Global Environmental Science Theses

Permanent URI for this collectionhttps://hdl.handle.net/10125/60447

The Bachelor of Science Degree Program in Global Environmental Science (GES) is administered by the department of Oceanography in the School of Ocean and Earth Science and Technology of the University of Hawai‘i.

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Age and Growth of the Divine Dwarf Goby Eviota Epiphanes from O'ahu, Hawai'i
(University of Hawaiʻi at Mānoa, 2013) Grant, Reagan; Friedlander, Alan; Oceanography; Global Environmental Science
I examined the age and growth of the divine dwarf goby Eviota epiphanes, a small, cryptic reef fish, in order to determine its role in the nearshore marine ecosystems of Hawai‘i. Age was determined by counting presumed daily increments of transversely sectioned sagittae otoliths from 53 specimens captured on O‘ahu, Hawai‘i between August and November 2012. Post-settlement growth was best represented by the von Bertalanffy growth function with a correlation coefficient of 0.53 and a residual sum of squares of 150.3. From examination of otoliths and counts of presumed daily increments, the mean pelagic larval duration (PLD) was found to be 26.5 +/- 0.22 days (SE) and the estimated maximum age was approximately 60.5 days. The proportion of total lifespan represented by the PLD was 43.8%, which corresponds to 34 days of post-settlement life. Estimated daily natural mortality was 3.6%. The age at sexual maturity calculated from the von Bertalanffy growth function was 40.9 days (or 14.4 days post-settlement). Mean generational turnover was 50.7 days. The rapid growth and short life span of E. epiphanes supports the hypothesis that small reef fishes are an important food source for piscivorous species and therefore plays an important role in the energetics and productivity of coral reef ecosystems.
Internal Waves: Modeling Energy Dispersion at the Ocean's Surface
(University of Hawaiʻi at Mānoa, 2012) Martinelli, Joseph; Carter, Glenn; Oceanography; Global Environmental Science
Using the Princeton Ocean Model, internal waves are generated by forcing waters over three different idealized stratification profiles. One profile is of constant stratification while the other two have moderate pycnoclines near the ocean surface followed by constant stratification at depth. The pycnocline in the two stratified cases is defined by a Gaussian curve with a different maximum value in each case. Building on work done by Gerkema (2001), these cases will be analyzed to determine how the internal wave energy rays interact with the pycnocline. Based on the output from POM, focus will be placed on visually interpreting energy reflections off the pycnocline and the ocean surface. The goal is establish an understanding of potential long distance internal wave propagation in ocean regions with similar stratification.
Identification and Photometry of Candidate Transiting Exoplanet Signals
(University of Hawaiʻi at Mānoa, 2012) Chang, Emily; Gaidos, Eric; Oceanography; Global Environmental Science
Exoplanet detection is important to the science of star and planet formation and the origin of life. There are currently 760 confirmed exoplanets. We investigate late-K to early M dwarf stars for exoplanets because the relatively small size and low luminosity of the stars increase the possibility of detecting smaller, Earth-like exoplanets. For my project, the transit method was utilized in planet detection. First, a list of candidate transiting signals was compiled. Data from 1753 late-K and early M dwarf stars collected by the WASP (Wide Angle Search for Planets) survey were analyzed. The signals from these stars were processed with a transit-hunting algorithm called HUNTER. One thousand and sixteen stars were found to have transiting signals. Each star had up to 5 possible transiting signals for a total of 3946 signals. I imposed a restriction on the signals to reject possible false positives which cut the list from 3946 signals to 1546 signals. The remaining signals were manually screened based on statistical analysis. The result was a list of 77 candidate transiting signals. Next, I completed followup photometry with the Faulkes-North telescope on 18 of the 77 candidate transiting signals. I used ephemeris data from the transit-hunting algorithm to create a list of predicted transit events. I have analyzed data on 18 unique targets across 22 observation times slots. Analysis included the calculation of an optimal aperture radius to use in photometry. A photometric precision of 4.0 x 10-4 has been achieved. With this RMS, I can detect a planet 2.83 times the radius of the Earth. Data from the Kepler Mission was used to predict 1-3 planets should be detected around the Super-WASP late-K and early M dwarf stars. So far, no transits have been witnessed.
Effect of Biochars Varying in Physio-Chemical Properties on Water Holding Capacities of Two Tropical Soils with Contrasting Texture
(University of Hawaiʻi at Mānoa, 2012) Bascunana, Jeremy; Deenik, Jonathan; Oceanography; Global Environmental Science
There is a growing interest in biochar for use in sustainable agricultural production systems. Water management has become a key priority as climate change exacerbates imbalances between water demand and availability. Eight biochars of different properties were applied to two soils with contrasting texture to investigate the effect of biochar on water holding capacities. Two different addition rates were applied, 2% and 4% (w/w), and compared to a zero-biochar control. All biochars showed a significant effect in water holding capacities in both soils. In the sandy soil higher addition rate always led to higher water retention, while in the clayey soil, higher addition rate of some biochars led to decreased water holding capacities. Gasification biochar generally led to the greatest improvements, showing 38.5% and 31.5 % increase in the sandy and clayey soil, respectively. Variable results of some biochars indicated that biochar’s ability to increase water retention also depended on to which soil it was added. No significant relationships were found between volatile matter and ash content of biochars and changes in water retention. More research is needed on surface area measurements to test the hypothesis that water holding capacities are directly related to surface area of biochars.
The Effects of Physical Oceanographic Structure and Processes on Biological Patchiness in the Coastal Ocean
(University of Hawaiʻi at Mānoa, 2010) Timmerman, Amanda; McManus, Margaret; Oceanography; Global Environmental Science
Thin layers are aggregations of plankton that span large horizontal areas and are vertically thin. These layers are important because of their influence on population dynamics, trophic interactions, biological structure, and cycling of elements in the sea. During a 24 hr overnight study off the leeward coast of Oahu, Hawaii, to assess the effects of physical oceanographic processes and structure on thin layers through a mooring array and continuous water column profiling. Thin layers were present in 22% of the shipboard profiles (32 of 148). Sixty percent of the thin layers (23 of 39) were observed when the water column was stratified due to diurnal daily heating (1800 to 2150). When the water column was stratified, the thin layers occurred on a similar isopycnal. Water column stability is important in the formation of thin layers. These findings agree with historical observations of thin layer structures in the coastal waters of the mainland United States and Europe.
The Impact of Hurricane Force Wind Fields in the North Pacific Ocean Environment
(University of Hawaiʻi at Mānoa, 2011) Yildiz, Selen; Businger, Steven; Oceanography; Global Environmental Science
This study analyzes the distribution of hurricane force winds in extratropical cyclones as documented by Quikscat wind data over the North Pacific Ocean from January 2003 through May 2008. Interannual variability and influence of the ENSO cycle are presented. When WAVEWATCH III model forecasts associated with these intense storms are compared with buoy observations over the eastern and central Pacific, it is shown that the model significantly underestimates the large swell events. The case study showed that the wave steepness is larger than the majority of cases where ships were damaged. The winds driving the WAVEWATCH III model are under predicted by NOAA’s operational global weather model, which leads to under prediction of the large waves.
Determining the Molecular Taxonomy of Ciguatoxin Vectors in Hawaiian Waters
(University of Hawaiʻi at Mānoa, 2011) Pang, Bradley; Trapido-Rosenthal, Henry; Oceanography; Global Environmental Science
Ciguatera fish poisoning is a seafood-borne illness caused by the consumption of fish which have ingested and accumulated ciguatoxins. Ciguatoxins travel up the marine food web from primary producers, Gambierdiscus sp, to herbivorous and carnivorous fish that are consumed by humans. In the United States, ciguatera is responsible for the highest reported incidence of food-borne illness outbreaks attributed to finfish and is thought to hold this distinction worldwide. However, little is known about the process of bioaccumulation or the vectors that deliver ciguatoxin to humans. The aim of this study was to gain a better understanding of the species that make up the food web that vector ciguatoxin to humans by more precisely identifying the organisms involved. To this end, molecular taxonomic techniques centered on the cytochrome c oxidase gene were employed to develop phylogenetic trees. Results indicate that a frequently ciguatoxic high-level carnivore in Hawaii’s coral reef ecosystem, the Cephalopholis argus, differs from the type specimen of C. argus that is in the National Center for Biotechnology Information nucleotide sequence database. The COX-1 sequences from various local prey species were also studied and demonstrated the congruence of molecular and morphological data.
High-Rate Anaerobic Digestion Using Carbon Support for Biofilm Immobilization
(University of Hawaiʻi at Mānoa, 2011) Lopez, Ryan; Cooney, Michael; Oceanography; Global Environmental Science
The performance of a three-phase up-flow integrated high-rate anaerobic digestion reactor system utilizing corn cob biochar as biofilm support was characterized at 10 liter total scale on synthetic and food processing derived wastewater at defined hydraulic retention times. Both feeds possessed equivalent feed COD of approximately 16g L-1. Performance was evaluated in terms of COD, TN, TP reduction, as well as methane production rates. Soluble COD reductions of approximately 85% with a methane production rate of 0.89 m3 m-3 d-1 were achieved for digestion of the synthetic wastewater at a HRT of 7.3 days and an organic loading rate of 2.2 kg COD m-3 d-1. Soluble COD reductions of approximately 60% were achieved on food processing derived wastewater for an HRT of 3.0 days and an organic loading rate of 4.93 kg COD m-3 d-1 and a methane production rate of 1.48 m3 m-3 d-1. Combined, these results confirmed that high rate anaerobic digestion can be achieved through use of biochar filled column reactors connected in series and fronted by an initial hydrolysis reactor that buffers the system from disturbances in pH and temperature as well as non-sterile wastewater feed that is infused with natural bacterial flora.
Evaluation of Anthropogenic Impacts on the Flow of Two Coastal Springs in Maunalua Bay, South Shore, O'ahu
(University of Hawaiʻi at Mānoa, 2011) Kennedy, Joseph; Glenn, Craig; Dulaiova, Henrieta; Oceanography; Global Environmental Science
Groundwater discharge has long been known to fringe O’ahu’s south shores as springs and beach seeps, with many examples sporadically described since the early works of Stearns and Vaksvik (1935). Hawaiians have used these freshwater resources for centuries, primarily for creating brackish water environments that formed the setting for many of the fishponds that were found throughout the islands. Coastal development over the years has impacted these unique aquaculture practices and left most in ruin. The road widening project of Kalanianaole Highway in 1993 effectively severed all flow of water from the freshwater conduit that fed one of the last remaining fishponds on O’ahu, Lucas Spring, and allowed an estimated 1 million gallons of groundwater per day to infiltrate into an adjacent sewer line damaged during the construction. The proposed rehabilitation project of the sewer line in 2010 created a unique opportunity to study the possible restoration of groundwater flow to Lucas Spring. Continuous radon measurements combined with a salt mass-balance approach was used to determine groundwater flow rates into the impacted Lucas Spring, as well as in Kanewai Spring, which was selected as a comparison site. Over the course of this study, groundwater discharge to Lucas Spring increased from less than 1 m3 day-1 to ~140 m3 day-1 and the volume of water increased from ~8 m3 to ~190 m3 with no effective change in the nearby comparison spring. Although a spring discharge of 140 m3 day-1 only represents ~20% of the historic flow, it is still a significant improvement over the prior decades’ average flow when the pond was almost completely dry.
Compound Specific Isotope Analysis in Food Web Studies: The Need for Accurate Estimates of Trophic Enrichment Factors
(University of Hawaiʻi at Mānoa, 2011) Hoen, Danielle; Popp, Brian; Oceanography; Global Environmental Science
Ecosystem-based fisheries management strategies require knowledge of trophic relationships. Trophic position (TP) estimates from compound specific nitrogen isotopic analysis of amino acids (AA-CSIA), although promising, have not been thoroughly tested. TP estimates from AA-CSIA require knowing ß, the difference in δ15N values between glutamic acid and phenylalanine in primary producers and ∆, the 15N enrichment at each trophic step or trophic enrichment factor. Values of ß (3.4%o) and ∆ (7.6%o) have been suggested for aquatic environments, however recent observations indicate that ∆ may be variable particularly among elasmobranchs. We determined ∆ values for three species of sharks, sand tiger (Carcharias taurus), lemon (Negaprion brevirostris), and leopard sharks (Triakis semifasciata), and one teleost species, opakapaka (Pristipomoides filamentosus) grown on semi-controlled and well characterized diets for durations ranging from three (Triakis semifasciata) to over five years (Pristipomoides filamentosus). We found the ∆ values for both elasmobranchs and opakapaka were similar and were significantly lower than the ∆ value of 7.6 %o previously reported. These results do not support the hypothesis that urea retention lowers δ15N enrichment values in elasmobranchs. Rather, similar ∆ values may be due to carnivorous feeding strategies in elasmobranchs and teleosts.
Spatial Variability of Sea Level Rise Due to Water Impoundment Behind Dams
(University of Hawaiʻi at Mānoa, 2011) Fiedler, Julia; Conrad, Clinton; Oceanography; Global Environmental Science
Dams have impounded ~10,800 km3 of water since 1900, reducing global sea level by ~30.0 mm and decreasing the rate of sea level rise. The load from impounded water depresses the earth’s surface near dams and elevates the geoid, which locally increases relative sea level (RSL). We computed patterns of dam-induced RSL change globally, and estimated that tide gauges, which are often close to dams, recorded only ~60% of the global average sea level drop due to reservoir building. Thus, RSL in the globally averaged ocean rose ~0.2 mm/yr more slowly than has been recorded by tide gauges, or ~10% slower than the measured rise rate of 1.5-2.0 mm/yr. Relative proximity to dams caused RSL to rise fastest in northeastern North America and slowest in the Pacific. This dam-induced spatial variability may mask the sea level “fingerprint” of melting sources, especially northern (Greenland) sources of glacial unloading.
Experimental Analysis of an Undesirable Crystal Precipitate in a Developmental Carbon Fuel Cell
(University of Hawaiʻi at Mānoa, 2011) Blitz, Ashley; Antal Jr., Michael Jerry; Oceanography; Global Environmental Science
Carbon fuel cells have the potential to generate electricity from biocarbons with a theoretical thermodynamic efficiency of 100%. A higher efficiency in generating electricity will mean that less biocarbons will need to be used to realize the same electricity output. This efficiency and the use of a clean energy alternative can help reduce our consumption of fossil fuels and reduce our carbon emissions. The goal of this project is to determine the chemical composition and formula of an unwanted crystal precipitate being produced from a carbon fuel cell and to determine the thermodynamic properties of the crystals in order to prevent them from forming in the fuel cell during operation. The carbon fuel cell is being developed in the Renewable Resources Research Laboratory at the Hawaii Natural Energy Institute. The chemical composition of the precipitate was determined by thermogravimetric analysis and mass spectrometry by the Hungarian Academy of Sciences. Once the composition was determined, a pressure vessel immersed in a fluidized sand bath was used to determine the temperature and pressure at which the decomposition of the crystal precipitate in solution was observed. The complete decomposition temperature will determine the optimal operation temperature for the fuel cell. The unwanted crystal precipitate was discovered to be potassium bicarbonate. The potassium bicarbonate in solution was shown not to decompose at the same temperature as dry crystalline potassium bicarbonate. However, partial decomposition of potassium bicarbonate into potassium carbonate was observed at 300°C and 320°C. Further work needs to be done to study the kinetics of the decomposition reaction of potassium bicarbonate into potassium carbonate and to determine the equilibrium constant. By studying the kinetics and determining the equilibrium constant, the temperature at which the potassium bicarbonate in solution will completely decompose can be obtained.
Carbon Capture and Storage in Southern California Identifying the Long Term Liabilities
(University of Hawaiʻi at Mānoa, 2009) Coulombe, Danielle; Cooney, Michael; Oceanography; Global Environmental Science
Geologic storage of CO2 from large point sources of emissions is a promising strategy for reducing atmospheric carbon dioxide. Before this technology can be deployed, it is vital to understand the liabilities associated with such storage. GIS modeling was done to identify the risk features and quantify the leakage out of the storage area for four sedimentary basins in Southern California. Faults and fractures, and certain types of well penetrations in the study area were the two main leakage pathways, and leakage was found to be greatest in the Ventura Basin. The results indicate that overall, the Cuyama Basin is better suited to use as a storage site than others in this study. Some refinement of the model is possible, and the potential ArcGIS tools that could be used are recommended.
Biological and Physical Comparison of Cyclonic Eddies in an Open Sea Region and in a Coastal Channel
(University of Hawaiʻi at Mānoa, 2009) Buckley, Shandy; McManus, Margaret; Oceanography; Global Environmental Science
Cyclonic eddies characteristically move cold, salty nutrient-rich water into the euphotic zone. Eddies with a diameter of under100 km (submesoscale) have been much less studied than their larger counterparts, due to the difficulty and expense of tracking, finding, and sampling these comparatively short lived features. The effect of cyclonic submesoscale eddies on biological biomass, measured by fluorescence, was investigated in two areas; the North Sargasso Sea and the Northwest Providence Channel, South of the Bahamas. Two eddies were compared. The North Sargasso Sea eddy, formed as a spin off of a larger nearby eddy, and the Providence channel eddy formed by the interaction wind shear with channel currents. Both surface and subsurface samples to a depth of 600 meters were taken across the eddy centers in single transects. In the center of both eddies current magnitude decreased and current direction changed, while temperature decreased and salinity increased markedly. Fluorescence was most intense near the edges of the North Sargasso eddy, and decreased towards the center. This is a signature of a decaying eddy. In the Providence Channel eddy the fluorescence was heightened across the feature, with high levels on either edge and in the center. Together with a strong increase in salinity and decrease in temperature this pattern is a signature of a mature cyclonic eddy. We also observed enhanced subsurface fluorescence during the entire cruise, both within and outside the eddy structures. Small scale cyclonic eddies were found to effect both physical and biological properties in coastal and oceanic regions.
Changes in Carbonate Sedimentation and the Ocean's Calcium Inventory During the Paleocene-Eocene Thermal Maximum
(University of Hawaiʻi at Mānoa, 2009) Komar, Nemanja; Zeebe, Richard; Oceanography; Global Environmental Science
A simple model of the total carbon inventory, alkalinity and calcium concentrations of the ocean during the PETM (Paleocene-Eocene Thermal Maximum; ~55Ma ago) was developed. The main purpose of the research was to determine the magnitude of change in calcium ion of the deep sea as result of carbon perturbation and increased weathering fluxes. Additionally, we investigate possible implications that such a change would have on boron/calcium and magnesium/calcium ratios, which are used as a proxy for deep water carbonate saturation state and temperature, respectively. It has been observed in sediment cores that during the PETM recovery stage there was enhanced carbonate deposition on the seafloor as a consequence of ocean oversaturation. During the recovery interval, weight percent CaCO3 values were higher than the pre-PETM values, which represents an “overshoot” before the system moved back to steady state. The model includes a weathering feedback in order to simulate the overshoot in carbonate deposition during the PETM recovery phase. We investigated the calcite compensation depth recovery time and calcite saturation state during the recovery phase as well as global ocean bottom water carbonate ion concentration. It was found that under the most plausible scenario the calcium ion concentration change (∆[Ca2+]) was less than 1.4 % and thus it was concluded that the perturbation that took place during the PETM would not jeopardize the validity of the two above mentioned proxies. The significance of understanding the chemistry and processes that took place in the ocean during the PETM lies in the fact that the amount of CO2 that was released into the atmosphere-ocean system during the PETM may be similar to the amount of carbon that humans could potentially emit to the atmosphere in the next several centuries. Thus, comprehension of the processes that occurred during the PETM is important since it provides the opportunity to better predict the future states of the ocean and impacts of anthropogenic CO2 emissions on ocean chemistry.
Fluorescent Microspheres as Proxies for Microorganism in a Deep Subseafloor Tracer Transport Experiment
(University of Hawaiʻi at Mānoa, 2008) Teh, Soo Huey; Cowen, James; Oceanography; Global Environmental Science
There is growing evidence that the subseafloor biosphere extends throughout the immense volume of aging basement underlying the global system of mid-ocean ridge flanks and ocean basins. The umbrella Tracer Transport experiment will be conducted by injecting fluorescent microspheres into a borehole on the flank of Juan de Fuca Ridge and monitoring their arrival at all of the observation boreholes. Microsphere transport rates obtained from this experiment will provide a basis for evaluating the origin of microbes observed in 3.5 million year old sediment-buried basement. In this experiment, the fluorescent microspheres are used as proxies for microorganism. Colloid tracers such as fluorescent microspheres are used to characterize flow rates and preferred flow paths of groundwater, and to gain information about the subsurface transport of microbial pathogens, or other colloidal contaminants. The objective of my thesis is to study the compatibility of these microspheres to the ocean basement environment for the tracer transport experiment, by defining their detection limits within the context of deep basement environment by the detection methods available, studying the characteristics of the microspheres and studying the behavior of colloid tracers through a basalt core. From the detection limit experiment, the minimum concentration detected for the fluorescence microscopy method is 10 microspheres/ filter and for the flow cytometry method is 40 microspheres/ ml. The two methods yield very similar results. Microspheres also clump significantly at high concentrations. The size and fluorescence of the microspheres remain unaffected by light, salinity, temperature (4 to 60 ºC) or pressure (up to 80 bars). The basalt core tested in this experiment did not have connectivity in a scale of cm to m, but in the ocean basement, there will be connectivity in a scale of 10s of m to 1000s of m.
Influence of Sediment Composition on Redox Speciation Within a Hawaiian Coastal Fishpond
(University of Hawaiʻi at Mānoa, 2008) Ricardo, Amanda; Glazer, Brian; Oceanography; Global Environmental Science
In aquatic systems, benthic microbial respiration can have a profound effect on nutrient cycling and overall ecosystem health. Respiration results in the release of bioavailable nutrients as well as series of redox species which can be used as a proxy to identify reduced benthic conditions. He’eia Fishpond, located in Kane’ohe, Hawai’i, is a low energy, shallow coastal system influenced by an influx of both riverine freshwater and marine seawater, as well as by mangrove forests located along its terrestrial periphery. Voltammetric solid-state microelectrodes were used to simultaneously identify and measure changes in redox speciation over time in dark incubations of fine grained to coarse grained sediment core samples taken from the pond. The primary objective of this study was to evaluate the synergy between sediment heterogeneity (i.e., varying grain size, permeability, mineralogy and organic matter content) and sediment redox chemistry. In addition, because coring and relocating sediment samples can lead to confounding effects within sediment cores, voltammetric microelectrodes were also used in a separate experiment to investigate the correlation between sediment core sample conditions and in situ conditions. Redox chemistry profile measurements taken in situ were compared to redox chemistry profile measurements taken from a sediment core sample collected from the same location. The in situ versus core experiment revealed that voltammetric sediment core profiles replicate in situ profiles to within ± 2.5 mm. Sediment cores for the dark incubations were taken from four sites within the pond along a gradient of fine grained to coarse grained sediment with a range of organic matter input. Major sources of organic matter input to the pond include mangrove, macroalgae and phytoplankton. As expected, incubation results showed that sediments most rich in fresh organic matter, those sites in close proximity to the mangroves, are most likely to induce rapid benthic respiration, resulting in increased production of reduced organics. In contrast, sediments containing less organic matter, the sandy sites with more of a marine end member influence, are likely to induce slower benthic respiration and less production of reduced organics. Also, there was indication that sediment at the pond under the greatest riverine influence are iron rich. This is significant because reductive dissolution of iron oxyhydroxides results in the release of both reduced iron and bioavailable phosphorus. Under anoxic sediment conditions, free reduced iron is likely to sequester sulfide via pyrite precipitation and phosphorus that enters sediment pore water is liable to flux upward into overlying waters. Phosphorus diffusion into phosphorus limited overlying water can lead to increased primary productivity and eventually hypoxic water column conditions. Consequently, results of this study, in conjunction with nutrient budget studies and further investigation into end member input, can prove useful when developing future sustainability management practices at He’eia Fishpond.
Temporal and Spatial Analysis of Storm Induced Freshwater Plumes in Southern Kaneohe Bay, Hawai'i
(University of Hawaiʻi at Mānoa, 2008) Bosworth, Kyle; McManus, Margaret; Oceanography; Global Environmental Science
Past research in Kaneohe Bay has shown storm-induced freshwater plumes to be potentially detrimental to the coastal marine ecosystem in terms of drastic salinity reductions, nutrient loading and an introduction of pollutants from urban runoff. Highly episodic rainfall, steep slopes and an increase in urban impervious surfaces are characteristics of the Kaneohe Bay watershed that further exacerbate plume related impacts on the Bay’s ecosystem. This study investigated the temporal and spatial evolution of a storm induced freshwater plume in southern Kaneohe Bay in attempt to further understand plume dynamics in this unique embayment system. Salinity profile data gathered from a six-day shipboard survey were compared to wind data gathered from the HIMB weather station and rainfall data from the Luluku rain gage station. South wind averages were correlated to daily measurements of the offshore extent of the plume and a significant relationship was found. The spatial structure of the surface plume is highly influenced by wind forcing in the southern part of Kaneohe Bay.
A Study of Resonant Periods for Fringing Reefs Worldwide
(University of Hawaiʻi at Mānoa, 2008) Ahrouch, Ghizlane; Becker, Janet; Oceanography; Global Environmental Science
Tropical islands are surrounded by reefs, which are a significant buffer for wave energy. The dissipation of this energy depends on the frequency structure of waves. During tropical storm Man Yi, forcing of resonant motions on a fringing reef at Ipan, Guam was observed. Resonant conditions can be met on reefs when the appropriate wave climate exists to excite the reefs’ natural periods. Fringing reefs have a natural or resonant period, which is proportional to their lengths and inversely proportional to the square root of the water depth. This period is associated with the reef acting as a resonator and allowing a significant amount of wave energy to reach the shore. A literature review was carried out to assess the resonant periods of 53 fringing reefs worldwide. These periods correspond to reefs located in Australia, Hawaii, Guam, Seychelles, and the Virgin Islands. This study is aimed at evaluating fundamental resonant periods of these reefs for present day water levels and for elevated levels due to sea level rise from climate change. The main trend obtained from the results was that the majority of reef resonant periods fall in the infragravity to far-infragravity band. If the resonant periods of the reefs are matched with appropriate wave climate forcing to excite these periods, resonant conditions may be seen and coastal inundation is potentially more likely to happen.
Investigating the Origins of a Mysterious Structure in the Solar Corona
(University of Hawaiʻi at Mānoa, 2013) Jerolmon, Conor; Habbal, Shadia; Oceanography; Global Environmental Science
White light images of the solar corona, captured during the July 11, 2010 total solar eclipse, revealed a unique structure present within the corona at the time of the eclipse. We investigated the origin and evolution of this structure and examined a possible relation to a coronal mass ejection (CME) event. We used satellite data, including full disk images from AIA and SWAP and coronagraph images from LASCO, to develop a time sequence of events prior to and following the eclipse. We found that this structure did not appear to be tied to a CME, but appeared to be material lifted and suspended at a height of approximately two solar radii. This unexpected result demonstrates the continued necessity of eclipse observations as a means of observing a region of space not currently covered by satellites.

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