The purpose of the project has been to investigate how synoptic scale climate systems control the frequency of air pollution episodes in the city of Christchurch, New Zealand. The work has been done at the University of Canterbury, New Zealand, and data from the region has been analysed. Air pollution is, during winter time, a growing problem in Christchurch and the project was initiated by the regional environmental legislative body. The first part of the report is on finding relationships on a local-scale between particulate matter concentrations, ground temperature, temperature at 10 meters and wind speed. The data set used in the analysis comes from a monitoring station in St. Albans, situated in the north-east of Christchurch. In the second part, a connection is made thought correlation calculations between the results from the local-scale analysis and the synoptic situation observed over New Zealand during the same period. Two different data sets have been used in the analysis. One data set includes different weather patterns observed over New Zealand and the other data set includes different zonal and meridional circulation indices. A pressure index is also used, the Southern Oscillation Index. On the local-scale, a relationship has been found between the particulate matter concentration and the number of night hours with an inversion present. A correlation also exists between the wind speed and the number of night hours with an inversion present. The connection to the synoptic scale through cluster frequencies and circulation indices was found to be divergent. The cluster frequency analysis indicates on a direct correlation between the Southern Oscillation Index and the air pollution concentration in Christchurch, while the circulation indices analysis indicates on an inverse relationship between the Southern Oscillation Index and the air pollution concentration in Christchurch. / Sammanfattning av ”Kopplingen mellan ENSO och aerosoler mindre än 10 μm i Christchurch” Avsikten med projektet har varit att undersöka om det finns ett samband mellan storskaliga vädersystem (synoptisk skala) och antalet lokalt inträffade händelser med höga halter av luftföroreningar. Arbetet har utförts vid University of Canterbury i Christchurch på Nya Zeeland och mätdata för denna region har analyserats. Luftföroreningar är här ett växande problem, speciellt vintertid, vilket de regionala lagstiftande myndigheterna har identifierat och önskat få utrett. I första delen av rapporten analyseras samband mellan lokala parametrar, så som temperatur vid marknivå och på 10 meters höjd, vindhastighet och koncentrationen av olika luftföroreningar. Data som använts i dessa analyser har uppmätts vid en mätstation placerad i St. Albans, vilken ligger i nordöstra delen av centrala Christchurch. I den andra delen av rapporten beräknas korrelationen mellan resultaten från den lokala analysen och olika synoptiska vädersituationer observerade över Nya Zeeland under motsvarande tidsperioder. Två databaser har använts vid analysen, dels en databas innehållande olika vädersituationer över Nya Zeeland och dels en innehållande olika cirkulationsindex. Dessutom användes också ett lufttrycksindex, ”The Southern Oscillation Index”. Två korrelationer har beräknats i den lokala analysdelen. Dels har ett samband mellan luftföroreningskoncentrationen och antalet timmar med en inversion närvarande nattetid beräknats samt en korrelation mellan vindhastighet och antalet timmar med en inversion närvarande nattetid. Kopplingen till den synoptiska skalan visar på två divergerande resultat. Analys genomförd med olika ”clusters” visar på ett direkt samband mellan ”The Southern Oscillaion Index” och luftföroreningskoncentrationen i Christchurch medan en analys genomförd för circulationsindex visar på ett omvänt samband mellan ”The Southern Oscillation Index” och luftföroreningskoncentrationen i Christchurch.

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 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

Mariepskop (direct translation: “Marieps hill”) forms part of the northernmost edge of the Drakensberg Mountain range in the east of South Africa, and is known for its complex topography associated with meso-scale atmospheric circulation, and therefore its numerous climatic zones. As a result the mountain hosts a high degree of biodiversity. The peak of Mariepskop lies at approximately 1900m Above Mean Sea Level (AMSL), which is higher than the surrounding escarpment to the east bordering the Highveld. Its foothills also extend well into the Lowveld at about 700m AMSL. Mariepskop is therefore ideal for studying airflow exchange between the industrialized Highveld and the Lowveld with its diversity of natural resources. It is also ideal for detecting global warming signals on altitudinal gradients extending from the Lowveld to altitudes above the Highveld escarpment. In this study, long-term National Centre for Atmospheric Research / National Centre for Environmental Prediction (NCAR/NCEP) reanalysis wind data at two atmospheric pressure levels (850hPa and 700hPa), as well as reanalysis near-surface temperature data, were obtained for the Mariepskop region for the austral summer (and winter) seasons. The data was used to force a Computational Fluid Dynamics (CFD) model (also known as STAR-CCM+) across its lateral boundaries with the dominant synoptic flow in order to generate mesoscale simulation output over the complex terrain of Mariepskop. Wind speed and direction modelled results were then correlated to observations measured by three weather stations on Mariepskop. Modelled wind flow results for the summer simulation were also validated against aerial photographs in order to infer whether the model could accurately capture areas with high rainfall, which are related to denser vegetation. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Geography, Geoinformatics and Meteorology / unrestricted

Approved for public release, distribution is unlimited / The Monterey Bay sea breeze varies because of the influence of features such as inversions, clouds, synopticscale flow, and topography. The sea breeze is important because it impacts fire weather, air pollution, agriculture, and aviation operations, among other things. Analyses are conducted using a multi-quadric based program, which incorporates aircraft data, surface observations, and profiler data, to investigate the Monterey Bay sea breeze during 01-31 August 2003. Factors including inversions, cloud cover, amount of heating, distribution of heating, synoptic-scale flow, and topography are studied to determine their influence on the sea breeze. Six days are selected that best illustrate the factors that influence the structure of the Monterey Bay sea breeze. Results show that offs hore flow weakened the strength of the sea breeze and decreased the depth. A cooling trend in surface temperatures at the end of August also weakened the strength of the sea breezes and decreased the depth. Clouds are present during this period, which influenced the amount of heating, and consequently, the sea breeze response. The presence of a marine layer weakened the thermal gradient that in turn, weakened the sea breeze circulation. / Lieutenant Junior Grade, United States Naval Reserve