Climate Commons^™

On The Low-Frequency Current And Temperature Fluctuations Along The Shelf Break In The South Atlantic Bight, Sunny Yu Wu

OES Theses and Dissertations

Current and temperature data collected along the shelf edge in the South Atlantic Bight were analyzed using a spectral analysis technique. The power spectra of both alongshore currents and temperatures (upon removal of seasonal trends) in the mid- to lower water column suggest a significant energy peak at 28 days. The spatial characteristics of the fluctuations around this period band were determined using the frequency domain empirical orthogonal function (EOF) analysis applied to the concurrent current and temperature records. Consistent results were obtained from the upstream side of the Charleston Bump. Around the 28-day period, temperature seems to have little …

Continuous Assimilation Of Geosat Altimeter Data Into A Three-Dimensional Primitive Equation Gulf Stream Model, Tal Ezer, George L. Mellor

CCPO Publications

A three-dimensional data assimilation scheme is described and tested, using the Geosat altimeter data and a high-resolution, primitive equation, numerical ocean model of the Gulf Stream region. The assimilation scheme is based on an optimal interpolation approach in which data along satellite tracks are continuously interpolated horizontally and vertically into the model grid and assimilated with the model prognostic fields. Preprocessed correlations between surface elevation anomalies and subsurface temperature and salinity anomalies are used to project surface information into the deep ocean; model and data error estimates are used to optimize the assimilation. Analysis fields derived from the Navy's Optimum …

Invariant Manifolds Of A Toy Climate Model, Michael Toner

Mathematics & Statistics Theses & Dissertations

According to astronomical theory, ice ages are caused by variations in the Earth's orbit. However, ice core data shows strong fluctuations in ice volume at a low frequency not significantly present in orbital variations. To understand how this might occur, the dynamics of a two dimensional nonlinear differential equation representing glacier/temperature interaction of an idealized climate was studied. Self sustained oscillation of the autonomous equation was used to model the internal mechanisms that could produce these fluctuations. Periodic parametric modulation of a damped internal oscillation was used to model periodic climate response at double the external modulation period. Both phenomena …

Periodic And Homoclinic Orbits In A Toy Climate Model, M. Toner, A. D. Kirwan Jr.

Mathematics & Statistics Faculty Publications

A two dimensional system of autonomous nonlinear ordinary differential equations models glacier growth and temperature changes on an idealized planet. We apply standard perturbative techniques from dynamical systems theory to study small amplitude periodic orbits about a constant equilibrium. The equations are put in cononical form and the local phase space topology is examined. Maximum and minimum periods of oscillation are obtained and related to the radius of the orbit. An adjacent equilibrium is shown to have saddle character and the inflowing and outflowing manifolds of this saddle are studied using numerical integration. The inflowing manifolds show the region of …

Effect Of Wind Changes During The Last Glacial Maximum On The Circulation In The Southern Ocean, John M. Klinck, David A. Smith

CCPO Publications

Present-day surface wind stress climatology is manipulated to simulate wind conditions during the last glacial maximum. These estimated wind fields force a one-layer, wind-driven numerical model of the southern ocean to determine if a change in the strength of the surface wind stress can shift the location of the Antarctic Polar Front, which is part of the Antarctic Circumpolar Current. A change in the forcing by a factor of 0.5-2.0 results in a change in the speed of the flow by an identical factor with no change in position. However, if the present-day wind climatology is shifted meridionally there is …

A Comparison Of Gulf Stream Sea Surface Height Fields Derived From Geosat Altimeter Data And Those Derived From Sea Surface Temperature Data, Tal Ezer, George L. Mellor, Dong-Shan Ko, Ziv Sirkes

CCPO Publications

Two types of satellite data, Geosat altimeter data and sea surface temperature data (SST), are compared and evaluated for their usefulness in assimilation into a numerical model of the Gulf Stream region. Synoptic sea surface height (SSH) fields are derived from the SST data in the following way: first three-dimensional temperature and salinity analysis fields are obtained through the Optimum Thermal Interpolation System (OTIS), and then SSH fields are calculated using a primitive equation, free-surface, numerical model running in a diagnostic mode. The aforementioned SSH fields are compared with SSH fields obtained from the Geosat altimeter data. Use of Geosat …

Heat Storage And Transport Processes In The Tropical Atlantic Ocean, Andras Kapolnai

OES Theses and Dissertations

Heat storage and transport processes of the tropical Atlantic play an important role in the climate of three continents. The exploration of how the warm water mass maintenance in the equatorial basin depends on various external factors is therefore an important task. This study examines the annual cycle of the warm water mass formation and its transport in the equatorial Atlantic through the interaction of the atmospheric and oceanic boundary layers. Key features of the model are the sea level wind field, equatorial upwelling rate and escape transport of the formed warm water out of the equatorial basin.

The model …

Variability Of Surface Pigment Concentrations In The South Atlantic Bight, Charles R. Mcclain, James A. Yoder, L. P. Atkinson, J. O. Blanton, T. N. Lee, J. J. Singer, Frank Muller-Karger

CCPO Publications

A 1‐year time sequence (November 1978 through October 1979) of surface pigment images from the South Atlantic Bight (SAB) was derived from the Nimbus 7 coastal zone color scanner. This data set is augmented with in situ observations of hydrographic parameters, freshwater discharge, sea level, coastal winds, and currents for the purpose of examining the coupling between physical processes and the spatial and temporal variability of the surface pigment fields. The SAB is divided into three regions: the east Florida shelf, the Georgia‐South Carolina shelf and the Carolina Capes. Six‐month "seasonal" mean pigment fields and time series of mean values …

The Physics Of The Antarctic Circumpolar Current, Worth D. Nowlin, John M. Klinck

CCPO Publications

A region of transition of surface water characteristics from subantarctic to Antarctic and an associated eastward flowing Antarctic Circumpolar Current (ACC) have long been recognized to exist as a band around Antarctica. In this review we summarize the most important observational and theoretical findings of the past decade regarding the ACC, identify gaps in our knowledge, and recommend studies to address these. The nature of the meridional zonation of the ACC is only now being revealed. The ACC seems to exist as multiple narrow jets imbedded in, or associated with, density fronts (the Subantarctic and Polar fronts) which appear to …

Effects Of El Nino On Local Hydrography And Growth Of The Giant Kelp, Macrocystis Pyrifera, At Santa Catalina Island, California, Richard C. Zimmerman, Deborah L. Robertson

OES Faculty Publications

Deepened isotherms associated with El Niño resulted in severe nutrient limitation and very low kelp productivity during the last half of 1983. Frond growth rates were so low that terminal blades formed before reaching the surface, eliminating the canopy. Frond initiation rates were also extremely low, resulting in significant reductions in mean plant size. Plants growing above 10m were more severely affected than plants at 20m. Nutrient pulses associated with internal waves are thus critical for survival of Macrocystis pyrifera in nutritionally marginal habitats in Southern California.

A High-Resolution Bathymetry Map For The Marguerite Bay And Adjacent West Antarctic Peninsula Shelf For The Southern Ocean Globec Program, S. T. Bolmer, R. C. Beardsley, C. Pudsey, P. Morris, P. Wiebe, Eileen E. Hofmann, J. Anderson, A. Maldonado

OES Faculty Publications

One objective of the U.S. Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program is to gain a better understanding of the sea floor bathymetry in the program study area. Much of Marguerite Bay and the adjacent shelf west of the Antarctic Peninsula were poorly charted when the SO GLOBEC program started in 2000. Before the first SO GLOBEC cruise, an improved local area version (ETOPO8.2A) was created from the Smith and Sandwell (1997) topo_8.2.img 2-minute digital gridded bathymetry for the study area. The first SO GLOBEC mooring cruise on the R/V Lawrence M. Gould (March 2001) showed that the …

Climatology Of The Southeastern United States Continental Shelf Waters, Larry P. Atkinson, Thomas N. Lee, Jackson O. Blanton, William S. Chandler

CCPO Publications

Data from 2872 hydrographic stations have been used to determine the oceanographie climatology of the southeastern United States continental shelf waters. The data were sorted by each degree of latitude and by depth into three zones (0–20 m, 21–40 m, 41–60 m). Inner shelf water temperatures were similar to adjacent land air temperatures, while outer shelf temperatures were moderated by the Gulf Stream. Minimum and maximum water temperatures occurred in Georgia and South Carolina inner shelf water. Bottom temperatures were unusually low off Florida in the summer probably because of shelf break upwelling. Surface salinity was lowest adjacent to the …

The Chemical And Biological Effect Of A Gulf Stream Intrusion Off St. Augustine, Florida, Larry P. Atkinson, Gustav-Adolf Paffenhöfer, William M. Dunstan

CCPO Publications

During a 3-day anchor station in shelf waters off St. Augustine, Florida we observed the effect of an intruding mass of deeper Gulf Stream water. The shelf waters were relatively low in nutrients and salinity while the Gulf Stream waters were high in salinity and nutrients. Onshore currents correlated with increases in nitrate and chlorophyll concentrations.

The advection of higher nutrient Gulf Stream water coincided with high chlorophyll (∼ mg chl a m⁻³) concentrations and dense populations of Phaeocystis pouchetii (up to 3.12 × 10°1⁻¹). Zooplankton sampling was impossible in the bottom layer because of the …

Modes Of Gulf Stream Intrusion Into The South Atlantic Bight Shelf Waters, Larry P. Atkinson

CCPO Publications

Consideration is given to the intrusion of Gulf Stream waters into the shelf waters of the South Atlantic Bight. It is observed that three modes of intrusion may occur, depending on particular ambient shelf water density. They are override, interleave, and bottom intrusion. It is noted that: (1) except in January, when the shelf water densities are relatively higher, 20°C Gulf Stream water can form a bottom intrusion anywhere along the coast, (2) Gulf Stream waters of 24°C can only form bottom intrusions from April to November, and (3) the rest of the year, 24°C waters interleave or override.

Effect Of Air Bubble Solution On Air-Sea Gas Exchange, Larry P. Atkinson

CCPO Publications

Recent data on ambient wave generated oceanic bubble spectra (Medwin, 1970) permit the calculation of the influence of bubble solution on air-sea gas exchange. Schulkin's formula is used to estimate the depth variation of bubbles, and a square law is used to estimate the increase of bubble volume with wind speed. Calculations indicate that bubble solution can be a very significant factor in gas exchange. Bubble solution enhances gas input and retards degassing of the water column. Preliminary data show a lag time of about 5 hours in the response of the water column to an atmospheric pressure change.