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Assessment Of The Record Of The 1982 El Chichón Eruption As Preserved In Greenland Snow, Gregory A. Zielinski, Jack E. Dibb, Qinzhao Yang, Paul A. Mayewski, Sallie I. Whitlow, Mark S. Twickler, Mark S. Germani Dec 1997

Assessment Of The Record Of The 1982 El Chichón Eruption As Preserved In Greenland Snow, Gregory A. Zielinski, Jack E. Dibb, Qinzhao Yang, Paul A. Mayewski, Sallie I. Whitlow, Mark S. Twickler, Mark S. Germani

Earth Sciences

Variability in the SO4 2- and Cl- time series for the 1980s from 12 shallow snow pits across the Greenland ice sheet is used to evaluate the record of the 1982 El Chichón eruption and the potential for recording a moderate northern equatorial eruption in a single Greenland ice core. Composition of volcanic glass found in spring 1983 snow in one of the pits in the Summit region matches that from El Chichón glass, thereby verifying the deposition of material from the eruption. High Na+ and Cl- concentrations in this same layer probably represent deposition of the reaction products of …

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Layout For Visualizing Large Software Structures In 3d, Colin Ware, Glenn Franck, Monica Parkhi, Tim Dudley Dec 1997

Layout For Visualizing Large Software Structures In 3d, Colin Ware, Glenn Franck, Monica Parkhi, Tim Dudley

Center for Coastal and Ocean Mapping

There is increasing evidence that 3D visualization of complex structures has advantages over 2D visualization. While nested directed graphs are an important method of representing information in 2D or 3D, they must be effectively organized in order to be understood. Most work on graph layout has assumed that fully automatic layout is desirable. Through our work with graphs representing large software structures, we have found that, due to the importance of the semantic content, it is necessary to combine automatic layout with manual layout. This paper describes a system called GraphVisualizer3D, which was designed to help people understand large nested …

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Tidally Driven Residual Circulation In Shallow Estuaries With Lateral Depth Variation, Chunyan Li, James O'Donnell Dec 1997

Tidally Driven Residual Circulation In Shallow Estuaries With Lateral Depth Variation, Chunyan Li, James O'Donnell

CCPO Publications

Tidally driven residual circulation in shallow estuaries with lateral depth variation has been studied analytically using a two-dimensional, depth-averaged model. The solution is presented for a v-shaped channel. Exchange flow is found to be correlated with the topography. The magnitude of this exchange flow depends mainly on four parameters: the ratio between the minimum depth on the shoal and the maximum depth in the channel, the ratio between the tidal amplitude at the mouth and the mean depth, the ratio between the length of the estuary and the tidal wave length, and the ratio between the tidal timescale and the …

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Data Assimilation Experiments In The Gulf Stream Region: How Useful Are Satellite-Derived Surface Data For Nowcasting The Subsurface Fields?, Tal Ezer, George L. Mellor Dec 1997

Data Assimilation Experiments In The Gulf Stream Region: How Useful Are Satellite-Derived Surface Data For Nowcasting The Subsurface Fields?, Tal Ezer, George L. Mellor

CCPO Publications

Satellite-derived surface data have become an important source of information for studies of the Gulf Stream system. The question of just how useful these datasets are for nowcasting the subsurface thermal fields, however, remains to be fully explored. Three types of surface data-sea surface temperature (SST), sea surface height (SSH), and Gulf Stream position (GSP)-are used here in a series of data assimilation experiments to test their usefulness when assimilated into a realistic primitive equation model. The U.S. Navy's analysis fields from the Optimal Thermal Interpolation System are used to simulate the surface data and to evaluate nowcast errors. Correlation …

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Evidence For A Shore-Normal Energy Gradient And Its Character In The Speiekeroog Back Barrier Tidal Flats, German North Sea Coast, N Nyandwi Dec 1997

Evidence For A Shore-Normal Energy Gradient And Its Character In The Speiekeroog Back Barrier Tidal Flats, German North Sea Coast, N Nyandwi

Tanzania Journal of Science

Sediment distribution in the Spiekeroog backbarrier tidal flats has been studied with the aim of identifying the factors controlling their deposition. Form the mainland coast northwards three physiographic units are recognizable namely, the tidal flats adjacent to the coast, the tidal channels with the intervening flats and the dunes and tidal flats adjoining Spiekeroog island. The areal distribution of the sand fraction (˂4.0 phi) shows a shore normal energy gradient with increasing energy towards the sea. Very fine sands are found very close to the mainland coast, fine to very fine in the central part and fine sand on the …

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Requirements, Design And Prototype Of A Virtual User Interface For The Afit Virtual Spaceplane, John M. Lewis Dec 1997

Requirements, Design And Prototype Of A Virtual User Interface For The Afit Virtual Spaceplane, John M. Lewis

Theses and Dissertations

The United States Air Force is evaluating the feasibility of designing a military spaceplane capable of accomplishing military objectives from a low earth orbit and atmospheric flight regimes. Current efforts are involved in determining the scientific, operational, and budgetary constraints associated with this concept. This thesis looks at the exploration of new interface techniques associated with the design of a virtual spaceplane and is a subset of the overall virtual spaceplane effort which will assist researchers in determining the feasibility of a military spaceplane. Interface techniques are integrated into a virtual user interface that is designed to accommodate expected operations …

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Atmospheric Turbulence Scintillation Effects On Wavefront Tilt Estimation, James A. Louthain Dec 1997

Atmospheric Turbulence Scintillation Effects On Wavefront Tilt Estimation, James A. Louthain

Theses and Dissertations

A new atmospheric turbulence screen generator is developed for use in performance calculations of adaptive optics systems valid over a wide range of atmospheric turbulence parameters. The screen generator accounts for diffraction effects caused by weak turbulence and incorporates the phase, amplitude, and cross statistics of the perturbed optical field. The wavefront's phase and amplitude perturbations are taken from the correlation functions developed by Lee and Harp and the cross correlation of the phase and amplitude derived in this thesis. The screen generator uses a modal representation to perform a Fourier series expansion of the wavefront phase and amplitude over …

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Air-Snow Exchange Investigations At Summit, Greenland: An Overview, Jack E. Dibb, J L. Jaffrezo Nov 1997

Air-Snow Exchange Investigations At Summit, Greenland: An Overview, Jack E. Dibb, J L. Jaffrezo

Earth Sciences

The Greenland Ice Sheet Project 2 (GISP2) and Greenland Ice Core Project (GRIP) deep drilling programs at Summit, Greenland included support (both logistical and scientific) of extensive investigation of atmospheric transport and air-snow exchange processes of gases and particles relevant to the interpretation of the ice-core records. Much of the sampling for the air-snow exchange investigations was conducted at a unique solar-powered camp 30 km southwest of the GISP2 drill camp (even further from the GRIP camp) and was characterized by a high degree of international collaboration and cooperation. The wide range of expertise and analytical capabilities of the 20-plus …

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Vertical Profiles Of Bromoform In Snow, Sea Ice, And Seawater In The Canadian Arctic, William T. Sturges, Glenn F. Cota, Paul T. Buckley Nov 1997

Vertical Profiles Of Bromoform In Snow, Sea Ice, And Seawater In The Canadian Arctic, William T. Sturges, Glenn F. Cota, Paul T. Buckley

CCPO Publications

Bromoform (CHBr3) was measured in vertical profiles from the snow surface through the snowpack, sea ice, and water column to the seafloor at Resolute Bay, Canada, in the sprig of 1992. Elevated concentrations of bromoform were observed in both the ice (32-266 ng L-1 by liquid water volume) and seawater (~ 20 ng L-1 ) at the ice-water interface, associated with bromoform emission from ice microalgae. A surprising finding was a second horizon of high bromoform concentrations (336-367 ng L-1) in sea ice at the snow-ice interface. Chlorophyll and salinity were also elevated in …

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A Validation Of The Parameterized Real-Time Ionospheric Specification Model (Prism) Version 1.7b, Shawn D. Filby Nov 1997

A Validation Of The Parameterized Real-Time Ionospheric Specification Model (Prism) Version 1.7b, Shawn D. Filby

Theses and Dissertations

The most current version of the Parameterized Real-time Ionospheric Specification Model (PRISM), version 1.7b, was validated using Digital Ionospheric Sounding System (DISS) measurements of F2 layer critical frequency (foF2) and F2 peak electron density height (hmF2) as the "ground truth." PRISM was executed, first, with no real-time input parameter and, second, with Global Positioning System (GPS) Total Electron Content (TEC) measurements as the sole real-time parameter. Hourly values of hmF2 and foF2 over 123 days in 1994-1996 (solar minimum conditions) and covering three seasons (equinox, summer solstice, and winter solstice) were compared for Wallops Island, Virginia, and Point Arguello, California, …

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Port Everglades Macroinvertebrate Monitoring: Monitoring Of Benthic Macroinvertebrate Assemblages At The Southport Turning Basin And Adjacent Areas Of John U. Lloyd State Recreation Area: Final Report, Charles G. Messing, Richard E. Dodge Oct 1997

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

Marine & Environmental Sciences Faculty Reports

Monitoring of benthic macroinvertebrate assemblages in the vicinity of Port Everglades Southport began in September 1988 in anticipation of dredging of the Southport Turning Notch and concomitant mitigation of mangrove habitats at adjacent areas of John U. Lloyd State Recreation Area. Twice-yearly surveys were carried out from September 1988 to January 1991 by Sheldon Dobkin (Florida Atlantic University), and subsequently, from August 1991 to January 1997, under the supervision of Charles G. Messing and Richard E. Dodge (Nova Southeastern University Oceanographic Center). From 1990 onward, surveyed sites consisted of 11 Ponar grab stations, 11 mangrove crab census stations, and three …

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Circulation, Vol. 5, No. 1, Center For Coastal Physical Oceanography, Old Dominion University Oct 1997

Circulation, Vol. 5, No. 1, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Fall 1997 issue of CCPO Circulation featuring article "CCPO, ODU, and Internet2"

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An Analysis Of Tropical Transport: Influence Of The Quasi-Biennial Oscillation, Eugene C. Cordero, S. Randolph Kawa, Mark R. Schoeberl Jul 1997

An Analysis Of Tropical Transport: Influence Of The Quasi-Biennial Oscillation, Eugene C. Cordero, S. Randolph Kawa, Mark R. Schoeberl

Faculty Publications, Meteorology and Climate Science

An analysis of over 4 years of Upper Atmosphere Research Satellite (UARS) measurements of CH4, HF, O3, and zonal wind are used to study the influence of the quasi-biennial oscillation (QBO) on constituent transport in the tropics. At the equator, spectral analysis of the Halogen Occultation Experiment (HALOE) and Microwave Limb Sounder (MLS) observations reveals QBO signals in constituent and temperature fields at altitudes between 20 and 45 km. Between these altitudes, the location of the maximum QBO amplitude roughly corresponds with the location of the largest vertical gradient in the constituent field. Thus, at 40 …

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Circulation, Vol. 4, No. 4, Center For Coastal Physical Oceanography, Old Dominion University Jul 1997

Circulation, Vol. 4, No. 4, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Summer 1997 issue of CCPO Circulation featuring article "HF Radar: Is It Ready for Prime Time"

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Simulations Of The Atlantic Ocean With A Free Surface Sigma Coordinate Ocean Model, Tal Ezer, George L. Mellor Jul 1997

Simulations Of The Atlantic Ocean With A Free Surface Sigma Coordinate Ocean Model, Tal Ezer, George L. Mellor

CCPO Publications

A sigma coordinate, free surface numerical model with turbulence dynamics has been implemented for the Atlantic Ocean and the Greenland Sea, from 80°S to 80°N. It is driven at the surface by monthly mean sea surface temperature and wind stress climatologies and is executed for 30 years. This is the first time that a model of this type, previously used mostly for coastal and regional simulations, has been implemented for the entire Atlantic Ocean and run for a long period of time. The model horizontal circulation, thermohaline overturning circulation, and meridional heat fluxes are described; the results are compared with …

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Systematics Of The Freshwater Amphipod Genus Crangonyx (Crangonyctidae) In North America, Jun Zhang Jul 1997

Systematics Of The Freshwater Amphipod Genus Crangonyx (Crangonyctidae) In North America, Jun Zhang

Biological Sciences Theses & Dissertations

The systematics of the amphipod genus Crangonyx of North America (north of Mexico) is revised, based on available collections (ca. 2240) and literature dealing with the genus. A grand total of 42 North America species of Crangonyx are recognized in the present study, 24 of them new to science. All species are described or redescribed and figured, utilizing external morphological features. Keys to both species groups and individual species are given. Phylogenetic trees are built using computer programs (PAUP, Hennig86, MacClade) based on 26 characters. Wagner parsimony produced 18 parsimonious trees and Fitch parsimony produced 45 trees. The consensus tree …

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Resuspension And Transport Of Fine Sediments By Waves, Chiang C. Mei, She-Jun Fan, Kang-Ren Jin Jul 1997

Resuspension And Transport Of Fine Sediments By Waves, Chiang C. Mei, She-Jun Fan, Kang-Ren Jin

OES Faculty Publications

Although waves are the primary cause of sediment resuspension in the nearshore zone, in existing theoretical models, long-scale currents induced by the mean wind are often taken to be the only agent for the diffusion and convection of resuspended sediments. We present here theoretical examples where waves play a direct role in all aspects of sediment transport. Details are given for the simple case where only waves are present; the wave-induced current and diffusivity are shown to be no less important than similar factors in the wind-driven current. Hence, in a comprehensive model, one should include not only the current …

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Parametrically Resonant Surface Waves In A Rectangular Basin, Wu-Ting Tsai Jun 1997

Parametrically Resonant Surface Waves In A Rectangular Basin, Wu-Ting Tsai

Journal of Marine Science and Technology–Taiwan

We consider the resonant motion of a layer of fluid in a twodimensional rectangular basin forced to oscillate vertically. The equation governing the slowly-varying amplitude is derived using the multiple-scales method of perturbation analysis. The solution of the evolution equation is obtained analytitally. For steady harmonic responses, the present result compares remarkably well with available experimental measurements and is an improvement over existing third-order perturbation calculations. For unsteady (periodic) motions, the periods are computed as a function of motion amplitudes. The presence of internal resonance is discussed briefly.

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Use Of Fluorescence Microscopy In An Assay Of Sperm Density For The Gorgonian Coral, Plexaura Kuna, Timothy D. Swain, K. Kim, H. R. Lasker Jun 1997

Use Of Fluorescence Microscopy In An Assay Of Sperm Density For The Gorgonian Coral, Plexaura Kuna, Timothy D. Swain, K. Kim, H. R. Lasker

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

The density of sperm in the water column during the broadcast spawning events of marine invertebrates is often undetermined or reported in terms of fertilization potential. The density of sperm during such events can be determined by directly counting numbers of spermatozoa using a modification of the acridine orange direct count (AODC) technique for enumerating bacteria. A number of variables in the handling and processing of samples may bias estimates. Sample collection in glass and rapid fixation and filtration are necessary for reproducible estimates. Once filtered, samples are stable for many months, and counts on filters that were poorly stained …

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Agrometeorological Aspects Of Crop Production In Temperate Kashmir, Badrul Hasan Jun 1997

Agrometeorological Aspects Of Crop Production In Temperate Kashmir, Badrul Hasan

Drought Network News (1994–2001)

In our recent article on forecasting uncertain weather over temperate Kashmir (India) (Drought Network News, Vol. 9, No. 1, pp. 12–14), we tried to characterize the crop-growing environments by giving long-term means of various agrometeorological parameters (such as air temperature, relative humidity, precipitation, and hours of bright sunshine). Forecast analysis for changes in temperature and precipitation events indicated an overall reliability of about 50%. Changes in minimum temperature could be forecasted relatively more accurately than changes in maximum temperature. Precipitation events were more uncertain during summer (May to October), which happens to be an important season from the …

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National Drought Mitigation Center Involved In Development Of Natural Hazards Map, Michael J. Hayes Jun 1997

National Drought Mitigation Center Involved In Development Of Natural Hazards Map, Michael J. Hayes

Drought Network News (1994–2001)

The National Drought Mitigation Center (NDMC) is involved in a project with several other agencies and organizations in Canada, Mexico, and the United States to develop a map of the major natural hazards that threaten North America. Work on the project began in February 1995. Since then, there have been three working group meetings, with the most recent meeting taking place in Guadalajara, Mexico, in February 1997. Project leaders include Dr. Chris Tucker (Emergency Preparedness Canada), Dr. Joe Golden (National Oceanic and Atmospheric Administration [NOAA]), Dr. Rosalind Helz (U.S. Geological Society [USGS]), and Dr. Mario Ordaz- Schroeder (Centro Nacional de …

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Workshop On Drought And Desertification: Report On The Workshop And Recommendations, J. Lomas Jun 1997

Workshop On Drought And Desertification: Report On The Workshop And Recommendations, J. Lomas

Drought Network News (1994–2001)

The Workshop on Drought and Desertification was held in Israel from 26 to 30 May 1997. Forty-four participants from Africa, Asia, and Europe took part in the Workshop, which was sponsored by WMO. Three foreign experts provided in-depth analysis on drought and drought preparedness—Dr. O. Brunini (Campinas, Brazil), Prof. S. Mei (CAAS, Beijing, China), and Dr. D. Wilhite (University of Nebraska, USA), in addition to the Israeli lecturers.

Presentations by lecturers and discussions were conducted under the following four main headings:
1. Drought and Desertification Definitions.
2. Drought Causes and Management Response.
3. Drought Monitoring and Mitigation.
4. Assessing Drought …

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A Case Study Of The Deficit Spell Index For India’S Semiarid Delhi Region, K. K. Nathan Jun 1997

A Case Study Of The Deficit Spell Index For India’S Semiarid Delhi Region, K. K. Nathan

Drought Network News (1994–2001)

The Delhi region, the national capital region of India, is locked in by adjoining states like Uttar Pradesh and Haryana. Delhi has a characteristic continental type of climate, with extreme dryness, intensely hot summers, and dry cold winters. According to climatologists, this region is classified as semiarid tropical steppe. The monsoon rainfall is very erratic during June–September, which is the kharif crop-growing season. The monsoon breaks over the Delhi region between the first and second week of July and withdraws by the last week of September. The average annual rainfall is about 712.5 mm, of which 80% is contributed by …

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Ndmc Conducting Regional Drought Planning Workshops Jun 1997

Ndmc Conducting Regional Drought Planning Workshops

Drought Network News (1994–2001)

The National Drought Mitigation Center is conducting a series of regional workshops, “Planning for the Next Drought,” around the country in 1997 and 1998. The first workshop was in Albuquerque, New Mexico, July 28–30. Plans are underway to conduct similar workshops in other regions. A second workshop will probably be held in Salt Lake City in late 1997, followed by workshops in the Southeast and Midwest in 1998. Because the workshops are sponsored by the U.S. Bureau of Reclamation, there is no registration fee.

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Localized Severe Drought During 1996 And Its Impact On Crop Production In Raipur District Of Central India, J. S. Urkurkar, V. K. Koshta, Diwakar Naidu, A. S. R. A. S. Sastri Jun 1997

Localized Severe Drought During 1996 And Its Impact On Crop Production In Raipur District Of Central India, J. S. Urkurkar, V. K. Koshta, Diwakar Naidu, A. S. R. A. S. Sastri

Drought Network News (1994–2001)

In Raipur district, the onset of the monsoon occurred in the 25th standard meteorological week (June 18–24). But after the onset of monsoonal rains, there was a lull in the monsoon for about 2 consecutive weeks. In the 28th week (July 9–15), the district received 77.6 mm of rainfall. This was equal to the normal value for that week. In the following (29th) week, the district received 96.8 mm rainfall, 38.9% more than the normal rainfall for that week.

Thus, the rice, soybean, and other crops sown with the onset of the monsoon in the 25th week suffered from acute …

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From The Director: June 1997, Donald A. Wilhite Jun 1997

From The Director: June 1997, Donald A. Wilhite

Drought Network News (1994–2001)

Drought policy continues to be a topic of much discussion in the United States. On June 12, the Western Drought Coordination Council (WDCC) met for the first time and adopted a work plan for 1997–98. The WDCC is committed to improving drought management in the western states through mitigation and preparedness. It is hoped that this Council, representing a partnership between federal, state, local, and tribal government, will serve as a model for other drought-prone regions of the United States. Four working groups (preparedness and mitigation; monitoring, assessment, and prediction; response; and communications) established by the Council will meet in …

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Western Drought Coordination Council: Frequently Asked Questions, Donald A. Wilhite Jun 1997

Western Drought Coordination Council: Frequently Asked Questions, Donald A. Wilhite

Drought Network News (1994–2001)

Contents:

What is the Western Drought Coordination Council (WDCC)?

What does the WDCC hope to accomplish?

What prompted the formation of the Council?

Preparedness and Mitigation

Monitoring, Assessment, and Prediction

Response

Communications

To Whom does the WDCC report?

How do I get in touch with the Council?

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Observation Of Large Diurnal Warming Events In The Near-Surface Layer Of The Western Equatorial Pacific Warm Pool, Alexander Soloviev, Roger Lukas Jun 1997

Observation Of Large Diurnal Warming Events In The Near-Surface Layer Of The Western Equatorial Pacific Warm Pool, Alexander Soloviev, Roger Lukas

Marine & Environmental Sciences Faculty Articles

Because of the relatively calm winds which prevail over the western Pacific warm pool, the diurnal cycle of temperature in the near-surface layer of the ocean is often quite pronounced. During the TOGA Coupled Ocean-Atmosphere Response Experiment (COARE), very high resolution measurements of near-surface thermohaline and turbulence structures were made using bowmounted probes and a free-rising profiler. Experimental data demonstrate a strong dependence of near-surface thermal structure on weather conditions, In calm weather, SST was observed to exceed 33.25°C; this was associated with a diurnal warming of more than 3°C in the top I m of the ocean. A 1-D …

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Sharp Frontal Interfaces In The Near-Surface Layer Of The Ocean In The Western Equatorial Pacific Warm Pool, Alexander Soloviev, Roger Lukas Jun 1997

Sharp Frontal Interfaces In The Near-Surface Layer Of The Ocean In The Western Equatorial Pacific Warm Pool, Alexander Soloviev, Roger Lukas

Marine & Environmental Sciences Faculty Articles

During the TOGA COARE rich horizontal temperature and salinity variability of the near-surface layer of the ocean in the western Pacific warm pool was observed. High-resolution measurements were made by probes mounted on the bow of the vessel in an undisturbed region at ~1.7-m depth during four COARE cruises of the R/V Moana Wave. The authors observed several tens of cases of periodic sharp frontal interfaces of width 1– 100 m and separation 0.2–60 km. The sharp frontal interfaces were often found in frontal regions and on the periphery of freshwater puddles. Maneuvers of the ship were conducted to determine …

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Announcements: June 1997 Jun 1997

Announcements: June 1997

Drought Network News (1994–2001)

Contents:

Regenerative Agriculture for the 21st Century

4th International Symposium on Environmental Geotechnology and Global Sustainable Development - Call for Abstracts

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