M.S. - Meteorology

Permanent URI for this collectionhttps://hdl.handle.net/10125/2099

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The relationship between the persistent winter cloud zone and the jet stream in the tropical Southwest Pacific
(University of Hawaii at Manoa, 1971) Osborn, Hayward A. L.; Meteorology
The strength of the sub-tropical jet stream in the south-west Pacific has been rather a mystery. By performing a scale-analysis of the equations of motion simplified equations for synoptic scale motions in the tropics are derived. This allows the determination of vertical velocity, and thus a study of the kinetic energy processes can be made. For the case considered it is found that there is kinetic energy generation within a cloud zone to the north of the jet stream. This energy is transported aloft and southwards towards the jet stream. It is suggested that such a process is partially responsible for the maintenance of the jet stream.
The sequence of meteorological events at Canton Island during the 1972-1973 El Niño cycle
(University of Hawaii at Manoa, 1975) Morris, Victor Franklin.; Meteorology
This study analyzes meteorological conditions at Canton Island during the 1972-1973 El Nino Cycle. Heavy rains first appeared in April 1972, and monthly totals exceeded nine inches or more from October 1972 to March 1973. Conditions returned to normal in
A study of Hawaiian and Line Islands rainfall
(University of Hawaii at Manoa, 1976) Meisner, Bernard N.; Meteorology
This report can be considered as yet another installment in what will probably be a never-ending study of precipitation in the vicinity of the Hawaiian and Line Islands. It began as an attempt to update an excellent study conducted by Solot (1950). Althou
Synoptic regimes associated with recent floods in the Rewa
(University of Hawaii at Manoa, 1976) Krishna, Ram.; Meteorology
The relevance of flooding in the Rewa River Basin to the economy of Fiji is reflected in the two recent, Government-initiated, predominantly hydrological investigations relating to the Basin. Identification of synoptic patterns and related satellite obser
A technique for estimating tropical open ocean rainfall from satellite observations
(University of Hawaii at Manoa, 1974) Kilonsky, Bernard John.; Meteorology
The purpose of the study was to obtain accurate estimates of tropical open ocean rainfall from satellite observations. The approach used was the development of a procedure for extracting (approximately one month of data per person per week) highly reflect
Cross-equatorial interactions in the development of a winter typhoon: Nancy 1970
(University of Hawaii at Manoa, 1974) Guard, Charles P.; Meteorology
The purpose of this study is to examine the formation and development of a winter typhoon (Typhoon Nancy: February 1970) and to determine whether significant differences exist between her formation and development and that of "seasonal" typhoons. Particul
A Radar-Based Climatology of Thunderstorms in Hawai‘i
(University of Hawaii at Manoa, 2018-08) Ballard, Robert A.; Meteorology
While relatively infrequent, hazards related to severe convection in Hawai‘i do occasionally occur. Our understanding of these events can be improved by using algorithm data from the Weather Surveillance Radar-1988 Doppler (WSR-88D) to help build a spatial, temporal, and intensity climatology which eliminates population density and diurnal sampling biases. Radar can also expand the climatological area by approximately 17 times over that offered by land-based reports only. Surface and upper air observations and storm reports are used to validate the radar algorithm output. Parameters and indices from sounding data at Līhu‘e are compared to observed thunderstorms, as well as to output from the Maximum Estimated Hail Size (MEHS) and Tornado Vortex Signature (TVS) algorithms, to establish values significant for the occurrence of these events. The data show that greater instability is typically needed to support thunderstorms in Hawai‘i, approximately double that found for similar events over the continental United States. MEHS values greater than 32 mm appear to indicate a higher risk of severe hail in Hawai‘i, and these occur within radar range on average every 5.5 days per year. MEHS values likely to be associated with supercells and very large hail occur within radar range about 1.5 day per year. Most TVSs in Hawai‘i are associated with delta-V values of <30 m s-1, but values ≥ 45 m s-1 (known to be associated with strong tornadoes) have been observed. The results presented here should help forecasters to better evaluate the risk of these rare but important events.
A Bioinformatics Approach to Finding Transcriptional Regulatory Motifs in Bacteria
(University of Hawaii at Manoa, 2016-05) Takebayashi, Taryn
Differential RNA sequencing has made it possible to determine the transcription start sites (TSS) for many of the genes in a genome. By using the TSS information, this study aimed to take advantage of the relatively simple transcriptional organization in bacteria and determine potential transcription factor binding sites for the cyanobacterium Anabaena sp. PCC 7120. By revealing shared sequences adjacent to known TSS, shared TFBS and unique TFBS were identified. This may make this set of computer applications useful in determining which genes in a given dataset are possibly transcriptionally coregulated. This project made use of the transcriptional map of the cyanobacterium Anabaena sp. PCC 7120 in order to narrow down the areas of the bacterial genome that may contain TFBS. The utilization of transcription start sites in locating TFBS is an additional unique feature of this study. This study culminated in tutorials (as shown in the Appendices) covering the programming involved in this project that may help biology students to begin writing their own computer programs.
Large-Scale Weather Patterns Favorable for Vog Occurrences on Oahu, Hawaii
(University of Hawaii at Manoa, 2015-12) Tofte, Kristine
Kilauea Volcano is one of the most active volcanoes in the world, and its two vents (Halemaumau and Puu Oo) release more sulfur dioxide (SO2) than major power plants. During the time of this study (April 2009 – December 2014), the two vents released approximately 3,700 tons of SO2 per day. Within the atmosphere, the SO2 is oxidized and converted to sulfuric acid aerosols through reactions with OH radicals and H2O molecules in clear sky and cloud reactions. This sulfuric aerosol is commonly referred to as volcanic smog (vog) in Hawai'i. During prevailing trade winds conditions, the vog emitted from Kilauea volcano is advected towards the southwest of the Big Island of Hawai'i. However, when winds shift to a southeast or southwest direction, then vog can be carried up the island chain affecting all the Hawaiian Islands. This study focuses on the largescale Weather patterns that cause this wind shift and specifically, on conditions that bring the vog to the island of Oahu, the most heavily populated island. In order to identify large-scale weather patterns that bring vog to Oahu, two datasets were used. Firstly, the Hawai'i Department of Health maintains a record of hourly aerosol mass concentrations in size ranges below 10 μm (PM10) and below 2.5 μm (PM2.5). The volcanic plume consists of accumulation mode sulfuric acid aerosols below 1μm in diameter and therefore, the PM2.5 measurements will capture information about vog concentrations. As part of this study, Hawai'i Department of Health PM2.5 measurements were used to identify elevated vog conditions. Secondly, European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis data were used to determine weather patterns occurring prior and during Oahu vog events. As part of this effort, the ERA-Interim reanalysis data, for different weather patterns, were downscaled to a resolution of 3.3 km using the Weather Research and Forecasting (WRF) model. The WRF output was run in the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to produce both trajectory and concentration plots. The HYSPLIT model allowed for a visual representation of how the vog plume follows the large-scale wind patterns. Data from April 2009 throughout 2014 were analyzed and the total number of vog days was found to be 101. These 101 vog days were the result of 57 distinct vog events lasting from hours up to four days. The 57 events were further categorized into three large-scale weather patterns: precold fronts (37 cases), upper-level disturbances (17 cases) and Kona lows (3 cases). The pre-cold front events had variable duration lasting up to four days and it was found that the largest vog concentrations (PM2.5 values) occurred during long duration pre-cold front events.
Conditions Favorable for the Occurrence of Trapped Mountain Lee Waves Downstream of O‘ahu
(University of Hawaii at Manoa, 2015-05) Li, Liye
The purpose of this study is to determine the synoptic conditions necessary for trapped lee wave development over Oʻahu. The study also shows that the high-resolution mesoscale numerical models could possibly provide valuable numerical guidance for the onset, development and dissipation of trapped lee wave events in Hawaiʻi. The occurrence of trapped lee wave clouds is possible in Hawaiʻi, especially downstream of the island of Oʻahu. The Koʻolau and Waiʻanae mountain ranges of Oʻahu are oriented NW-SE. The pre-frontal southwesterly wind in winter has a large wind component perpendicular to these mountain ranges. With the presence of an inversion aloft, trapped lee waves may occur during the wintertime. In the summer time, northeast trade wind is persistent and trapped lee wave event is relatively rare. In this study, environmental conditions related to the development of three trapped lee wave events (27 January, 2010—TRAP1; 24 January—TRAP2, 2003; 26 January, 2014—TRAP3, 25 August, 1977) are analyzed using soundings, charts, satellite images. The available model input datasets for the summer case in 25 August, 1977 is ERA-40 in the resolution of 2.5⁰×2.5⁰, which is not enough to simulate high-resolution model in 1-km. With input analysis datasets in the resolution of 1.25⁰×1.25⁰, the three wintertime events are successfully predicted by the high-resolution WRF model. Among them, TRAP1 and TRAP2 are initialized using the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), and TRAP3 is initialized with NCEP Climate Forecast System Version 2 (CFSv2) output.Results from a WRF model simulation with a horizontal 1-km grid indicate that the trapped lee waves are most significant just beneath the inversion. There are several common factors involved in the occurrence of these trapped mountain wave events: 1) the presence of a well-defined inversion above the ridge tops; 2) abundant low-level moisture; 3) strong low-level winds with Froude Number (Fr) > 1 impinging on the mountain ranges; and (4) wind shear with increasing wind speed with respect to height through the inversion. A strong pre-frontal southwesterly flow is the typical synoptic setting for the occurrence of trapped mountain waves in winter, whereas in the summer months the presence of an upper-level disturbance with easterly winds aloft is a necessary prerequisite. The vertical wind profile is the key element to determine whether trapped lee waves or downslope winds form. None of the trapped lee wave events in winter or summer have a critical level. If a critical level exists between 500 hPa to 300 hPa, and wind decreases with height in the low level, a downslope wind storm or mountain wave may occur instead of trapped lee waves. Sensitivity tests for the 27 January, 2010 case are performed with reduced relative humidity (RH). With lower RH, trapped lee waves have smaller amplitudes and shorter wavelengths suggesting a latent heat release feedback to the environmental flow.
A Culture Based Study of Non-Fungal Heterotrophic Microbial Eukaryotes from Hawaiian Marine Sediments
(University of Hawaii at Manoa, 2015-05) Chaplin, Mark
Non-fungal heterotrophic eukaryotic microorganisms have been cultured from marine sediment samples from Kāneʻohe Bay, Oahu, Hawaiʻi, USA between 2011 and 2014. Of these, several are new to science and represent novel lineages within their respected classes. Phylogenetically and ultrastructurally novel eukaryotes belonging to the Labyrinthulomycetes, Oomycota, Dermocystida (of the class mesomycetozoea), and likely the Bacillariophyceae (diatoms) were among those cultured. Several cultured organisms appear to represent basal members of genera and even classes. Of ten Labyrinthulomycetes cultured, Oblongichytrium sp. KB9/16, and novel Thraustochytriidae spp. KB8, NK55, and NK58 were investigated in terms of cellular ultrastructure, fatty acid production, and carotenoid pigment production. Also from the stramenopile clade, novel oomycete sp. NK401 was studied in the same manner. The polyunsaturated fatty acid profiles and growth characteristics of these organisms indicates they are unlikely candidates for commercial PUFA production. Carotenoid pigment production was variable and uncertain in some instances. The phylogenetic relationships of the Labyrinthulomycetes were extensively analyzed by maximum-likelihood inference and a most likely phylogeny for the class has been established. On the opposite side of the phylogenetic tree of eukaryotic life, an isolate of Corallochytrium limacisporum and a novel member of the order Dermocystida, sp. NK52, were cultured and studied. These organisms are among the closest unicellular relatives of the Metazoa. Other members of the order Dermocystida are important pathogens of humans and animals, and have only been cultivated by infecting cell cultures. It is hoped that NK52 will provide researchers with material for the by-proxy study of the human and animal pathogens that comprise the rest of the order and in the study of the origins of multi-cellular animals. The diatom that NK52 was co-isolated with also appears to be novel based on examination of its frustule morphology. Investigations into the relationship between NK52 and the diatom it was co-isolated with are ongoing, as is the molecular identification of the diatom. Attempted environmental enumeration efforts for Corallochytrium limacisporum and the Labyrinthulomycetes via correlation with cultured organism standards (qPCR) were generally unreliable when applied to sediment samples, and were likely hindered by non-specific binding, amplification of ton-target DNA, and/or other chemical interference. Had the qPCR assay for C. limacisporum withstood scrutiny, it would have indicated an increased presence of C. limacisporum in sediment sampled, compared to estimates from direct plating of sediment samples.
Investigating Atmospheric Rivers Using Global Positioning Systems from Ocean Transits
(University of Hawaii at Manoa, 2015-05) Almanza, Vanessa
An atmospheric river (AR) can be described as a feature within a warm conveyor belt with anomalous total column precipitable water (TPW). The moisture transport from low latitudes to high latitudes within an AR is a major contributor to global water cycle and are often associated with high precipitating and flood events. Close monitoring of ARs is heavily reliant on satellite and models that have poor spatial and temporal resolution for monitoring TPW. Ship-based Global Positioning System (GPS) receivers have been successful in obtaining millimeter TPW accuracy within 100 km from the nearest ground-based reference receiver at a 1 second sampling rate. We extend this capability with a field experiment using a GPS meteorology system installed on board a cargo ship to monitor TPW during AR events over the Eastern Pacific Ocean. In a 14-day cruise the GPS captured TPW spikes >50 mm during the early development of two ARs, which caused flooding conditions for the west coast of California and moderate to heavy rainfall events for Hawaii between the periods of February 3-16, 2014. Comparison between TPW solutions processed using different GPS reference sites provide an internal validation for the GPS TPW estimates in the deep ocean and indicate the errors here are typically less than 5 mm. Land, satellite and model –based observations provide an external validation of 1.65 mm, 6.11 mm and 13.38 mm RMSE, respectively. The zones most heavily trafficked by cargo containers are near the coasts, yet these areas are a challenge for satellite retrievals. Commercial ship-based GPS receivers offer an extremely cost-effective approach for acquiring meteorological observations over the oceans, and can provide important calibration/validation data for satellite retrieval algorithms. Ship-based systems could be particularly useful for augmenting our meteorological observing networks to improve weather prediction and nowcasting, which in turn provide critical support for hazard response and mitigation efforts in coastal regions.
Seasonal evolution of the modes of interannual variability of the South American monsoon
(University of Hawaii at Manoa, 2013-05) Ludert, Alejandro Tomas
This work focuses on the interannual variability of precipitation during the December-January-February (DJF) season and the seasonal evolution of the modes of variability of precipitation from September to May over the South American continent. For this, we use Empirical Orthogonal Function (EOF) and Seasonal reliant EOF (S-EOF) analysis as well as area averaged precipitation anomalies over Eastern Brazil to characterize precipitation variability over the region. Using EOF analysis we find that the dominant mode of DJF variability of interannual and longer time scales is characterized by strong precipitation anomalies over Eastern Brazil and anomalies of opposite sing over South East South America (SESA) and the western part of the Amazon Basin. This mode is referred to as the Continental tripole mode in this study. This dominant DJF mode is a robust feature across all datasets examined and shows little correlation to SST anomalies. The second DJF mode is characterized by a meridional dipole of precipitation anomalies forced by ENSO SST anomalies. During SON the first two leading modes of precipitation variability are related to Pacific SST anomalies. The first SON EOF mode is related to SST anomalies over the central Pacific and is characterized by a dipole of precipitation between SESA and the South Atlantic Convergence Zone (SACZ). The second SON EOF mode is related to eastern Pacific SSST anomalies and is characterized by a meridional dipole of precipitation over South America. During MAM, the dominant EOF mode is the meridional dipole mode forced by ENSO SST anomalies. Due to the weak relationship between the DJF ontinental tripole mode (EOF 1) of variability and contemporary SST anomalies, Grimm and Zilli (2009) proposed that precipitation anomalies during the previous SON season may, via local surface-atmosphere interactions, be a contributing factor to the development of this DJF mode. This hypothesis is based on the significant correlation between the time series of the SON EOF 1 and the DJF EOF 1. This type of relationship is only weakly or not at all reproduced by the datasets used in this study.
Numerical simulations and observations of airflow through the Alenuihaha Channel
(University of Hawaii at Manoa, 2013-05) Hitzl, David Eugene
The characteristics of airflow in the coastal waters of the Hawaiian archipelago, with special emphasis on the Alenuihaha Channel, are examined using a combination of observations and model simulations from the Advanced Research Weather and Forecasting Model (WRF-ARW). General features of airflow related to interaction with the archipelago, including seasonal and diurnal changes, are presented using historical data from the QuikSCAT satellite, various buoys and sounding data gathered in the Alenuihaha Channel. Verification of the WRF model's performance is achieved through comparisons of several years of buoy data with the respective years of a WRF model hindcast. Special attention is paid to the Alenuihaha Channel, the site of two historical buoys, where a notable acceleration of winds occurs in conjunction with a sinking of the trade wind inversion. Model support for the existence of accelerated winds, a lowering of the inversion and a hydraulic jump within the channel are demonstrated. A WRF model case study for July 2005 clarifies the location of the fastest channel winds, their magnitude, degree of deflection and diurnal variations while elucidating the mechanics by which these features develop. Topographical influences of Maui on the airflow through the Alenuihaha Channel are explored by comparing WRF runs with Maui topography with those in which it has been removed. These effects amount to a combination of island blocking/orographic lifting on the windward side and adiabatic descent on the leeward side, which augment the pressure gradient through the channel. Model simulations represent the sinking inversion and hydraulic jump, delineating their respective amplitude and placement.
Eyewall rainfall patterns from aircraft lower fuselage radar images
(University of Hawaii at Manoa, 2013-05) Barnes, Carl Edward
Airborne radar serves as the premier source of rainfall data for tropical cyclones over the open ocean. The eyewall is of particular interest due to the high impact of the conditions associated with this feature. Airborne data from missions into TCs can illustrate rainfall features in eyewalls. Therefore, this study selected and analyzed images that best captured eyewalls from the last two decades. The study developed a scheme to quantitatively analyze the eyewall. The eyewall features examined included the eye area, maximum eye diameter, eye roundness, eyewall area, eyewall completeness, maximum eyewall width, maximum reflectivity value and location, number of local reflectivity maxima, and eyewall mean rainrate. These variables were compared to TC intensity and motion characteristics from the Best Track dataset and the environmental characteristics from the SHIPS dataset.
Eddy-induced poleward migration of westerly jets in an idealized atmospheric global circulation model
(University of Hawaii at Manoa, 2010-12) Scanlon, Kathleen Elizabeth
This thesis work tests the hypothesis that synoptic eddy and low-frequency flow (SELF) feedback may result in the slow poleward migration of a zonal jet. An atmospheric general circulation model (GCM) was integrated without forcing or dissipation under a basic state in each hemisphere consisting of a single, baroclinically unstable, zonally-uniform jet centered on 30° or 45° latitude. For a wide range of jet speeds, the jet was found to sharpen and jump poleward initially, as the result of the rapid development of synoptic baroclinic eddies due to baroclinic instability. After the end of the initial eddy life cycles, the jet migrated slowly poleward. A preliminary, diagnostic investigation shows that this second type of behavior is consistent with a hypothesis based on the theoretical framework of the SELF feedback (Jin et al. 2006a). Furthermore, the relationship between the speed of poleward propagation and the ratio of eddy momentum fluxes to the background zonal flow is in good agreement with theoretical predictions. The physics involved may also apply to migrating zonalwind anomalies of the type observed in the simulations of more complex GCMs and in nature.
The diurnal variations of rainfall and winds over Malaysia
(University of Hawaii at Manoa, 2010-12) Richard, Sandra Scholastica
This study focuses on the diurnal variations of rainfall and winds over Malaysia. Data from 35 ground stations, combined with other remote-sensing products, are analyzed. Rainfall distribution has large spatial variations with higher rainfall on the windward side, especially during the winter northeast monsoon season. The timing of the season with heaviest rainfall occurs when the northeast monsoon has the largest impinging angle on the coastal mountain ranges. The driest season occurs during the southwest monsoon season, with low total precipitable water over the area, and when the monsoon trough is farthest to the north over the South China Sea. Land-sea breezes and/or upslope-downslope winds occur throughout the year for most areas. The timing of the diurnal rainfall maximum and horizontal rainfall distributions is closely related to terrain, local winds and the interaction of the diurnally driven winds with the prevailing flow. On the windward side, sea breezes/upslope winds combine with the prevailing flow resulting in a rainfall maximum during the late afternoon due to orographic lifting. On the leeside, sea breezes/upslope winds result in a secondary rainfall maximum during the late afternoon. The afternoon rainfall maximum mainly occurs near the foothills of the mountain ranges and propagates inland during the late afternoon/early evening. Over the northwest coast of East Malaysia, nocturnal rainfall is most significant during the late northeast monsoon season due to convergence of land breezes and the northeasterly monsoon flow. Throughout the year, convergence between land breezes and the prevailing flow or between land breezes from both sides of the coast within the strait results in nocturnal rainfall over the coastal areas. Over the east coast of West Malaysia, land breezes are evident, except during the early northeast monsoon season under strong northeasterlies (7~8 m s-1). During the early northeast monsoon season, nocturnal rainfall is most significant due to the orographic blocking of the strong northeasterly monsoon flow. Flow deceleration of the incoming northeasterly monsoon flow is most significant in the early morning.
Low-level inflow patterns to tropical cyclones as determined with global positioning system dropwindsondes
(University of Hawaii at Manoa, 2010-12) Kelly, Julie Kathleen
Data collected with Global Positioning System dropwindsondes (GPS sondes) in four tropical cyclones (TCs) are analyzed to determine how the low-level inflow varies azimuthally and in thickness. The structure of a developing tropical cyclone is highly asymmetric and is influenced by two key factors: vertical shear of the horizontal wind and storm motion. Composites from GPS sondes were supplemented with aircraft radar and the Hurricane Research Division's H*wind analysis to produce horizontal plan view images of the radial flow at varying heights. Inflow depths were also plotted as a function of latitude and longitude. This study provides evidence that as a TC intensifies, the inflow depth decreases and the inflow becomes more axisymmetric. The vertical structure was found to remain nearly unchanged within a 100 km annulus of the storm center, in the lowest 1 km for the weaker TCs, while the two major hurricanes showed significant changes in the radial speed, depth and azimuthal coverage around the storm center. The wind shear and the storm motion were found to influence maximum inflow location and appear to be correlated with boundary layer asymmetries in the radial flow. This is in accordance with previous studies from Corbosiero and Molinari. The angle between the TC motion and the wind shear vectors appears to influence the magnitude of the inflow velocities. When the TC motion vector lies to the left of the wind shear vector and the angle between them is less than 135 degrees, then both factors predict inflow maxima collocated in the same region.
A nonlinear statistical downscaling approach of ECHAM 5 model data to project heavy precipitation events for Oahu, Hawaii
(University of Hawaii at Manoa, 2011-12) Norton, Chase Warren
The objective of this thesis is to build, calibrate and test nonlinear statistical models in an attempt to find the optimal relationship between large-scale atmospheric variables provided by coarse resolution global models and station specific heavy precipitation data on the island of Oahu, Hawaiʻi. The models will be calibrated using NCEP reanalysis II data and tested with an independent data set for model verification. After the models are adequately calibrated and tested, GCM data are used as input into the calibrated statistical models for the period 2011-2040. A BCa bootstrap resampling method is used to provide 95% confidence intervals of the storm frequency and intensity for all three datasets (actual observations, downscaled GCM output from the present-day climate, and downscaled GCM output for future climate). This provides a method to analyze future heavy precipitation at the station scale and can provide the needed information to best plan and prepare for changes in heavy precipitation events. Results suggest a tendency for increased frequency of heavy rainfall events, but a decrease in rainfall intensity during the next thirty years (2011-2040) for the southern shoreline of Oahu.
The role of the atmosphere in geodetic remote sensing
(University of Hawaii at Manoa, 2011-12) Kealy, John Conleth
Geodetic remote sensing signals inherently contain information about the medium they must pass through, namely the Earth's atmosphere. The information added to such a signal can take the form of unwanted noise, or can be useful, depending on the nature of the observing system. This study focuses on two contrasting approaches to atmospheric interaction with geodetic satellite signals, atmospheric noise reduction in Interferometric Synthetic Aperture Radar (InSAR), and meteorological data acquisition over the ocean using the global positioning system (GPS).

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