Extreme precipitation in Illinois contributes to impacts across diverse landscapes, posing threats to agriculture in rural areas and infrastructure in urban centers. Previous studies have reported an increase in the frequency of heavy precipitation in the region and projected its amplification under climate change. However, these findings are often characterized by inconsistent and/or inappropriate approaches for estimating historical trends and their significance and often lack process-based understanding regarding future changes in extreme event climatology. This study aims to obtain robust regional extreme precipitation trends and relate those trends to large-scale circulation and humidity. The climatology and trends of daily extreme precipitation are established by applying a peaks-over-threshold approach to the newly developed NOAA NCEI nClimGrid-D dataset which includes daily precipitation totals at 5-km resolution. For trend estimation, we use Theil-Sen estimation with three approaches designed to emphasize correction of inflation in the significance of the estimated trends: (1) a “naïve” approach in which we simply consider the direct output of the Theil-Sen method and assess significance using a traditional Mann-Kendall test, (2) an approach based on a modified Mann-Kendall test to account for serial autocorrelation in the assessment of significance, and (3) an approach that also controls for the false discovery rate associated with a large number of tests by considering field significance. To relate these trends to large scale drivers, a multivariate self-organizing map is constructed based on standardized 500 mb geopotential height and 850 mb specific humidity obtained from the ECMWF ERA-5 reanalysis dataset. We use a Monte Carlo experiment to identify weather types most associated with extreme precipitation in the area. Temporal and spatial characteristics of the identified weather types are then analyzed to better understanding their role in changes in the frequency of extreme precipitation events across the region. As expected, the results indicate a stark contrast between the naive and more complex approaches for significance testing, where controlling for autocorrelation and test multiplicity reduces the spatial extent of significant trends across all extreme precipitation thresholds. Extreme precipitation in Illinois is found to be associated with a small number of specific weather types characterized by distinct patterns of geopotential height and humidity. Furthermore, the weather types most frequently associated with extreme precipitation are increasing in frequency, suggesting that changes in atmospheric circulation related to moisture transport and convergence are a major contributor to changes in extreme precipitation in Illinois.

No description available.

The goal of the thesis is to trace the sequence of materials of different origin in the synoptic Gospels through stylistic features. The question is whether an author's style is typical in the way it employs syntax. Using syntax, the thesis tests whether a sample can be correctly associated with one author, rather than incorrectly associated with another author. 'Syntax,' in this thesis, quite specifically intends 'an assessment of a very broad range of syntax.' The thesis reviews the literary debate over the 'synoptic problem,' finding that Luke knew and depended the triple tradition known to Mark. Luke did not know or use the unique parts of Mark. This set of materials, then, can be used to test whether syntax indicates a similar relationship. Regarding the literature on style in authorship attribution, the thesis develops principles for measuring style through syntax, and compares the distribution of the occurrence-the 'weighted sum of the logs of the ratio'--of syntax in each of three blocks of text. Such a distribution associates a reference block of text with the correct distribution from the distributions in two alternative texts offered. That is, a reference block drawn from the editorial layer in Mark proves to be closer to the remaining editorial layer in Mark (which is correct), than it proves to be to the editorial layer in Luke (which would be incorrect). This is at least a first step towards using this method with sources that appear in New Testament documents, even when they are small or fragmentary. The thesis then applies such an analysis to one of the clearest sources in the synoptic Gospels, namely, the 'triple tradition' as presented by Luke. The analysis is congruent with the results of literary criticism. This supports the idea that syntax can discern or define a source, and so it can help us understand more about the evolution of the New Testament. Nevertheless, the thesis finds that although Luke knew the 'triple tradition' that Mark used, yet Luke appears not to have fully relied on the version of the triple tradition that we know in, and as edited by Mark. / New Testament Studies / D.Th. (New Testament)

The goal of the thesis is to trace the sequence of materials of different origin in the synoptic Gospels through stylistic features. The question is whether an author's style is typical in the way it employs syntax. Using syntax, the thesis tests whether a sample can be correctly associated with one author, rather than incorrectly associated with another author. 'Syntax,' in this thesis, quite specifically intends 'an assessment of a very broad range of syntax.' The thesis reviews the literary debate over the 'synoptic problem,' finding that Luke knew and depended the triple tradition known to Mark. Luke did not know or use the unique parts of Mark. This set of materials, then, can be used to test whether syntax indicates a similar relationship. Regarding the literature on style in authorship attribution, the thesis develops principles for measuring style through syntax, and compares the distribution of the occurrence-the 'weighted sum of the logs of the ratio'--of syntax in each of three blocks of text. Such a distribution associates a reference block of text with the correct distribution from the distributions in two alternative texts offered. That is, a reference block drawn from the editorial layer in Mark proves to be closer to the remaining editorial layer in Mark (which is correct), than it proves to be to the editorial layer in Luke (which would be incorrect). This is at least a first step towards using this method with sources that appear in New Testament documents, even when they are small or fragmentary. The thesis then applies such an analysis to one of the clearest sources in the synoptic Gospels, namely, the 'triple tradition' as presented by Luke. The analysis is congruent with the results of literary criticism. This supports the idea that syntax can discern or define a source, and so it can help us understand more about the evolution of the New Testament. Nevertheless, the thesis finds that although Luke knew the 'triple tradition' that Mark used, yet Luke appears not to have fully relied on the version of the triple tradition that we know in, and as edited by Mark. / New Testament Studies / D.Th. (New Testament)

No description available.

Glaciers of southwestern Yukon (Canada) and southeastern Alaska (USA) are presently experiencing high rates of annual mass loss. These high melt rates have mainly been investigated with respect to regional temperature trends, but comparatively little is known about how climate variations regulate snow accumulation on these glaciers. This study examines the synoptic weather patterns and air flow trajectories associated with extreme snowfall events in the central St. Elias Mountains (Yukon). The analyses are based on data retrieved from an automated weather station (AWS) between 2003 and 2012, which provide the longest continuous records of surface meteorological data ever obtained from this remote region. The AWS data reveal that 47 extreme snowfall events (> 27 cm per 12 hours) occurred during this period, of which 79 % took place during the cold season months. Air flow trajectories associated with these events indicate that a vast majority had their origin in the North Pacific south of 50°N. Less frequent were air masses with a source in the Aleutian Arc/Bering Sea region and the Gulf of Alaska, and in a few rare cases precipitating air was traced to continental source regions in Western Canada and Alaska. Composite maps of sea-level pressure and upper-level winds associated with extreme snowfall events revealed a frequent synoptic pattern with a low-pressure area centered over the Kenai Peninsula (Alaska), which drives strong southerly winds over the Gulf of Alaska towards the St. Elias Mountains. This pattern is consistent with AWS data wind recordings during snow storms. The most typical synoptic configurations of the North Pacific low-pressure area during extreme snowfall events are either elongated, split, or single-centered, and these situations represent possible seasonal analogues for the different states of the Aleutian Low in the subarctic North Pacific. However, neither the geographical position or intensity of negative sea-level pressure anomalies, nor surface pressure gradients associated with extreme snowfall events are good predictors of the actual snowfall SWE amounts recorded in the central St. Elias Mountains. Estimated snowfall and total precipitation gradients with altitude were confirmed to be much steeper (by up to ~30 %) on the continental side (Yukon), than on the coastal side (Alaska) of the St. Elias Mountains, reflecting the strong orographic division between the continental and coastal marine climatic regimes. Finally, patterns of 500-mb geopotential height anomalies associated with extreme snowfall events at Divide were compared with those associated with unusually high accumulation years in an ice core from the nearby Eclipse Icefield. Results confirm previous findings that associate high snow accumulation winters in this region with the presence of a strong dipole pressure structure between western North America and the Aleutian Low region, a structure which resembles the positive phase of the Pacific North American atmospheric circulation pattern. / De höga smälthastigheter som uppmätts på glaciärer i S:t Eliasbergen (Yukon, Kanada) har främst undersökts utifrån regionala temperatureffekter, men hur storskaliga (synoptiska) klimatvariationer reglerar snöackumulation på dessa glaciärer är mindre känt. Denna analys belyser synoptiska mönster och rekonstruerade banor av luftmassor i samband med extrema snöfall i den centrala delen av S:tEliasbergen. De iakttagelser som gjorts i denna studie bygger på data som hämtas från automatiserade väderstationer (AWS) mellan 2003 och 2012, vilka ger den längst sammanhängande dokumentationen av markmeteorologisk data som någonsin erhållits från denna plats.AWS data avslöjar att 47 extrema snöfall (>27 cm per 12 timmar) inträffade på glaciären under denna period, varav 79 % ägde rum under den kalla årstiden. I samband med dessa snöfall visar det sig att en stor majoritet av luftmassebanorna hade en utgångspunkt i norra Stilla havet söder om 50°N. Mindre vanligt var att luftmassor utgick från Aleuterna/Berings hav och Alaskabukten, och i några sällsynta fall spårades luftmassorna till kontinentala utgångspunkter i västra Kanada och Alaska. Luftmassebanorna från norra Stilla havet visade främst syd-nordcykloniska luftflöden, medan luftmassorna från Aleuterna/Berings hav och Alaskabukten indikerade väst-öst cykloniska luftflöden. Sammansatta kartor indikerade ett likartat synoptiskt mönster av ett lågtryckscentrum över Kenaihalvön (Alaska) för dessa tre marina källområden. Lågtrycket drev starka sydliga cykloniska vindar över Alaskabukten mot S:tEliasbergen och detta vindmönster överensstämde med AWS data. De typiska synoptiska situationerna i samband med extrema snöfall kännetecknades antingen av ett långsträckt, ett delat eller ett litet lågtryckscentrum. Dessa kunde kopplas till olika möjliga tillstånd av det Aleutiska lågtrycket i norra Stilla havet. Studien kunde inte bekräfta att lågtryckscentrums geografiska placering, anomalier av havsnivåtryck eller tryckgradienten starkt reglerade de extrema snöfallmängderna uppmätta från AWS data på studieplatsen. De beräknade nederbördsgradienterna bekräftades vara brantare på den kontinentala sidan (Yukon) än på kustsidan (Alaska) av S:tElias-bergen, vilket återspeglade skillnader mellan den kontinentala och den kustnära marina klimatzonen. Slutligen jämfördes avvikande geopotentiella höjdmönster i samband med extrema snöfall med tidigare studieresultat av extrem snöackumulation i isborrkärnor från den intilliggande glaciären Eclipse. Resultaten indikerar att dessa mönster delvis korrelerade till tidigare resultat och bekräftar förekomsten av en liknande dipol-tryckstruktur mellan västra Nordamerika och Aleuterna.

This study investigates the impact of the synoptic-scale flow on the propagation and intensity of the sea breeze front at Eglin Air Force Base. The 925 mb wind direction and speed from the 12 UTC Tallahassee sounding was used to categorize 509 summer days as having an offshore, onshore, or coast parallel synoptic-scale flow regimes. Days with similar synoptic-scale flows were then composited together to create hourly surface analyses for each regime. Sea breeze frontogenesis, location and intensity were analyzed on hourly plots of temperature, winds and frontogenesis. Results indicate that the most intense sea breeze fronts formed under 3-5 1 ms- offshore, 7-9 1 ms- coast parallel easterly, and 3-5 1 ms- coast parallel westerly synoptic-scale flow while the weakest fronts formed under 0-3 1 ms- onshore and coast parallel westerly flow. The inland penetration of the sea breeze front was restricted under offshore flow but propagated through the Eglin Range Complex under onshore flow. The intensity of the sea breeze front was found to be a balance between convergence (frontogenetic) and turbulent mixing (frontolytic). Under onshore flow the sea breeze front formed late in the afternoon when convergence at the front was maximized and turbulent mixing decreased. Under offshore flow, the strongest sea breeze fronts formed early in the afternoon due to strong convergence between offshore and onshore winds and weak turbulent mixing.

This thesis seeks to identify locations in which errors in numerical model initial conditions may compromise skill in tropical cyclone (TC) track forecasts. Two major TCs that made landfall in 2008 are analyzed: Hurricane Ike and Typhoon Sinlaku. In order to examine the sensitivity of the TC to selected synoptic features, a vorticity perturbation technique is developed. Within a chosen radius and atmospheric depth, the vorticity is amplified or decreased, followed by a re-balancing of the fields. The following questions are proposed: (1) How does the TC track vary with respect to initial perturbations of differing amplitude, spatial scale and distance to the storm? (2) How does the evolving perturbation act to modify the synoptic environment surrounding the TC, and thereby the track? (3) Is it best to follow an objective technique to determine the sensitive areas, or is it better to use a subjective method based on fundamental synoptic reasoning? Utilizing the Weather Research and Forecasting (WRF) model, the ?control? simulation for each TC is found to replicate forecast errors evident in the operational global models. For Sinlaku, this includes a premature recurvature in the forecast. For Ike, this comprises a landfall too far south along the Texas coast due to no recurvature being forecast. The size, magnitude and location of vorticity perturbations to the control analysis are chosen subjectively. For Sinlaku, these locations include a large mid-latitude shortwave trough around 3000 km to the north-northwest, a smaller upper-level shortwave immediately to the north, a low-level monsoon trough to the west-southwest, a weak tropical storm to the northeast, and a local perturbation in the immediate environment. It is found that WRF forecasts of Sinlaku exhibit high sensitivity, with large modifications to its track arising from the perturbation of each selected targets in the synoptic environment. The greatest improvement in the track forecast occurs by weakening the vorticity associated with each of two shortwaves to the north of Sinlaku, suggesting that either or both of the shortwaves may have been initialized too strongly in the model analysis, thereby contributing to an erroneous recurvature. For Ike, the perturbation locations include a large mid-latitude shortwave trough 2500 km to its north, an upper-level cutoff low to the east-northeast, a low-level shortwave trough to the northwest, a tropical storm in the East Pacific, and a local perturbation in the immediate environment. In contrast to Sinlaku, the perturbation of synoptic targets around Ike produces less sensitivity, likely due to the fact that Ike is not in a position of imminent recurvature. The only perturbation that leads to an accurate 4-day forecast of recurvature and landfall in North Texas is the strengthening of the large mid-latitude shortwave trough, suggesting that the shortwave may have been initialized too weakly in the operational models. Finally, a comparison of targets selected objectively by the Ensemble Transform Kalman Filter (ETKF) versus the above subjectively-chosen targets suggests that while the ETKF effectively indicates similar target regions to those selected subjectively, it may be less effective in ranking the relative sensitivities of those targets. Overall, it is found that the TC track is more sensitive to perturbations of larger amplitude and spatial scale, and less so to the distance between the perturbation and the TC, and sensitivity is confined to specific regions of the flow. The perturbation methodology employed here may be used to offer suggestions of locations in which extra high-density satellite data may be assimilated.

Thesis (S.T.M.)--Concordia Theological Seminary, Ft. Wayne, 1988. / Includes bibliographical references (leaves 124-130).

No description available.