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Variability

Articles 31 - 39 of 39

Full-Text Articles in Oceanography

Hydrographic Variability On Decadal And Interdecadal Scales In The Northern Gulf Of Alaska, Nandita Sarkar Jul 2001

Hydrographic Variability On Decadal And Interdecadal Scales In The Northern Gulf Of Alaska, Nandita Sarkar

OES Theses and Dissertations

The mixed layer depth (MLD) in the North Pacific is important to vertical mixing and hence the flux nutrients into the euphotic zone. A time series of hydrographic measurements, tem perature and salinity versus depth, at a coastal site in the northern Gulf of Alaska is used to determine the seasonal and interannual variations in the MLD. Data from this station called GAK 1 (59°50.7‘X. 149C28.0'\V) in 203 m of water begin in 1974 and end in 1998. The MLD changes seasonally from about 50 m in summer to more than 130 m in winter. These changes are in response …

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Reconstructing Basin-Scale Eulerian Velocity Fields From Simulated Drifter Data, M. Toner, A. C. Poje, A. D. Kirwan, C. K. R. T. Jones, B. L. Lipphardt, C. E. Grosch Jan 2001

Reconstructing Basin-Scale Eulerian Velocity Fields From Simulated Drifter Data, M. Toner, A. C. Poje, A. D. Kirwan, C. K. R. T. Jones, B. L. Lipphardt, C. E. Grosch

CCPO Publications

A single-layer, reduced-gravity, double-gyre primitive equation model in a 2000 km x 2000 km square domain is used to test the accuracy and sensitivity of time-dependent Eulerian velocity fields reconstructed from numerically generated drifter trajectories and climatology. The goal is to determine how much Lagrangian data is needed to capture the Eulerian velocity field within a specified accuracy. The Eulerian fields are found by projecting, on an analytic set of divergence-free basis functions, drifter data launched in the active western half of the basin supplemented by climatology in the eastern domain. The time-dependent coefficients are evaluated by least squares minimization …

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Comparison Of Statistical And Model-Based Hindcasts Of Subtidal Water Levels In Chesapeake Bay, Kathryn Thompson Bosley, Kurt W. Hess Jan 2001

Comparison Of Statistical And Model-Based Hindcasts Of Subtidal Water Levels In Chesapeake Bay, Kathryn Thompson Bosley, Kurt W. Hess

CCPO Publications

Subtidal water levels in Chesapeake Bay, which can have amplitudes as large as 1 m at Baltimore, are an important component of total water levels. The most importance forcing mechanisms for these variations are surface winds over the Bay and coastal subtidal water levels. Two methods for hindcasting subtidal water levels in the Bay were developed: statistical prediction (based on multiple linear regression) and a barotropic numerical circulation model-based prediction. The hindcast water levels were compared with the observed values at three key locations (Chesapeake Bay Bridge Tunnel (CBBT) in the lower bay near the mouth, Solomons Island at midbay, …

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Frontogenesis In The North Pacific Oceanic Frontal Zones--A Numerical Simulation, Michael S. Dinniman, Michele M. Rienecker Jan 1999

Frontogenesis In The North Pacific Oceanic Frontal Zones--A Numerical Simulation, Michael S. Dinniman, Michele M. Rienecker

CCPO Publications

A primitive equation model [Geophysical Fluid Dynamics Laboratory's (GFDL's) MOM 2] with one degree horizontal resolution is used to simulate the seasonal cycle of frontogenesis in the subarctic frontal zone (SAFZ) and the subtropical frontal zone (STFZ) of the North Pacific Ocean. The SAFZ in the model contains deep (greater than 500 m in some places) regions with seasonally varying high gradients in temperature and salinity. The gradients generally weaken toward the east. The STFZ consists of a relatively shallow (less than 200 m in most places) region of high gradient in temperature that disappears in the summer/fall. The high …

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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 Sep 1996

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. …

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Seasonal And Mesoscale Variability In The Distribution Of Antarctic Krill, Euphausia Superba, West Of The Antarctic Peninsula, Cathy Meyer Lascara Apr 1996

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, …

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Transport, Potential Vorticity, And Current/Temperature Structure Across Northwest Providence And Santaren Channels And The Florida Current Off Cay Sal Bank, Kevin D. Leaman, Peter S. Vertes, Larry P. Atkinson, Thomas N. Lee, Peter Hamilton, Evans Waddell Jan 1995

Transport, Potential Vorticity, And Current/Temperature Structure Across Northwest Providence And Santaren Channels And The Florida Current Off Cay Sal Bank, Kevin D. Leaman, Peter S. Vertes, Larry P. Atkinson, Thomas N. Lee, Peter Hamilton, Evans Waddell

CCPO Publications

Currents and temperatures were measured using Pegasus current profilers across Northwest Providence and Santaren Channels and across the Florida Current off Cay Sal Bank during four cruises from November 1990 to September 1991. On average, Northwest Providence (1.2 Sv) and Santaren (1.8 Sv) contribute about 3 Sv to the total Florida Current transport farther north (e.g., 27°N). Partitioning of transport into temperature layers shows that about one-half of this transport is of ''18°C'' water (17°C-19.5°C); this can account for all of the ''excess'' 18°C water observed in previous experiments. This excess is thought to be injected into the 18°C layer …

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Mississippi River Flood Waters That Reached The Gulf Stream, Peter B. Ortner, Thomas N. Lee, Peter J. Milne, Rod G. Zika, M. Elizabeth Clarke, Guillermo P. Podesta, Peter K. Swart, Patricia A. Tester, Larry P. Atkinson, Walter R. Johnson Jan 1995

Mississippi River Flood Waters That Reached The Gulf Stream, Peter B. Ortner, Thomas N. Lee, Peter J. Milne, Rod G. Zika, M. Elizabeth Clarke, Guillermo P. Podesta, Peter K. Swart, Patricia A. Tester, Larry P. Atkinson, Walter R. Johnson

CCPO Publications

Distributions of physical, biological, and chemical parameters in Florida Keys coastal waters seaward of the reef track were surveyed on September 9 to 13, 1993, as part of a coordinated multidisciplinary study of surface transport processes. A band of low-salinity water was observed along the shoreward side of the Florida Current over the downstream extent of the survey from Miami to Key West. Biological and chemical indicators within the band, together with its large volume, satellite imagery, and a surface drifter trajectory suggested the recent Mississippi River flood as the source.

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Observations Of A Cyclonic Ring: Gulf Stream Coalescence Event Over The Blake Plateau, Julie Mcclean-Padman, Larry P. Atkinson Jan 1991

Observations Of A Cyclonic Ring: Gulf Stream Coalescence Event Over The Blake Plateau, Julie Mcclean-Padman, Larry P. Atkinson

CCPO Publications

Hydrographic data collected in September 1980 over the Blake Plateau were analyzed using a combination of empirical search and inverse techniques. Five sections, extending from the continental shelf break eastward across the Blake Plateau, were positioned at approximately 1-degrees intervals between 28-degrees and 32-degrees-N. The empirical search procedure was applied to four closed regions (boxes), constructed from adjacent sections, where each region was assumed to consist of two conservative layers. Five geostrophic velocity sections were obtained using the average optimum reference level for the four boxes. The inverse technique provided barotropic correction velocities that caused all layers to conserve mass. …

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