The work reflected in this thesis includes a detailed study of co-flow jet (CFJ) technologies as they are applied to a typical thin airfoil, NACA 6415, at take-off and landing speeds. Numerical analysis and experimental testing were conducted on baseline and co-flow jet airfoils of the same plan form. The CFJ mechanism employs high pressure air injected along the span at the leading edge while a low pressure source removes the same amount of air along the span at the trailing edge. Hence, the net mass flux of the system is zero energy loss is minimized. The jet produced along the upper surface of the airfoil mixes with and excites the free stream flow resulting in increased lift, augmented stall margin, and decreased drag. At certain angles of attack the decreased drag is negative and thrust is produced. The research was comprised of four phases including computational fluid dynamics (CFD) simulations, design and manufacturing of a transformable baseline and adjustable slot size CFJ airfoil, implementation of a CFJ Wind Tunnel Laboratory, and wind tunnel testing. A computational fluid dynamics code, developed at the University of Miami, was used to study flow fields and to obtain analytical results of aerodynamic properties for the baseline and CFJ airfoils. Modeling of both wing shapes utilized the baseline ordinates of a cambered NACA 6415 airfoil. The free stream steady state flow was set to Mach=0.1 to simulate take-off and landing speeds where the co-flow jet mechanism would demonstrate its largest increase in performance. CFD simulations of both models provided aerodynamic coefficients as well as mass flow and jet effect data specifically useful to the CFJ airfoil. The NACA 6415 model used for wind tunnel testing was designed and produced to provide both baseline and CFJ results with adjustable injection and suction slot sizes. Connections for a side-mounted force balance and an air delivery system for the co-flow jet were included in the airfoil model. The design and manufacturing of a wind tunnel test section extension was necessary to provide support for the additional aerodynamic loads induced by the CFJ airfoil and to house various air connections and test sensors. A CFJ Wind Tunnel Laboratory was designed and constructed during the course of the research and included selection of proper air delivery apparatus for the injection and suction air for the CFJ jet. All testing controls and sensor equipment were acquired and installed to obtain various data needed for experimental analysis. Finally, a data acquisition system was designed to consolidate all testing information for ease of use. Wind tunnel testing of the baseline and CFJ airfoils provided the aerodynamic loads and coefficients needed to demonstrate the performance enhancements of the co-flow jet flow control method. Experimental and numerical results were examined to understand the benefits of the co-flow jet as it compares to a similar baseline airfoil. The CFD simulations and experimental measurements agree fairly well. All results indicate that the CFJ flow control method is very effective for a typical thin airfoil with 15% maximum thickness.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology and Physical Oceanography, 1982. / Supervised by Gabriel T. Csanady. Vita. Includes bibliographical references (leaves 221-225).

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1981. / Supervised by Peter B. Rhines. Includes bibliographical references (leaves 210-215).

Tropospheric ozone pollution is a world-wide problem, based on studies reported from locations as diverse as India, Hong Kong, Taiwan, South Korea, Germany, Spain, Greece, Canada, and the United States. Ozone is a serious pollutant in the troposphere due to its adverse effects on the health of plants, and on the respiratory systems, eyes, and mucous membranes of humans. Due to the seriousness of the issue, the ozone problem in the Atlanta, Georgia metropolitan area was investigated. A review of the literature revealed a research deficiency, since no environment-to-circulation analysis of the ozone problem in the Atlanta metropolitan area could be found. Therefore such a study was conducted, in order to determine how high ozone days in Atlanta were related to atmospheric patterns and meteorological variables. Statistical analysis of radiosonde data, and data from eleven air quality monitoring stations in metropolitan Atlanta, for the summer months of 2000-2003, revealed a relationship between high ozone days and both high- and low- pressure patterns, as well as between high ozone days and higher temperature and lower dew point temperature. The data revealed two groups of stations differentiated by geography, and also suggested transport of precursor chemicals as a factor at some stations. This research may assist policy-makers as well as policy-implementers in elucidating associations or mechanisms that can assist efforts to reduce tropospheric ozone concentrations in the Atlanta area.

Intense atmospheric convection associated with the South Pacific Convergence Zone (SPCZ) significantly impacts basin-scale circulation patterns over the Pacific. We explore dynamical processes which foster changes in convection along the convergence zone. These forcings include strong moisture convergence and accumulation of wave energy in the boundary layer, as well as dynamical instability associated with moderate cross-equatorial wind bursts. A focus is applied to observing the dominant modes of variability on synoptic to intraseasonal timescales using a combination of satellite observations and NCEP reanalysis data. Accumulation of energy, due to negative stretching deformation, occurs with both tropical and extratropical modes suggesting that the SPCZ is an artifact of wide ranging modes. Signals of the dominant modes (inferred from fields of outgoing longwave radiation: OLR) are isolated using bandpass filtering techniques, which are then mapped in space and time using Principal Components from Empirical Orthogonal Function analyses. Variability of convective systems in the SPCZ is found to be significantly correlated with changes in the regional Hadley Circulation and the Pacific Walker cell. This co-variability presents the possibility of important teleconnection routes between the tropical West and East Pacific, as well as with the mid-latitude regions of the Northern and Southern Hemispheres. We test these interaction hypotheses by developing composites of the circulation patterns using dates of maximum convection events (regions of minimum OLR) in the SPCZ. Intensities of the large-scale circulations are measured using observations of stream function mass fluxes. Results suggest that deep convection maxima (minima) are associated with an increase (decrease) in the Walker Circulation. It is also illustrated how off-equatorial convection anomalies in the subtropical portion of the SPCZ may induce changes to the Hadley Circulation. Interactions with the zonal (Walker) and meridional (Hadley) circulations appear to have important consequences on the ability for wave energy to propagate through the tropical Pacific atmosphere. Examples include Northern Hemisphere cross-equatorial teleconnections through the Westerly Wind Duct in the upper branch of the Walker circulation and Rossby wave trains in the SPCZ, which may be partially governed by characteristics of the regional Hadley circulation.

Dapeng Bay is located in the southwest coast of Taiwan. It is a cystic shaped shallow lagoon, which has only one entry for exchanging lagoon water with the coastal current. The water quality is depending on the refreshing rate and the mixing level in the lagoon. In order to understand the circulation pattern monthly measurements using an ADP are carried out. Three water quality monitoring stations are constructed for regular online observation of the water quality in the lagoon. The flows are on the west-northwest direction during the flood and toward the west during ebb. Strong currents are observed in the tidal inlet channel. The general circulation patterns are mainly dominated by tide though wind effects can observed from the measurements. This study established a three-dimensional hydrodynamic modeling system using the FVCOM model developed at the U.S. Marine Ecosystem Dynamics Modeling Laboratory for the simulation of Dapeng Bay currents. The study includes the comparison of the recent circulation and the flow fields after broaden of the inlet navigation channel. This will change not only the shape but also dredge the channel deeper. These variations may differ the circulation patterns and the exchange quantities as well. The model results are first compared with the observations for the present situation as calibration. The simulation results for the studies of the changing of the inlet channel will be discussed.

This dissertation uses multiple tools to investigate tropical anvil, i.e., thick, non-precipitating cloud associated with deep convection with the main objectives to provide a climatology of tropics-wide anvil properties and a better understanding of anvil formation, and to provide a more realistic assessment of the radiative impact of tropical anvil on the large-scale circulation. Based on 10 years (1998-2007) of observations, anvil observed by the Tropical Rainfall Measuring Mission (TRMM) Precipitation (PR) shows significant geographical variations, which can be linked to variations in the parent convection. Strong upper level wind shear appears to assist the generation of anvil and may further explain the different anvil statistics over land and ocean. Variations in the large-scale environment appear to play a more important role in anvil production in regions where convection regularly attains heights greater than 7 km. For regions where convection is less deep, variations in the depth of the convection and the large-scale environment likely contribute more equally to anvil generation. Anvil radiative heating profiles are estimated by extrapolating millimeter cloud radar (MMCR) radiative properties from Manus to the 10-year TRMM PR record. When the unconditional anvil areal coverage is taken into account, the anvil radiative heating becomes quite weak, increasing the PR latent heating profile by less than 1 percent at mid and upper levels. Stratiform rain and cirrus radiative heating contributions increase the upper level latent heating by 12 percent. This tropical radiative heating only slightly enhances the latent heating driven model response throughout the tropics, but more significantly over the East Pacific. These modest circulation changes suggest that previous studies may have overemphasized the importance of radiative heating in terms of Walker and Hadley circulation variations. Further, the relationship of cloud radiative heating to latent heating needs to be taken into account for more realistic studies of cloud radiative forcing on the large-scale circulation.

Wave-induced circulation in general coastal environments is simulated by coupling two widely-used finite-element models, namely, a refraction-diffraction-reflection model based on the elliptic mild-slope equation, and a two-dimensional (depth-averaged) shelf-scale circulation model. Such models yield wave-induced current-fields and set-up/down. This involves exploration of some numerical and practical issues, for example, the selection of appropriate boundary condition and grid resolution, numerical errors owing to higher-order derivatives, etc. Computations of the wave forcing from the elliptic wave model, and the wave-induced quantities from the circulation model, are validated with theoretical and published results. The coupled system is then used to simulate the wave-induced circulation in the domains where structures (e.g. breakwater, jetty, etc.) and bathymetric features (e.g. shoal, etc.) are present. In practice, usually an approximate form of the wave-induced forcing is used. This has certain limitations in some application, which have been poorly studied so far. Therefore, here we consider two alternative approaches. The performance of these wave forcing formulations is examined in the regions where the effects of wave reflection, diffraction and focusing are significant. It is observed that the “generalized approach” provides satisfactory results in most situations, provided a grid resolution of L/10 or more is achievable for the wave model domain. The widely-used simplified approach may produce a chaotic pattern of set-up/down and current field in the regions where the wave field is not purely progressive. The third approach ignores the effect of wave diffraction and reflection, and primarily simulates the effect of energy dissipation. Differences up to 25 percent are observed between the modeled current fields obtained with the generalized and the simplified approach. The results suggest that the generalized approach can be used with little practical difficulty and greater reliability.

A growing body of Nd isotope data derived from fish debris and Fe-Mn crusts suggests that the Pacific was characterized by deep-water mass formation in both the North and South Pacific during the Early Paleogene. However, the South Pacific source has not been identified to date. Here we present new fossil fish debris neodymium isotope data from the South Pacific and southern tropical Pacific Ocean Drilling Program and Deep Sea Drilling Project Sites 323, 463, 596, 865 and 869 (paleowater depths spanning 1500 to 5000m) to reconstruct the water mass composition over the time interval ~80 to ~24 Ma. The data indicate a relatively unradiogenic South Pacific water mass composition, and the composition of Nd increases with distance northward. The new tropical Pacific data are consistent with existing records from that region. Analyses of detrital sediment Nd isotopic composition, combined with the dissolved Nd composition recorded by fish debris, suggests that the South Pacific water mass convected in the Pacific sector of the Southern Ocean. We designate this water mass South Pacific Deep Water (SPDW). The Nd isotopic composition of SPDW is more radiogenic than initially hypothesized and the relatively small increase in isotopic composition (from ~-6 to ~-4) during the transit from the Southern Ocean to the tropical Pacific suggests a faster rate of overturning circulation during the greenhouse climate interval than previously thought.

Texte remanié de: Habilitationsschrift--Philosophische Fakultät--Universität Zürich, Wintersemester 1999/2000. / Bibliogr. p. 340-360. Index.