An examination of the dynamical behavior of H + HD and D + H\u2082 in the ground electronic state is performed on the BKMP2 potential energy surface using the quasiclassical trajectory method. The complete set of state-to-state energy transfer and state-specific dissociative cross sections and thermal rate coefficients has been obtained for both systems. Comparisons are made to the H + H\u2082 system to investigate isotopic effects on reactivity and energy transfer. Collision-induced dissociation, exchange reactions, and non-reactive energy transfer are analyzed and compared to previous results on this system, when such are available. As a prototypical three-body system, H + H\u2082 and its isotopic analogues are interesting as benchmarks for both theoretical and experimental methods. The results of this work can be applied to the general field of molecular reaction dynamics, to interstellar physics and chemistry, to models of planetary atmospheres and stellar system formation, and to studies of the effects of isotopes on reaction rates. The work is motivated by astrophysical applications: in particular, the data may be used as inputs for master equation calculations for interstellar gases.
My dissertation investigates glacier mass change in the Columbia and Rocky Mountains of British Columbia. In chapter one I discuss the importance of the cryosphere and glaciers, introduce the climate and glaciers of the study region, and outline the objectives and structure of this dissertation. Previous work established the feasibility of geodetic methods to accurately produce winter glacier mass balance and annual glacier mass balance. These studies demonstrate that geodetic surveys can be used to estimate mass balance during the accumulation season or for one glacier over a number of years. In chapter two, I refine these published methods to measure seasonal and annual mass balance for six glaciers within two mountain ranges from 2014–2018. I use synchronous field-based glaciological measurements, airbornelaser scanningsurveys (ALS) and satelliteimagery to quantify seasonal glacier mass change from 2014–2018. Chapter three reports on radar surveys I completed of the study glaciers, adding important observations to the global database of ice thickness. I use these observations and an existing flowline model, driven with observations of surface mass balance and glacier elevation to bias-correct ice thickness estimates for each glacier. Finally, I use the model to estimate ice thickness for all glaciers in the Columbia Basin and estimate total ice volume. Chapter four builds upon previous work which used surface topography, glacier mass balance, ice thickness, and ice velocity data to estimate ice flux at discrete glacier cross-sections. Previous efforts to infer the spatial distribution of mass balance have focused on glacier tongues. I expand upon this method, calculating surface mass balance between flux gates over the entire elevation range of three glaciers, over three years. I derive the altitude-mass balance relation and demonstrate that the relation can be accurately described with high-resolution elevation and ice flux data, and suggest that this method can be expanded for large-scale estimates. Chapter five summarizes the study’s major findings, highlights its limitations and discussed its broader implications. Finally, I make recommendations that will address knowledge gaps, and improve our understanding of changing glacier conditions and ability to model glacier dynamics.
Intermontane lakes are often enclosed by complex topography that creates difficulty in resolving the local and regional wind fields. Quesnel Lake, nestled into the western flank of the Cariboo Mountains in central British Columbia, is one such lake. This study examines the wind climatology of Quesnel Lake at three distinct spatial and temporal scales. Firstly, long-term wind data from meteorological stations bordering the Cariboo Mountains exhibit a cycle of calm and active periods throughout the year. Secondly, an environmentto- circulation synoptic climatology is presented that illustrates the large-scale atmospheric patterns that lead to strong wind events at the lake. Finally, the spatial and temporal variability of the near-surface wind field has been examined using an array of shore-based meteorological stations. The response of the wind field to synoptic forcing is found to be driven primarily by the orientation of the regional 800 hPa pressure gradient. iii
Westerly wind bursts (WWBs), usually occurring in the tropical Pacific region, play a vital role in El Niño–Southern Oscillation (ENSO). In this study, we use a hybrid coupled model (HCM) for the tropical Pacific Ocean-atmosphere system to investigate WWBs impact on ENSO. To achieve this goal, two experiments are performed: (a) first, the standard version of the HCM is integrated for years without prescribed WWBs events; and (b) second, the WWBs are added into the HCM (HCM-WWBs). Results show that HCM-WWBs can generate not only more realistic climatology of sea surface temperature (SST) in both spatial structure and temporal amplitudes, but also better ENSO features, than the HCM. In particular, the HCM-WWBs can capture the central Pacific (CP) ENSO events, which is absent in original HCM. Furthermore, the possible physical mechanisms responsible for these improvements by WWBs are discussed.
Air pollution has been an ongoing issue for the City of Prince George, the largest city in northern British Columbia. This research was designed to measure the chemical composition of atmospheric Particulate Matter (PM2.5) in a Prince George neighborhood (i.e., downtown). The main objective of this research was to determine the PM2.5 chemical compositions in two distinct periods: warm and cold. Overall, 153 samples were collected from January to August 2018, using personal air samplers. The highest concentration of PM2.5 was recorded during the 2018 summer wildfires. Chemical composition of the PM2.5 air samples were studied with respect to Cadmium, Potassium, Mercury, Sodium, Lead, Chromium, Iron, Cobalt, Nickel, Manganese, Copper, Titanium, Molybdenum, Phosphorus and Sulphur, in order to evaluate potential sources of air pollutants in the city. The results of this study were compared with PM2.5 averages from other Canadian and international cities. The possibilities of the contribution of some local industrial sources such as pulp and paper, biomass burning, transportation and road dust, on PM2.5 concentration and chemical composition were discussed.
