Wind patterns in the Pacific Ocean fluctuate seasonally, annually, and decadally, resulting in changes in the dispersal of volcanic smog (vog) across the Hawaiian Islands. A variety of synoptic-scale weather patterns can affect the Islands, creating variability in the direction and intensity of wind patterns. Recent changes in wind profiles were analyzed to identify possible patterns that could influence and increase the dispersion of vog over time on Hawai’i Island and the other Hawaiian Islands to the northwest. Historically, Northeast Trade Winds prevailed for much of the year, shifting vog into the Pacific Ocean southwest of Hawaii and away from the state’s principal population centers, but Northeast Trade Winds have shown a 20+% reduction over the past several decades. An increase in the southerly source of prevailing wind increased the frequency and intensity of vog and its impacts on the environment and health and well-being of people across the Islands.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Meteorology and Physical Oceanography, 1981. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 219-224. / by John Richard Gyakum. / Ph.D.

Severe weather outbreaks are fairly common events that occur multiple times a year. Many studies have attempted to define and quantify these outbreaks, however, no work has been done to directly relate synoptic-scale processes to outbreak intensity using the N15 ranking index. It is believed that a statistically significantly strong relationship between outbreak severity and quantified synoptic-scale parameters exists and can be utilized to predict the severity of an upcoming outbreak using the N15 ranking index. Utilizing the NCEP-NCAR Reanalysis dataset, synoptic-scale variables were chosen and standardized into domains created from areal coverages. A series of tests were completed, including stepwise regression, principal component analysis, and a bootstrap cross-validation method to find the most significant variables and best domain size. The findings from this study suggest that synoptic-scale processes do not have a strong relationship to severe weather outbreak intensity and that future work would be necessary.

This dissertation is intended as an exposition of the examples and precepts of prayer in the life of Jesus, as recorded in the four Gospels

High-Shear Low-CAPE (Convective Available Potential Energy) (HSLC) Tornado Outbreaks (TOs) are a specific subset of TOs that occur each year, primarily East of the Rocky Mountains. This study looks to define HSLC TOs with the use of quartiles of the most supported shear and CAPE measure, create a climatology of HSLC TOs, and to give a better description of the synoptic-scale patterns associated with HSLC TOs. Statistical analysis of quartiles and inner quartile range (IQR) were conducted to see which is the best measure. Ultimately, Mixed-layer CAPE (MLCAPE) and 0-3km shear were used due to past support and were used to define HSLC TOs. Bootstrapping was conducted, and compositing was created for each of the five regions. Bootstrapping between some regions showed statistical significance, and some of the composites matched up closely to what was seen in past HSLC research.

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The bulk of synoptic weather type research related to urban climate focuses on human health impacts; however, recent studies have begun to quantify urban heat island (UHI) magnitudes by weather type, or air mass classification. This study presents an analysis of UHI intensity through synoptic-scale air mass persistence during the spring season for four UHI-prone United States cities. Historical daily weather types for Birmingham, Alabama; Charlotte, North Carolina; Louisville, Kentucky; and St. Louis, Missouri were extracted from the Spatial Synoptic Classification database for 40 years from 1980 through 2019. Daily minimum surface air temperature data were downloaded from the Global Historical Climate Network to compute UHI. The historical daily weather type data were converted into a record of persistence, or the length of consecutive days that a synoptic weather type was in place at each location. A descriptive climatology of SSC weather types and UHI at each location was constructed before UHI magnitudes were segregated by day of persistence and examined for differences in intensity. Climatologically, the four urban areas experienced an increase in warm weather types at the expense of cool weather types throughout the study period. Specifically, the persistence of moist tropical weather types increased at a statistically significant rate at Birmingham, Charlotte, and Louisville, consistent with the theorized northward migration of the mid-latitude jet stream. Also evident is a statistically significant increase in UHI frequency and intensity at Birmingham, Charlotte, and Louisville during the study period. Results show that the moisture character of a weather type is an important differentiating factor in UHI intensification, as the mean UHI was found to increase with the persistence of dry weather types and decrease with the persistence of moist weather types, presumably reflecting differences in radiational heating and cooling with atmospheric moisture content. The most intense UHIs and the largest UHI magnitude increase by day of persistence are associated with dry weather types, which have become more frequent since 1980. The findings suggest that larger magnitude UHIs may become more common in the future should dry weather type persistence continue to increase. Higher urban temperatures put human health at risk due to a well-linked relationship between heat and mortality and morbidity rates. The effects of heat are cumulative; the more common persistent, oppressive days become, the larger the impact. / Master of Science / Most of the research related to variation in the warmth of an urban area relative to the surrounding rural area, or the urban heat island (UHI) effect, under varying air mass conditions (temperature and humidity) has focused on human health impacts. This study examines UHI intensity through regional-scale air mass persistence during the spring season in four UHI-prone United States cities. Historical daily air mass conditions in the form of weather types for Birmingham, Alabama; Charlotte, North Carolina; Louisville, Kentucky; and St. Louis, Missouri were downloaded from the Spatial Synoptic Classification database for the 40 years from 1980 to 2019. UHI values for each urban location were calculated using daily minimum air temperature data from the Global Historical Climate Network. A descriptive climatology of weather types and UHI magnitude at each of the four urban locations established long-term means and trends before analysis of UHI intensity through varying weather type residence times, or persistence. Time series analyses align with previous indications of an increasing persistence of weather types and an increase in the frequency of warm weather types at the expense of cool weather types during the spring season. An increase in both UHI frequency and intensity occurred through the study period at Birmingham, Charlotte, and Louisville. The mean intensity of the UHI was found to increase with the persistence of weather types of low humidity and to decrease with the persistence of moist weather types. The largest mean UHI and the largest UHI magnitude increase by day of persistence are associated with low humidity weather types, which have become more frequent since 1980. The impacts of heat are cumulative; persistently elevated temperatures are detrimental to human health.

This work attempts to relate global teleconnections, through physical phenomena such as the El Nino-Southern Oscillation (ENSO), Artic Oscillation (AO), North Atlantic Oscillation (NAO), and the Pacific North American (PNA) pattern to synoptic-scale weather patterns and precipitation in the Roanoke, Virginia region. The first chapter describes the behavior of the El Nino-Southern Oscillation (ENSO) by implementing non-homogeneous and homogeneous Markov Chain models on a monthly time series of the Troup Southern Oscillation Index (SOI), a sea level pressure based index. Meanwhile, in the second chapter the author has related or an attempt has been made to relate global teleconnections (through ENSO and AO) to a synoptic scale, station-centered set of weather types in order to assess trends in precipitation. The final portion of this work describes spatial variability of seasonal precipitation in southwestern Virginia in a context that incorporates global teleconnections (through AO, PNA, NAO, and ENSO) and frontogenesis. It was found that the Markov property can be used to describe and predict the monthly evolution of ENSO. Also evident is an increased probability of a wetter spring in the Roanoke region when El Nino combines with the negative phase of the AO during the previous winter. Meanwhile, Roanoke winters subsequent to a fall season described by this same El Nino-AO condition are predicted to receive more precipitation than average. This work additionally showed possible trends between frontal-precipitation events in the Roanoke region and global teleconnections. / Master of Science