ALBERT

Beschreibung: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2001

Beschreibung: Half of the ocean crust is formed at spreading centers with total opening rates less than 40 km/Myr. The objective of this Thesis is to investigate temporal variations in active ridge processes and crustal aging at slow-spreading centers by comparing axial crustal structure with that on conjugate flanks of the slow-spreading Mid-Atlantic Ridge (MAR) (full rate, 20 km/Myr) and the ultra-slow spreading Southwest Indian Ridge (SWIR) (full rate, 14 km/Myr). Seismic refraction data collected along the rift valley and flanking rift mountains of the OH-l segment (35°N) at the MAR show that the entire crustal section is constructed within a zone that is less than 5 km wide. Shallow-level hydrothermal circulation within the axial valley is suggested by the rift mountain seismic profiles, which show that the upper crust is 20% thinner and 16% faster along strike than zero-age crust. These effects probably result from fissure sealing within the extrusive crust. Deeper crustal velocities remain relatively constant at the segment midpoint within the first 2 Myr, but are reduced near the segment offsets presumably by faulting and fracturing associated with uplift out of the rift valley. A temporal variation in axial melt supply is suggested by a 15% difference in along-strike crustal thickness between the rift valley and rift mountains, with relatively less melt supplied today than 2 Ma. Crustal accretion at the SWIR appears to occur in a similar manner as at the MAR, although gravity and seismic data indicate that the average crustal thickness is 2-4 km less at the ultra-slow spreading SWIR. A 25 Myr record on both flanks of the ridge shows that seafloor spreading has been highly asymmetric through time, with 35% faster crustal accretion on the Antarctic (south) plate. A small-offset non-transform discontinuity between two ridge segments is just as stable as two neighboring transform discontinuities, although a single mantle Bouguer gravity anomaly centered over the non-transform offset indicates that this boundary does not significantly perturb underlying mantle flow. Off-axis magnetic anomalies are recorded with high fidelity despite the very low spreading rates and the absence of a basaltic upper crust in one area. The lower crust may be the dominant off-axis carrier of the magnetic signal, contrary to traditional models of crustal magnetic structure. Morphological and gravity data show evidence of asymmetric crustal accretion across the SWIR ridge axis, with slightly warmer mantle temperatures beneath the slower-spreading African (north) plate.

Beschreibung: Funding was provided by the National Science Foundation through Contract No. OCE-9300450 and by the Joint Oceanographic Institutions through Subcontract No. JSC1-00.

Beschreibung: Originally issued as Reference No. 60-46, series later renamed WHOI-.

Beschreibung: National Science Foundation under Research Grant NSF 12556

Beschreibung: The (Lagrangian) motion of a fluid particle was contrasted with the (Eulerian) flow past a fixed point in space during this twenty-fourth summer program in geophysical fluid dynamics at the Woods Hole Oceanographic Institution.

Beschreibung: Office of Naval Research under Contract N00014-82-G-0079 and National Science Foundation Grant MCS-82-00450. Partial support from the Center for Analysis of Marine Systems (CAMS) at Woods Hole Oceanographic Institution.

Beschreibung: Originally issued as Reference No. 60-46, series later renamed WHOI-.

Beschreibung: This ten-week work-study-discussion program is centered about a formal course called Geophysical Fluid Dynamics. Eight participants are selected from graduate and postgraduate applicants. In the discussions emphasis is placed on the formulation of tractable research problems in geophysics. The participants are encouraged to work on satisfactory problems thus formulated and to continue with their research after returning to their respective institutions.

Beschreibung: National Science Foundation under Research Grant NSF 12556

Beschreibung: Originally issued as Reference No. 59-53, series later renamed WHOI-.

Beschreibung: This ten-week work-study-discussion program is centered about a formal course called Geophysical Fluid Dynamics. Eight participants are selected from graduate and postgraduate applicants. In the discussions emphasis is placed on the formulation of tractable research problems in geophysics. The participants are encouraged to work on satisfactory problems thus formulated and to continue with their research after returning to their respective institutions.

Beschreibung: National Science Foundation under Research Grant NSF G-9125

Beschreibung: Originally issued as Reference no. 61-39, series later renamed WHOI-.

Beschreibung: National Science Foundation under Research Grant NSF G-16973

Beschreibung: Four principal lecturers shored the task of presenting the subject "Coherent Features in Geophysical Flows" to the participants of the twenty-second geophysical fluid dynamics summer program. Glenn Flierl introduced the topic and the Kortweg-de Vries equation via a model of finite amplitude motions on the beta plane. He extended the analysis to more complex flows in the ocean and the atmosphere and in the process treated motions of very large amplitude. Larry Redekopp's three lectures summarized an extensive body of the mathematical literature on coherent features. Andrew Ingersoll focussed on the many fascinating features in Jupiter's atmosphere. Joseph Keller supplemented an interesting summary of laboratory observations with suggestive models for treating the flows.

Beschreibung: Office of Naval Research under Contract N00014-79-C-0671

Beschreibung: Those attending G.F.D. 1984 were introduced to the novel topic of Geological Fluid Mechanics by our Principal Lecturer, Herbert Huppert. He presented his studies both as a discipline with recent fascinating successes, and as a challenge to his listeners to further isolate mathematically tractable examples of these multi-component flows. Geological Fluid Mechanics has been the responsible process for the formation and modification of most of the geological objects studied today. The dynamics of fluid mixtures in magma chambers, the changing fluid boundary conditions and composition during selective crystallization of parts of the melt, and the separation of fluid fractions of different density and viscosity all represent areas in which quantitative theories are currently being tested. However, equally many areas, including convection mechanisms in the Earth's core and quantitative predictions for upper mantle motion, resist simplistic modeling.

Beschreibung: Office of Naval Research under contract N00014-82-G-0079 and the National Science Foundation under Grant MCS-82-800450. Partial support acknowledged from the Center for Anatysis of Marine Systems (CAMS) at the Woods Hole Oceanographic Institution. CAMS is supported by The Exxon Foundation, Mobil Foundation, Inc., The Ambrose Monell Foundation, The R. R. Mellon Family Foundation., the Atlantic Richfield Foundation, and by an anonymous donor.

Beschreibung: The explosive growth of dynamieal systems theory in the past two decades stems in large part from the realization that it is applicable to many natural phenomena. Indeed, much o f the theoretical development has been sparked by numerical and laboratory experiments which exhibit ordered sequences of behavior that call for a general framework of interpretation We have been fortunate this summer to have had in residence both pioneers and developers of dynamical systems theory and its applications to fluid mechanics. Several recent texts contain the basic principles that Ed Spiegel used as a springboard for five lectures in which he exposed us to elementary examples of bifurcation and chaos, to symmetry breaking, normal forms and temporal and spatial disorder, as well as to pertinent fluid mechanical and astrophysical phenomena. Yves Pomeau continued the development with an elegant summary of different types of intermittency . Stephan Fauve agree to write up his impressive seminars on phase instability and turbulence as an extension of the lecture series. Many of the remaining seminars introduced new concepts in the theory, some with specific examples, others via mathematical development, and still others through ways of interpreting the data that emerge from calculations and experiments. As an outstanding example of this, Albert Libchaber has demonstrated the fascinating correspondence between the frequencies observed in one of his recent fluid mechanics experiments and results from number theory relating the Fibonacci series to the golden mean.

Beschreibung: Office of Naval Research under contract NO0014-82-6-0079 and the National Science Foundation under Grants MCS-82-000450 and DMS-85-04166.

Beschreibung: Originally issued as Reference No. 63-34, series later renamed WHOI-.

Beschreibung: This year's lectures by Derek Moore form a detailed report of investigations on the fluid motion caused by the motion of a body in a homogeneous rotating fluid. The emphasis has been on the significance of the Taylor-Proudman theorem and the departure of the fluid from the behavior described by the Taylor-Proudman theorem. The plan was to probe deeply into one problem and thereby acquire information in a wider area of study of rotating fluids.

Beschreibung: National Science Foundation under Research Grant NSF GE-15l8

Beschreibung: Originally issued as Reference No. 66-46, series later renamed WHOI-.

Beschreibung: The lecturers, Drs. Howard, Stern and Veronis, have introduced the participants to several aspects of geophysical fluid dynamics at the frontiers of current research. Their choice of topic and its development was to serve, on one hand, a pedagogic function and, on the other, to suggest a variety of allied unsolved problems.

Beschreibung: National Science Foundation

Beschreibung: Originally issued as Reference No. 65-51, series later renamed WHOI-.

Beschreibung: National Science Foundation

Beschreibung: Originally issued as Reference No. 68-72, series later renamed WHOI-.

Beschreibung: The general circulation of the oceans was the topic of concentration for the 1968 WHOI Summer Program in Geophysical Fluid Dynamics

Beschreibung: National Science Foundation

Beschreibung: Originally issued as Reference No. 69-41, series later renamed WHOI-.

Beschreibung: The principal theme of this eleventh Summer Program has been Astrophysical Fluid Dynamics. As in the past, we have explored the region of overlap in technique and theory of our summer theme and other aspects of Fluid Dynamics. An interesting example of this overlap is the application of the physics of salt-finger instability, a significant oceanographic process, to instabilities due to differential rotation in the sun, a critical problem in stellar evolution.

Beschreibung: National Science Foundation

Beschreibung: The central topic of this seventeenth Geophysical Fluid Dynamics program was fluid motion in the earth's mantle and core. Our principal lecturer, Dan McKenzie, first addressed himself to the task of separating solid behavior of the mantle from fluid behavior. When the level of protest diminished Dan advanced to his numerical studies of mantle convection. The relationship of these numerical experiments and geophysical observables was impressive indeed for this first generation of mantle modeling. Intertwined seminars from P. Molnar, B. Parsons, J. Sclater and T. Atwater exposed us to data gathering and its rationale at the frontiers of geophysics. The fluid properties of the core may be less suspect than those of the mantle, but how and why the core fluid moves is still a mystery. Our associate principal lecturer, Fritz Busse, discussed the geomagnetic evidence for core motion. Then moving quickly to the more abstract problems of model geodynamos, Fritz described in five lectures his achievement of a first complete dynamic dynamo driven by convection.

Beschreibung: National Science Foundation

Beschreibung: This was the twentieth Geophysical Fluid Dynamics program at Woods Hole. Stephen Childress of the Courant Institute was our principal lecturer. Dynamo theory, with all its interdisciplinary facets was our central theme. Geomagnetism and the solar magnetic cycle were brought closer to comprehension, yet none claimed a detailed predictive theory was near at hand. Perhaps J. Keller's lecture, entitled "Smooth equations for rough problems", best characterized the nature of these studies. Even then, the smooth equations are quite nonlinear, with Finite-amplitude magnetic solutions yet to be explored. Lectures intertwined with those of Childress exposed us to topics beside and outside his emphasis on a convective geodynamo.

Beschreibung: Office of Naval Research under Contract N00014-78-G0072

Beschreibung: Originally issued as Reference No. 61-39, series later renamed WHOI-.

Beschreibung: This ten-week work-study-discussion program was centered about a formal course called Geophysical Fluid Dynamics. Sixteen participants were selected from graduate and postgraduate applicants. In the discussions emphasis was placed on the formulation of tractable research problems in geophysics. The participants were encouraged to work on satisfactory problems thus formulated and to continue with their research after returning to their respective institutions.

Beschreibung: National Science Foundation under Research Grant NSF G-16973

Beschreibung: Originally issued as Reference No. 62-33, series later renamed WHOI-.

Beschreibung: National Science Foundation under Research Grant NSF22332

Beschreibung: Originally issued as Reference No. 62-38, series later renamed WHOI-.

Beschreibung: Includes the preprint "Mixing-length Analyses of Turbulent Thermal Convection at Arbitrary Prandtl Number" - R. Kraichnan (1962). N.Y.U. Research Report No. HSN-6.

Beschreibung: National Science Foundation under Research Grant NSF22332

Beschreibung: Originally issued as Reference No. 64-46, series later renamed WHOI-.

Beschreibung: Two distinctive features of large-scale geophysical flows are that they are dominated by the earth's rotation and that they are turbulent. This year's lecture program was an exploration of recent achievements in the study of, first, the simplest examples of turbulence, and second, the rotational constraint.

Beschreibung: National Science Foundation and Travelers' Research Center, Inc

Beschreibung: Nonlinear wave interactions formed the theme of the fifteenth summer program in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution. Owen Phillips was our principal lecturer on this subject, He chose to emphasize interactions among small numbers of discrete wave modes, including both internal and surface gravity waves in his discussions. His lectures provided a stimulating introduction to this important subject. Phillips' lectures were supplemented by a lecture by William Simmons on experiments with interacting internal waves, and a lecture by Carl Wunsch on internal waves in the ocean. Later in the summer, Wunsch gave us a lecture series on practical time-series analysis.

Beschreibung: We thank the National Science Foundation for their continuing support.

Beschreibung: The effect of gravity on fluids of varying density is of fundamental importance in natural flows. This subject formed the topic of concentration for the fourteenth summer program in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution. We had the good fortune to hear Stewart Turner lecture on stratified flows just after he had completed the manuscript for his book on the subject. Turner chose to emphasize nonlinear and turbulent aspects of stratified flows and, therefore, had to give up the deductive approach in favor of treatments based on dimensional analysis and similarity arguments. This summary of the many experimental studies of these flows increased our awareness of the fascinating variety of phenomena in which stratification plays so vital a role.

Beschreibung: Supported by the Division of Fluid Dynamics, Oceanography and Applied Mathematics of the Office of Naval Research.

Beschreibung: This year the central topic was the general circulation of the oceans. Some of the basic ideas used in wind-driven and thermohaline studies were presented in the introductory course of lectures and simple models that have guided our thinking in the development of the topic were discussed. As part of the introductory lectures Peter Niiler developed a model of the mixed layer, exploring the reasoning and the parameterization behind the theories of this important boundary region at the surface of the ocean. Dennis Moore gave a careful account of transient flows in equatorial regions and showed how dynamical conditions on the eastern and western boundaries are satisfied by a superposition of planetary, Kelvin and Yanai waves. Peter Rhines concluded the series with a discussion of topographically induced low frequency motions. At the request of the students Joseph B. Keller gave a lecture on "Solution of Partial Differential Equations by Ray Theory".

Beschreibung: National Science Foundation

Beschreibung: Originally issued as Reference No. 67-54

Beschreibung: In former years some of the research and seminars of the WHOI Geophysical Fluid Dynamics program was concerned with determining the interior structure and motions of stars and galaxies. This year we have focused our attention downward rather than upward and have attempted to learn some things about the earth's interior. Freeman Gilbert's lectures on the inverse problem in seismology discuss one aspect of the geophysicist's attempts to infer some things about the earth's interior from the evidence which is available at the surface. Paul Robert presented a survey of the difference attempts to attribute the earth's magnetic field to dynamo action. Willem Malkus, Raymond Hide and Stephen Childress supplemented Roberts' lectures with seminars. As students of our physical environment all of us were entertained and stimulated by this introduction to the netherworld.

Beschreibung: National Science Foundation

Beschreibung: In March 1971, seven members of the Woods Hole Oceanographic Institution were engaged in a multidisciplinary study of Lake Kivu. This expedition represents part of a long-range program concerned with the structural and hydrographical settings of the East African Rift Lakes and their relationships to the Red Sea and the Gulf of Aden Rifts. The program started in May 1963 with a geophysical study on Lake Malawi (von Herzen and Vacquier, 1967). Several expeditions of our Institution into the Red Sea and Gulf of Aden area in 1964, 1965 and 1966 (Degens and Ross, 1969) provided detailed geological information on the "northern" extension of the East African Rift. And finally our study of last year on Lake Tanganyika c1osed a major gap in the program; it allowed us to out1ine a model on the evolution of a rift which starts with (i) bulging of the earth's crust, (ii) block-faulting, (iii) volcanism and hydrothermal activity, and which has its final stage in (iv) sea floor spreading (Degens et al. 1971). In the case of Lake Tanganyika, only the second stage of this evolution series has been reached, i.e. block-faulting. In contrast, the Red Sea and the Gulf of Aden had already evolved to active sea floor spreading, almost 25 million years ago. Somewhere along the line between Lake Tanganyika and the Gulf of Aden must lie the "missing link" of this evolution series. Lake Kivu, almost 100 miles to the north of Lake Tanganyika is situated at the highest point of the Rift Valley and is surrounded by active volcanoes and geothermal springs. As recently as 1944, lava flows reached the lake shore. This lake was therefore, a natural choice to test our hypothesis on the origin and development of rifts. Furthermore, the occurrence of large quantities of dissolved gases, e.g., CO2 and methane, represented an interesting geochemical phenomenon worthwhile to investigate.

Beschreibung: Supported by the National Science Foundation with Grants GA 19262, GB 20956, and GU 3927; grants from the Petroleum Research Fund of the American Chemical Society PRF#1943A2; and by private research funds of the Woods Hole Oceanographic Institution.

Beschreibung: The first year of the New England Regional Fisheries Management Council has been marked by its experimental aura. Neither the Council nor the various sectors (representatives of the Federal and State agencies, members of the fishing industry, the public at large) were clear as to exactly what they were to do and how they were to do it--except in the broadest, most flexible (ambiguous?) terms. This created certain operational difficulties, and confusion for those whose livelihood was affected by the Council's operation. This latter group, particularly the fishermen, knew little of what went on, save in terms of the 'public facet of the Council--i.e., that portion of the Council's performance which occurred during the monthly meetings which were open to the public and which, supposedly, received public input at that time. This study defines that public face, deliberately avoiding the presentation of any data which was not accessible to the average audience participant, in an attempt to present some of the behavior which all participants demonstrated and which generated responses and reactions on the part of the other sectors. It uses standard anthropological techniques of data gathering and analysis to show the degree to which impression management on the part of all the actors operated in a systematic fashion to produce action, reaction, and counter-action. Particularly emphasized is the communication aspects.

Beschreibung: Prepared with funds from the Pew Memorial Trust and by the Department of Commerce, NOAA Office of Sea Grant under Grant #04-7-158-44104, and the Marine Policy and Ocean Management Program of the Woods Hole Oceanographic Institution; and by sabbatical funding from the State University of New York.

Beschreibung: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June, 1980

Beschreibung: This thesis consists of three papers applying the techniques of time series analysis to geophysical data. Surface wave dispersion along the Walvis Ridge, South Atlantic Ocean, is obtained by bandpass filtering the recorded seismogram in the frequency domain. The group velocity is anomalously low in the period range of 15-50 s, and formal inversion of the data indicates both crustal thickening to 12.5 km and low shear velocity (4.25-4.35 km/s) to depths of 40-50 km. The electromagnetic induction fields at a deep ocean site northeast of Hawaii were used to determine the electrical conductivity of the earth to 400 km depth. Singular value decomposition of the data matrix indicates three degrees of freedom, suggesting source field complications and a two dimensional conductive structure. Inversion of one of the principal terms in the response function shows an abrupt rise in electrical conductivity to 0.05 mho/m near 160 km with no resolvable decrease below this. A model study suggests that moving source fields influence the induction appreciably in the other principal response tunction. A set of piston cores from the northeast Atlantic Ocean are used to construct paleomagnetic time series covering the interval 25-127 kybp. Stratigraphic control is provided by counts of planktonic toraminifera, and empirical orthogonal function analysis shows a significant decrease in sedimentation rate at the interglaciai/glacial transition. The sediments are magnetically stable and reliable relative paleointensity measurements could be obtained. Spectral analysis of the directions reveals a predominant 10 ky periodicity and no dominant looping direction.

Beschreibung: I was supported for the early parts of this work by a NSF Graduate Fellowship. The Walvis Ridge study was supported by the WHOI Education Office and the Defense Advanced Research Projects Agency. The induction study was funded by the NSF under grants OCE74-12730 and OCE77-8633, and by the WHOI Ocean Industries Program. The paleomagnetic study was supported by NSF contracts OCE77-82255 and ÖCE79-19258.

Beschreibung: Fish and fishermen appear to be in a serious decline in New England. The haddock are overfished, inshore herring stocks are depleted, yellowtail flounder and lobster are scarce. The popular image is of grizzled fishermen, their boats chipped, scarred, old-fashioned hulks of wood tied up two and three abreast along the rotting wharves and piers of New England's depressed port towns. In this research project, we wanted to determine the state of the New England fishing industry and to propose acceptable methods for the management of the fishery. During our early discussions with the fishing industry people, we mentioned that we were interested in limited effort programs as they might be applied to New England fishermen. We carefully, and probably tediously, explained the "theory of limited effort" and we were generally thought to be daft. We were told we had things backwards--that the fishing industry needed more fish, more men, more boats - and that the way to accomplish this was to get a 200-mile fishing limit and kick the foreigners out. One of these wishes has come true - in the spring of 1976, P.L. 94-265 established a 200-mile fishing zone off the United States, with regional management councils to make management plans and allocate the resources first to United States fishermen, with surpluses to foreign fishermen.

Beschreibung: Prepared with funds from the Pew Memorial Trust and by the Department of Commerce, NOAA Office of Sea Grant under Grant #04-5-158-8 and Grant #04-6-158-44106, and the Institution's Marine Policy and Ocean Management Program.

Beschreibung: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September, 1975

Beschreibung: The Mid-Atlantic Ridge is one of the most well known and yet poorly understood spreading centers in the world. A detailed investigation of the Mid-Atlantic Ridge crest near 37°N (FAMOUS) was conducted using a deeply towed instrument package. The objective was to study the detailed structure and spreading history of the Mid-Atlantic Ridge median valley, to explore the roles of volcanism and faulting in the evolution of oceanic crust, and to study the morphologic expression and structural history of the zone of crustal accretion. In addition, microearthquake surveys were conducted using arrays of free-floating hydrophones. The most recent expression of the accreting plate boundary in the Famous Rift is an alternating series of linear central volcanoes and depressions 1.5 km wide which lie within the inner floor. This lineament is marked by a sharp maximum in crustal magnetization only 2-3 km wide. Magnetic studies indicate that over 90% of the extrusive volcanism occurs within the rift inner floor, a zone 1 to 12 km wide, while volcanism is extremely rare in the rift mountains. Volcanoes created in the inner floor are transported out on, block faults, becoming a lasting part of the topography. Magnetic anomaly transition widths vary from 1 km to 8 km with time and appear to reflect a bi-stable median valley structure. The valley has either a wide inner floor and narrow terraces, in which case the volcanic zone is wide and magnetic anomalies are poorly recorded (wide transition widths); or it has a narrow inner floor and wide terraces, the volcanic zone is then narrow and anomalies are clearly recorded (narrow transition widths). The median valley of any ridge segment varies between these two structures with time. At present the. Famous Rift has a narrow inner floor and volcanic zone (1-3 km) while the south Famous Rift is at the opposite end of the cycle with a wide inner floor and volcanic zone (10-12 km). Over 95% of the large scale (〉2 km) relief of the median valley is accounted for by normal faults dipping toward the valley axis. Normal faulting along fault planes dipping away from the valley begins just past the outer walls of the valley. Outward facing normal faulting accounts for most of the decay of median valley relief in the rift mountains while crustal tilting accounts for less than 20%. The pattern of normal faulting creates a broad, undulating horst and graben relief. Volcanic features contribute little to the large scale relief, but contribute to the short wavelength (〈2km) roughness of the topography. Spreading in the Famous area is highly asymmetric with rates twice as high to the east as to the west. At 1.7 m.y.b.p. the sense of asymmetry reverses in direction with spreading faster to the west, resulting in a gross symmetry when averaged through time. The change in spreading asymmetry occurred in less than 0.15 m.y. Structural studies indicate that the asymmetric spreading is accomplished through asymmetric crustal extension as well as asymmetric crustal accretion. Spreading in the Famous area is 17° oblique. Even on a fine scale there is no indication of readjustment to an orthogonal plate boundary system. Spreading has been stably oblique for at least 6 m.y., even through a change in spreading direction. Magnetic studies reveal that the deep DSDP hole at site 332 was drilled into a magnetic polarity transition, and may have sampled rocks which recorded the earth i s field behavior during a reversal. The presence of negative polarity crust within the Brunhes normal epoch in the inner floor has been determined, and may be due to old crust left behind or recording of a geomagnetic field event. Crustal magnetization decays to lie of its initial value in less than 0.6 m.y. The rapid decay may be facillitated by very intense crustal fracturing observed in the inner floor. Microearthquake, magnetic and structural studies indicate that both the spreading and transform plate boundaries are very narrow (1-2 km) and well-defined for short periods, but migrate over zones 10-20 km wide through time.

Beschreibung: MapTool is an interactive computer program for the display of common marine geophysical data. At present, the program displays isolines, color-filled contours, navigation tracklines, and navigated scalar values in a variety of styles. A variety of map projections are supported. This document describes the basic requirements for running the MapTool program, for creating various displays, and generating hard copy output. The supported data file formats are described. All of the options, displays, menus, and windows are documented.

Beschreibung: Funding was provided by the Office of Naval Research under Grant N00014-90-J-1621.

Beschreibung: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution August, 1971

Beschreibung: An experimental investigation of the different flow regimes in a rotating source-sink annulus is described. Both the steady and transient velocities are measured over a large range of Ekman Reynolds number and Rossby number. Differing probe configurations are used to investigate the corresponding motions in spatially separated regions of the annulus. The steady interior circulation field exhibits a strong dependence on the imposed flux values. The non-dimensional circulation increases with radius over a certain radial range for higher system Rossby number. The observed profile changes are related to the existence of an unstable Ekman layer at some inner radial position. The thickness of the observed Ekman layers is typically 85% of the theoretical scale height. For higher local Reynolds number (ReL), the thickness is generally much smaller. The width of the sidewall boundary layer adjacent to the sink increases with larger system Rossby number. Adjacent to the source, the radial boundary layer is wider than that at the sink wall. Observed oscillations are separable into three types. For ReL 〉 50, instability waves are observed in the Ekman layer flow. In the same Re range, inertial oscillations are detected in the interior region of the annulus. The observed inertial wave frequency at differing radial positions is explained by incorporating Doppler shift corrections and taking account of the steady circulation profiles. The radial wavelength of the inertial waves corresponds to the length of the Class A Ekman layer instabi1ity. For small values of Re and local Rossby number, an axisymmetric disturbance, with a characteristic frequency slightly greater than therotation rate, is observed at the outer radial positions.