earth Sciences

Three 2-m deep snowpits sampled at South Pole in 1994 provide detailed (2-cm resolution) profiles of the concentrations of soluble ionic species for the period 1987 - 1994. The most prominent feature is a large concentration spike of SO4 = in snow deposited in 1992 reflecting fallout from the eruptions of Pinatubo and Hudson in 1991. Concentrations of MSA and values of the MSA/(non-sea-salt SO4 =) ratio are elevated for about three years centered on the prominent volcanic signal. These changes appear to be due to the extended 1991 - 1993 El Nino. The overlapping effects of the volcanic eruptions …

Identification Of Optimal Locations For Sampling Ground Water For Pesticides In The Mississippi Delta Region Of Eastern Arkansas, H. S. Lin, H. D. Scott, J. M. Mckimmey

Arkansas Water Resources Center Technical Reports

Concerns about the presence of pesticides in the Mississippi River Valley alluvial aquifer in the Arkansas Delta have generated the need to develop a map of ground water vulnerability for this region comprised of approximately 10 million acres. Based on the availability of digital data and the scale of this study. we used a modified Pesticide DRASTIC model in a GRASS GIS environment to identify areas that were physically more sensitive to pesticide contamination than other areas within the Delta. Spatial distribution of pesticide loading was estimated from pesticide application rates in different crops and crop distribution map interpreted from …

Trace Element Analysis Of Selected Springs In The Virgin River Basin, Mary A. Yelken

UNLV Theses, Dissertations, Professional Papers, and Capstones

Spring water from 23 springs in and near the Virgin River Basin (southwestern Utah, northwestern Arizona, and southeastern Nevada) was collected and analyzed for chemical concentrations. Trace elements and major ion chemistry was used to determine the potential for utilizing water chemistry to provide information on spring water source and flow pathways. Principal Component Analysis (PCA), rare earth element (REE) normalization patterns, and mineral equilibrium modeling (PHREEQE) techniques were used to analyze the data set. Four major spring water groups were displayed by the PCA, based on similarities in water chemistry. The analyses suggest that spring water chemistry is a …

Report Of Significant Findings--Las Vegas Bay/Boulder Basin Investigations, James F. Labounty, Michael Horn, Bureau Of Reclamation

Publications (WR)

Field sampling was carried out between 0830 and 1500 beginning at the confluence of Las Vegas Wash and the Inner Las Vegas Bay. Ten (10) locations were sampled, each in a similar manner. Locations of sampling stations are in line from the Wash-Bay confluence to a point midway between Saddle and Black Islands. In addition, sampling was done at a location midway between Sentinel Island and the base of Fortification Hill, and at the buoy line in front of Hoover Dam. Sampling stations are labeled from LV01, at Wash-Bay confluence, to LV17 at Hoover Dam. A significant data collection point …

Seasonal And Mesoscale Variability In The Distribution Of Antarctic Krill, Euphausia Superba, West Of The Antarctic Peninsula, Cathy Meyer Lascara

OES Theses and Dissertations

Observations collected between November 1991 and September 1993 during four multidisciplinary cruises were analyzed to provide a description of seasonal and mesoscale variability in the distribution and abundance of Antarctic krill, Euphausia superba, within continental shelf waters west of the Antarctic Peninsula and to investigate possible relationships between variability in krill distributions and variability in selected environmental parameters. Acoustic measurements of krill were made each season at designated locations to estimate the abundance of krill, in terms of vertically-integrated krill biomass and the number of aggregations, characterize the depth distribution of krill, and provide a quantitative description of the size, …

Recruitment Of Blue Crab, Callinectes Sapidus, Postlarvae To The Back-Barrier Lagoons Of Virginia's Eastern Shore, Robert D. Brumbaugh

OES Theses and Dissertations

Most research on the early life history of the blue crab, Callinectes sapidus, has been conducted in large partially stratified estuaries such as the Chesapeake Bay. In contrast, little is known about the recruitment dynamics or habitat requirements of blue crab postlarvae (megalopae) in shallow well-mixed lagoonal systems that make up a considerable part of the species' range. In Virginia's coastal lagoons, planktonic blue crab megalopae are most abundant at night on flooding tides, and are not abundant during the daytime or on ebbing tides. This appears to enhance retention within the lagoons, despite the short residence time of water …

Observation Of Shelfwater Overrunning The Southern Slope Sea, Ajoy Kumar

OES Theses and Dissertations

Analyses of two years (1992 and 1993) of high resolution (1.47 km²) sea surface temperature satellite images of the southern Mid-Atlantic Bight (MAB), showed that unusually extensive overhang of shelf water occurs episodically, and coherently over along shelf distances of several hundred kilometers. These episodes are dubbed overrunning of the Slope Sea by shelf water. The overrunning volume has a "face" and a "back" (southern and northern limit). It transports substantial quantities of shelf water southward, and does not retreat onto the shelf, but eventually joins the western edge of the Gulf Stream in the vicinity of Chesapeake …

The Effects Of Environmental Variability On The Population Structure Of The Eastern Oyster (Crassostrea Virginica): A Modeling Study, Margaret Mcmanus Dekshenieks

OES Theses and Dissertations

Three models were coupled to investigate the effects of changes in environmental conditions on the population structure of the Eastern oyster, Crassostrea virginica. The first model, a time-dependent model of the oyster population as described in Powell et al. (1992) and Hofmann et al. (1992, 1995), tracks the distribution, development, spawning, and mortality of sessile oyster populations. The post-settlement model incorporates mortality through parasitism, predation, food depletion and extremes in environmental conditions. The post-settlement model supplies the initial abundance of larvae spawned into the water column, and in turn is the recipient of cohorts of spawn which survive through metamorphosis. …

A One-Dimensional Model For Storm Breaching Of Barrier Islands, Cheol Shik Shin

Civil & Environmental Engineering Theses & Dissertations

A set of numerical models is developed for simulating the four stages of barrier breaching characterized by one horizontal spatial dimension.

The SBEACH model is employed for the first stage of dune/beach erosion. The Lax-Wendroff two-step explicit scheme for Stage II is developed to simulate initiation of ocean flood propagation on initially dry barrier islands and the method of characteristics (MOC), is employed to compute additional boundary data. The development of the Preissmann implicit scheme for water motion and a forward time centered space explicit scheme for sediment motion in Stages III and IV provide a tool to study the …

An Introduction To Lake And Reservoir Water Quality Modeling, Kenneth H. Reckhow

Arkansas Water Resources Center Technical Reports

No abstract provided.

Drought Preparedness And Management Training Seminar Conducted For West Africa

Drought Network News (1994–2001)

All of the World Meteorological Organization (WMO) member countries of western Africa were represented at a seminar conducted in Banjul, The Gambia, 4–9 September 1995. The Training Seminar on Drought Preparedness and Management for Western Africa was conducted to improve awareness of drought and appropriate mitigation and preparedness technologies to reduce impacts. The seminar was organized by WMO and sponsored by WMO and the UN Sudano-Sahelian Office.

Effects Of Water Stress On Soybean Productivity In Central India, Ajay K. Srivastava, Diwakar Naidu, A. S. R. A. S. Sastri, J. S. Urkurkar, B. Das Gupta

Drought Network News (1994–2001)

In the Chhattisgarh plains in the agroclimatic region of central India (Figure 1), farms may be characterized by one of the following: unbunded lathyritic soils, bunded rice fields (rainfed), bunded rice fields (irrigated), unbunded black soils, or rice bunds. Under these five farming situations, different crop sequences have been in vogue. New crops and crop sequences are recommended by the Agricultural University from time to time based on experimental results.

In the unbunded black soils, farmers usually plant small millets and pigeon pea. However, based on experimental results, the University has recommended soybean followed by chickpea crop sequence under rainfed …

Vulnerability Assessment Of Water Resources In Egypt To Climatic Change In The Nile Ba, Kenneth M. Strzepek, David N. Yates, Dia El Din El Quosy

Egypt & Libya

: The impacts of global climate change on the water resources of the Nile River Basin were evaluated using simulation models. Four climate change scenarios were evaluated (baseline, GISS, GFDL, and UKMO). The complete impact of climatic changes in the Nile cannot be fully predicted with confidence, as some models forecast increased flows, while others project significant decreases. How ever, it was observed that the Nile River flow is extremely sensitive to ambient temperature and pre cipitation changes, and it is possible that the effects of climatic fluctuations would be severe. Several water management options were identified to help adapt …

Asian Influence Over The Western North Pacific During The Fall Season: Inferences From Lead 210, Soluble Ionic Species And Ozone, Jack E. Dibb, R. Talbot, Anthony Klemm, G L. Gregory, H B. Singh, J D. Bradshaw, S T. Sandholm

Earth Sciences

Aerosol samples collected over the western Pacific during the NASA/Global Tropospheric Experiment Pacific Exploratory Mission (PEM-West A) expedition (September–October 1991) revealed mean ²¹⁰Pb concentrations in the free troposphere in the 5–10 fCi m⁻³ STP range. Most soluble ionic aerosol-associated species were near detection limits [≪40 parts per trillion by volume (pptv)] in these same samples. The altitude distribution of O₃ near Asia closely resembled that of ²¹⁰Pb, while no relationship was found between the concentrations of O₃ and ⁷Be. Free tropospheric air over the western Pacific was depleted in soluble aerosol-associated species but enriched …