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Cosmology with next generation radio telescopesWitzemann, Amadeus January 2019 (has links)
Philosophiae Doctor - PhD / The next generation of radio telescopes will revolutionize cosmology by
providing large three-dimensional surveys of the universe. This work presents
forecasts using the technique 21cm intensity mapping (IM) combined with
results from the cosmic microwave background, or mock data of galaxy
surveys. First, we discuss prospects of constraining curvature independently
of the dark energy (DE) model, finding that the radio instrument HIRAX
will reach percent-level accuracy even when an arbitrary DE equation of state
is assumed. This is followed by a study of the potential of the multi-tracer
technique to surpass the cosmic variance limit, a crucial method to probe
primordial non-Gaussianity and large scale general relativistic e↵ects. Using
full sky simulations for the Square Kilometre Array phase 1 (SKA 1 MID)
and the Large Synoptic Survey Telescope (LSST), including foregrounds, we
demonstrate that the cosmic variance contaminated scenario can be beaten
even in the noise free case. Finally, we derive the signal to noise ratio for the
cosmic magnification signal from foreground HI intensity maps combined
with background galaxy count maps. Instruments like SKA1 MID and
HIRAX are highly complementary and well suited for this measurement.
Thanks to the powerful design of the planned radio instruments, all results
confirm their potential and promise an exciting future for cosmology.
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Improving Short-Range Cloud Forecasts in Harmonie-Arome Through Cloud Initialization Using Mesan Cloud DataPyykkö, Joakim January 2019 (has links)
Previous studies, such as van der Veen (2012) and White et al. (2017), have demonstrated the potential of using measurement-based cloud data to improve Numerical Weather Prediction (NWP) based cloud forecasts. This can be done through cloud initialization; a process of injecting cloud data after the regular data assimilation in an NWP model. The purpose of this study was to use cloud data from the Mesoscale Analysis system MESAN to investigate cloud initialization in the HARMONIE-AROME model system for improving short-range cloud forecasts. The cloud initialization method that was used was similar to a method used by van der Veen (2012), where specific humidities, temperatures, and hydrometeor concentrations were altered using information on cloud fractions, cloud base heights and cloud top heights. MESAN input data analyses as well as cloud initialization investigations were carried out. MESAN input data analyses revealed significant differences in cloud fractions between MESAN and the background model field in MESAN. Overestimations of cloud fractions in MESAN over sea were caused by satellite data, particularly due to the inclusion of the fractional cloud category. Underestimations of cloud fractions over land were caused by limitations of the synoptic weather (SYNOP) stations in measuring clouds. Furthermore, larger differences between MESAN and SYNOP were found over Sweden and Finland compared to Norway, which may be tied to Norway having mostly manual SYNOP stations, and Sweden and Finland having mostly automatic stations. Shortcomings were found in the investigated cloud initialization method. Such shortcomings involved a limit check on the specific humidity change, the cloud initialization being repeated for an unnecessarily large amount of iterations, and the use of a sub-optimal profile of critical relative humidity. Using a one-dimensional vertical column version of HARMONIE-AROME, named MUSC, to integrate forward in time revealed a large sensitivity to the use of forcing profiles and forcing time scales in MUSC. Alterations made through cloud initialization were found to last over 12 h, with varying effects depending on the investigated height. A reasonably good agreement between MUSC results and results from the three-dimensional version of HARMONIE-AROME was found. Findings in this thesis point at potential to further enhance the HARMONIE-AROME cloud initialization technique. These enhancements concern a revised MESAN cloud product and taking care of some flaws in the cloud initialization method. / I en operationell vädermodell inkluderas olika mätdata, såsom temperatur och atmosfärstryck, i ett regelbundet intervall. Molnighet är inte vanligtvis en del av dessa cykler; istället bildas molnen av modellen utifrån balanser i de andra fysikaliska fälten. Detta projekt gick ut på att direkt införa molnmätningar från väderanalyssystemet MESAN i vädermodellsystemet HARMONIE-AROME genom en metod som kallas molninitialisering. Specifikt förbättringar för korttidsprognoser var av i ntresse. MESAN är ett system vars produkter är en sammanslagning av ett bakgrundsfält från en vädermodellkörning med olika mätdata. I MESAN kommer molndata från tre källor: bakgrundsfältet, satellitdata och synoptisk väderstationsdata (SYNOP-data). Undersökningar av indata till MESAN samt molninitialiseringsmetoden har utförts. Analyser av indata till MESAN visade på överskattningar av moln i satellitdata över hav och underskattningar av moln i SYNOP-data över land. För satellitdatat berodde detta på medtagande av moln på liten skala eller väldigt tunna moln, medan det för SYNOP berodde på begränsningar i mätmetoderna. Det fanns även en skillnad i kvalitet i SYNOP-data i Sverige och Finland gentemot Norge, vilket kan bero på att de flesta mätstationer i Norge är manuella medan de flesta i Sverige och Finland är automatiska. Molninitialiseringsmetoden bestod i att extrahera data om molnbashöjd och molntopphöjd från MESAN, och sedan modifiera fuktighet, temperatur och hydrometeorer (såsom molndroppar och iskristaller) i HARMONIE-AROME utifrån molnens position. Brister i metoden hittades. Initialiseringsprocessen upprepades ett suboptimalt antal gånger. En begränsning i hur mycket fuktigheten tillåts modifieras förändras under initialiseringsprocessen och fungerade inte som avsett. Dessutom, jämförese med radiosonddata pekar på att relativa fuktighetsgränserna för villket moln bildas inledningsvis inte ansattes korrekt. Effekterna av metoden kunde vara i över 12 timmar, men denna studie pekar på ytterligare troliga förbättringsmöjligheter i HARMONIE-AROME genom införande av reviderad version av metoden samt förbättrade satellitprodukter.
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Snowfall event analysis at a remote northern alpine icefieldCourtin, Eric 31 May 2018 (has links)
Data are presented from an automatic weather station on the Brintnell-Bologna Icefield that operated from August 2014 to August 2016 in Nahanni National Park Reserve. This location is notable for being the northernmost mass balance alpine study location of the federal government’s glaciology program (NRCan/GSC). The link between atmospheric forcing at the synoptic scale and response at the glacier surface has been shown to be strongly dependent on continentality and latitude. In this region, however, many aspects of the physical processes controlling the interaction between atmospheric forcing and snowpack response are virtually unknown, especially at the daily to hourly timescale.
The character of snowfalls during the accumulation seasons for this icefield are investigated using high resolution time series from two acoustic snow depth sensors and other relevant meteorological parameters. It is found that the most drastic changes in snow depth occur from infrequent large snowfalls. Using an adaption of an Environment Canada snow depth algorithm, snowfall events are identified and their timing is quantified based on a system of thresholds, running averages and ratios between the snow depth sensors. Synoptic conditions are examined using meteorological reanalysis data and trajectory analysis to determine the moisture origin and pathway. / Graduate
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The Weather of 1785: An Interdisciplinary Approach to Meteorological Reconstruction Using Forensic Synoptic AnalysisMcNally, Louis K. January 2004 (has links) (PDF)
No description available.
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The Influence of Synoptic Weather Conditions on Weekday-weekend Effect of Extreme Ground-level Ozone Events in the Toronto areaLeung, Kinson He Yin 10 January 2011 (has links)
Ground-level ozone (O3) is a familiar pollutant because it is associated with summer haze and smog alerts. The 2000-2008 weekday-weekend variations of ozone concentration were examined in relation to the Toronto weather conditions. The goal of this work is twofold: (1) To determine whether extreme ozone events were associated with specific weather conditions, (2) To determine whether the weekday-weekend effect of extreme ozone events could be detectable during the nine-year study period. The results show that in the study period, there were totally 313 days having extreme ground-level ozone events with ozone concentration ≥ 80 ppb, which is the current Ontario Ambient Air Quality Criterion for ozone concentration, in the four selected Toronto sites. Additionally, the weather condition mainly associated with these 313 days was the Dry Tropical one. This study also shows the phenomenon of the weekday-weekend effect of extreme ozone events in the past nine years in Toronto.
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The Influence of Synoptic Weather Conditions on Weekday-weekend Effect of Extreme Ground-level Ozone Events in the Toronto areaLeung, Kinson He Yin 10 January 2011 (has links)
Ground-level ozone (O3) is a familiar pollutant because it is associated with summer haze and smog alerts. The 2000-2008 weekday-weekend variations of ozone concentration were examined in relation to the Toronto weather conditions. The goal of this work is twofold: (1) To determine whether extreme ozone events were associated with specific weather conditions, (2) To determine whether the weekday-weekend effect of extreme ozone events could be detectable during the nine-year study period. The results show that in the study period, there were totally 313 days having extreme ground-level ozone events with ozone concentration ≥ 80 ppb, which is the current Ontario Ambient Air Quality Criterion for ozone concentration, in the four selected Toronto sites. Additionally, the weather condition mainly associated with these 313 days was the Dry Tropical one. This study also shows the phenomenon of the weekday-weekend effect of extreme ozone events in the past nine years in Toronto.
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The Significance of Jesus' Healing Miracles: A Study of their Role in the Synoptic Gospels and their Importance to Early ChristianityCadenhead, John Morgan 20 November 2008 (has links)
This essay examines the healing miracles of Jesus as described by the Synoptic Gospels and posits that the appeal of the Synoptics over non-canonical texts can partially be found in the former’s focus on these physical healing miracles. The essay argues that the idea that one can be healed of physical pain through faith is a varied theme in the Synoptics and a strong motivator to bring an interest in early Christianity, especially during a time of persecution. Further, this essay considers Gnostic Gospels and their relative lack of healing miracles to expand upon a theory put forth by Elaine Pagels, namely that the early church declared Gnostic texts to be heretical in part because they did not cater to the basic needs of the people as the Synoptics did.
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Halakic (legal) controversies between Bet Hillel, Bet Shammai and JesusBradford, Johnnie Edgar 18 June 2015 (has links)
The synoptic gospels of Matthew, Mark and Luke are commonly regarded as biographical in nature in their presentation of the life and teachings of Jesus. The gospels of Matthew and Luke report that Jesus was born a Hebrew among Hebrews, raised as a Jew within the Jewish nation, and functioned a first century Rabbi in a completely Jewish context during which time he started his own movement called the kingdom of heaven. The Rabbis of that day commonly enlisted a group of followers or disciples. The combination of a Rabbi and his students constituted an academy. Two schools or academies existed during the time of Jesus and were contemporary with him, the school of Shammai and the school of Hillel. The Babylonian Talmud dating from 500 C.E. records exactly three hundred and sixteen legal controversies between these two schools. Legal disputes between Jesus and representatives of one or the other existing schools of thought are recorded in the synoptic gospels. Each record clearly identifies the subject under dispute and the positions of the disputing parties. Nevertheless, the incomplete information provided in the synoptic gospels is not sufficient to allow readers to understand the dispute at hand. For example, a group of unidentified Pharisees approach Jesus with a specific question regarding the legalities of divorce. They ask the following question: "Is it lawful to divorce one's wife for any cause (Matthew 19:3)?" This question can raise these questions in the readers minds: Why was this question presented to Jesus? What is the background of this legality? What is the actual law regarding this matter? Is this an unresolved issue? Who are the parties involved in resolving this issue? Is there more detailed information regarding this issue? Ancient Jewish sources provide answers to all of these questions. This dissertation provides the material lacking in the synoptic gospels to enable one to understand the controversy and Jesus' interpretation. This will be accomplished through use of Jewish sources that provide the details of the disputes recorded in the synoptic gospels as well as identifying the various parties involved. Behind the process of presenting background information in this dissertation lies the premise that any study of the life and teachings of Jesus performed without consulting ancient Jewish sources will result in confusion and misunderstanding. This dissertation highlights information relating to these controversies that is lacking in the synoptic gospels and will enable the reader to understand the nature of the controversy and Jesus' conclusions. / text
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Impact of Climate Change on Fine Particulate Matter \((PM_{2.5})\) Air QualityTai, Pui Kuen Amos P. K. 19 March 2013 (has links)
This dissertation investigates the impact of 2000-2050 climate change on fine particulate matter \((PM_{2.5})\) air quality. We first applied a multiple linear regression model to study the correlations of total \(PM_{2.5}\) and its components with meteorological variables using the past decadal \(PM_{2.5}\) observations over the contiguous US. We find that daily variation in meteorology can explain up to 50% of \(PM_{2.5}\) variability. Temperature is positively correlated with sulfate and organic carbon (OC) almost everywhere. The correlation of nitrate with temperature is negative in the Southeast but positive in California and the Great Plains. Relative humidity (RH) is positively correlated with sulfate and nitrate, but negatively with OC. Precipitation is strongly negatively correlated with all \(PM_{2.5}\) components. We then compared the observed correlations of \(PM_{2.5}\) with meteorological variables with results from the GEOS-Chem chemical transport model. The results indicate that most of the correlations of \(PM_{2.5}\) with temperature and RH do not arise from direct dependence but from covariation with synoptic transport. We applied principal component analysis and regression to identify the dominant meteorological modes controlling \(PM_{2.5}\) variability, and showed that 20-40% of the observed \(PM_{2.5}\) daily variability can be explained by a single dominant meteorological mode: cold frontal passages in the eastern US and maritime inflow in the West. From 1999-2010 observations we further showed that interannual variability of annual mean \(PM_{2.5}\) in most of the US is strongly correlated with the synoptic period T of the dominant meteorological mode as diagnosed from a spectral-autoregressive analysis. We then used the observed local \(PM_{2.5}\)-to-period sensitivity to project \(PM_{2.5}\) changes from the 2000-2050 changes in T simulated by fifteen IPCC AR4 GCMs following the SRES A1B scenario. We project a likely increase of \(\sim 0.1 \mu g m^{-3}\) in annual mean \(PM_{2.5}\) in the eastern US arising from less frequent frontal ventilation, and a likely decrease of \(\sim 0.3 \mu g m^{-3}\) in the northwestern US due to more frequent maritime inflows. These circulation-driven changes are relatively small, representing only a minor climate penalty or benefit for \(PM_{2.5}\) regulatory purpose. / Engineering and Applied Sciences
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From sex tapes to revenge porn: Construction of a genre : Gender, sexuality and power in new mediaMd, Nabil January 2012 (has links)
This paper makes an attempt to explain the construction of a newly developed genre called revenge porn flourishing in new media. The study analyzes the patterns of production and display of revenge porn content as well as the mechanisms of the site that archives such materials. The results of this study suggest that the development of such a genre cannot be attributed only to liberatory and/or victimizing effects of the electronic space. Rather, social power structures based on discourses like gender, heterosexuality and capitalist patriarchy that exploit the surveillance mechanism of the internet are significantly influencing both individual uses of the internet as well as its apparatus and technologies. These are the major forces contributing to the institutionalization and commercialization of revenge porn in new media. This is a case study based investigation that uses both content analysis and discourse analysis as methods to interpret the revenge porn genre in new media.
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