Observations, Forecast, and Modeling of 0.5-200 Min Infragravity Oscillations in Hale'iwa Harbor Region, Hawai'i

Ph.D. University of Hawaii at Manoa 2016.Includes bibliographical references.The scientific objective of this study is to identify the dominant phenomena, their generation mechanisms, and the corresponding energy pathways that result in 0.5-200 min infragravity (IG) wave energy in Hale’iwa Harbor, North Shore of O’ahu, Hawai’i. We meet these objectives with spectral analysis that is applied to sea level and currents data obtained from historical and recent observations, and high-resolution numerical modeling, inside the harbor and at the coast. Validation and calibration of the model results with harbor and coastal observations have confirmed many of our observational results. Furthermore, analysis of model output from cross-shore and alongshore arrays at several coastal sites has improved our understanding of the generation mechanisms and dynamics of IG waves at the coast; and, detailed maps of energy, coherence amplitude, and coherence phase at the coast and inside the harbor, revealed unique standing wave patterns at several IG periods bands. Interestingly, the greatest observed variance was found to be in different period bands for sea level and currents; ~5-15 min for sea level, and ~3-8 min for currents. When SS forcing is non existent, we observe a suite of coastal and harbor modes that could potentially be forced in different ways (e.g., wind, internal waves). We find that the coastal modes range between 1~23 min (in agreement with other model studies in that region), and the harbor modes between ~40 sec and ~6 min. The model results further support observations indicating that the harbor’s gravest mode potentially oscillates at ~5-6 min. As the SS forcing increases to high levels, our anticipation was that the energy of the modes would grow linearly, as was observed in similar studies by others. Surprisingly, we find that the energetic spectra is predominantly non-modal with uniform levels across a wide band of IG periods, suggesting that other processes (non-modal) are at least as important. The observed high spectral levels extend from periods of minutes to several hours, corresponding to scales much longer than the gravest coastal mode of 23 min. The overwhelming amount of energy hitting the North Shore coast and the irregularities of the bottom and the coastline, are likely strong factors in this observed response. At periods shorter than ~30 min under strong SS forcing, we obtained abundant evidence of bound IG waves offshore of the SS break point, and dominance of free IG waves within the surf zone. The free IG wave field appears to be mostly composed of leaky waves, but at one site we also found evidence of short-period (∼45-60 sec) low-mode edge waves. Inside the harbor, the IG wave field is free, and could be forced by the leaky or edge waves from the coast. Observational evidence several kilometers from the harbor suggests that a SS- driven setup mechanism drives energetic coastal oscillations at periods from minutes to hours. Modeling results much closer to harbor suggest that such a mechanism could potentially force (T<20 min) oscillations inside the harbor. Overall, the scientific portion of this study suggests that inside the harbor, coastal oscillations may be as important as harbor oscillations. This leads us to the conclusion that, at least for harbors with a similar environment as the one in Hale’iwa Harbor and the North Shore, understanding the dynamics of energetic harbor oscillations requires understanding of the dynamics at the coast. For the practical objective of this study, we developed a forecasting system of energetic 0.5-40 min IG oscillations that result in large sea level amplitudes and strong currents in Hale’iwa Harbor. Observations of sea level offshore of the harbor and sea level and currents inside the harbor are used to determine a statistically-optimal relationship between offshore SS forcing and harbor IG response. Using this we establish transfer functions relating the offshore sea level with the harbor currents. Given an input of sea level forecast at an offshore site, the transfer functions are used to generate a forecast of surge currents inside the harbor. This output is expressed in terms of an index that, compared against threshold levels, provides a sense of the danger levels inside the harbor given a particular forecast of offshore forcing conditions. The threshold levels were determined using two exceptionally strong SS forcing events during which we documented the aftermath inside the harbor. These SS forcing events serve as calibration of our forecast and provide us a good sense of the response inside the harbor given particular offshore SS forcing conditions

Forecasts of Wave-Induced Coastal Hazards in the United States Pacific Islands: Past, Present, and the Future

This paper summarizes the existing coastal hazard forecast methods of PacIOOS, such as wave-induced run-up, by focusing on the critical components that need to be addressed in order to improve these forecasts and make them more accurate and available to broader coastal communities. We then propose that a horizontally, two-dimensional numerical modeling approach method should be adopted for developing future wave-induced coastal forecasts. To reach a future in which real-time two-dimensional model-based forecasts are a reality, we identify existing technologies that could lead to improvements, such as: (i) more accurate, accessible and frequently updated bathymetry and topography datasets; (ii) increased computational and software capabilities; and, (iii) more accurate sea level datasets. These advances, combined with crowdsourced-based model-data validation, will result in faster and more accurate forecasting tools that could greatly benefit coastal communities in need of more efficient risk mitigation programs

Mécanismes immunotoxiques de l'ochratoxine A et exposition de la population libanaise

Ce travail porte sur l'effet immunotoxique d'une mycotoxine alimentaire, l'ochratoxine A. Nous avons montré que l'ochratoxine A induit l'apoptose dans les lymphocytes humains entraînant une perte du potentiel mitochondrial transmembranaire et une activation des caspase-9 et caspase-3. De plus, l'expression de la protéine Bcl-xL diminue en présence de l'ochratoxine A. Cette perte de Bcl-xL est due à une dégradation par le protéasome. Nous avons aussi évalué l'incidence de l'ochratoxine A dans le plasma de la population libanaise ainsi que dans certaines denrées consommées. Nos résultats montrent une contamination des céréales notamment le blé et surtout le bourghul, ainsi que la bière où des concentrations supérieures aux limites fixées ont été retrouvées. Les concentrations d'ochratoxine A retrouvées dans le plasma de la population libanaise étaient plutôt faiblesThe aim of this work was to study the immunotoxic effect of ochratoxin A, a widespread mycotoxin contaminating feed and food. We showed that ochratoxin A induces apoptosis in human lymphocytes triggering the mitochondrial transmembrane potential loss and caspase-9 and caspase-3 activation. Interestingly, Bcl-xL protein expression was decreased by ochratoxin A treatment. Bcl-xL loss was due to its degradation by the proteasome. We also evaluated the occurrence of ochratoxin A in the plasma of the Lebanese population and in different foodstuffs. Our results show that cereals such as wheat and burghul are contaminated, as well as beer where concentrations higher than the fixed limits were found. The mean concentration of ochratoxin A found in the Lebanese population plasma was low.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF