Physical Sciences and Mathematics Commons^™

Effect Of Morphology And An Upstream Tall Building On A Street Canyon Flow, Haoran Du

Electronic Thesis and Dissertation Repository

The effects of the morphological model and the existence of an upstream tall building on the turbulent street canyon flow and the overlying boundary layer are investigated in a wind tunnel, using Stereoscopic Particle Image Velocimetry (S-PIV) measurements. The velocity variances, Reynolds shear stress, and turbulent kinetic energy are found to be larger than in a similar idealized street canyon model. Increasing building height results in a decrease in vertical mass fluxes across the opening of the canyon, at least in the canyon portion directly downstream of the building. The interaction between the large-scale structures in the overlying boundary layer …

Stable Carbon And Oxygen Isotopes Of Early Silurian Pentameride Brachiopods From Québec, Ontario, And Nunavut, And Paleoenvironmental Implications, Jordan N. Siewnarine

Electronic Thesis and Dissertation Repository

Analysis of low-Mg calcite brachiopod shells for δ¹⁸O and δ¹³C signatures provide quantitative independent geochemical data for paleoenvironmental interpretations. We analyzed 59 brachiopod shells from lower Silurian carbonate rocks of Anticosti Island, the Hudson Bay Lowlands and Niagara regions for spaciotemporal isotopic trends for the early Silurian. Screening tests using scanning electron microscopy, cathodoluminescence and trace element analysis demonstrate exceptional preservation, suggesting retention of primary isotopic values.

δ¹³C and δ¹⁸O values of shells range from 0.2‰ to 2.9‰ and -6.9‰ to -4.3‰ (VPDB), respectively. Temporally, increases in δ¹³C and δ …

Physical Investigation Of Downburst Winds And Applicability To Full Scale Events, Federico Canepa

Electronic Thesis and Dissertation Repository

Thunderstorm winds, i.e. downbursts, are cold descending currents originating from cumulonimbus clouds which, upon the impingement on the ground, spread radially with high intensities. The downdraft phase of the storm and the subsequent radial outflow that is formed can cause major issues for aviation and immense damages to ground-mounted structures. Thunderstorm winds present characteristics completely different from the stationary Gaussian synoptic winds, which largely affect the mid-latitude areas of the globe in the form of extra-tropical cyclones. Downbursts are very localized winds in both space and time. It follows that their statistical investigation, by means of classical full scale anemometric …

Building Climate Resilient Communities: Living Within The Earth’S Carrying Capacity, Gordon Mcbean, Paul Kovacs, James Voogt, Greg Kopp, Sophie Guilbault

Geography & Environment Publications

This Knowledge Synthesis examines how Canadian communities can proactively advance climate resilience to effectively reduce the risk from climate change impacts.

Our synthesis reveals that some communities have prepared high level adaptation plans, but very few have a detailed implementation strategy with established funding frameworks. Most actions to build community resilience in Canada are unplanned and take place in recovery following an extreme loss event. Indigenous communities are at the forefront of climate change adaptation in Canada. Self-determination and adaptive capacity building through community-led risk assessments, planning, and disaster recovery organizations, while addressing the broader context of reconciliation gaps and …

Studies Of The Tilts Of Atmospheric Scatterers By Windprofiler Radars, Farnoush Attarzadeh

Electronic Thesis and Dissertation Repository

MST (Mesosphere–Stratosphere–Troposphere) radars are powerful instruments for observing the differences in refractive indexes in the air. By tracking refractive index perturbations, these radars can determine wind speeds and turbulence strengths in the atmosphere from the ground up to 15 km altitude. In this project, we used 6 Doppler Radars to study the correlation between horizontal and vertical winds in the Troposphere to find scatterer tilts. However, instrumental effects due to small tilts in the radar beam can also cause such correlations, thus our studies cover that as well. Scatterers are best known for being the result of turbulence and waves …

Raman-Scatter Lidar Measurements Of Water Vapor Determined Using An Integrated Microwave Radiometer-Lidar Retrieval, Jeffrey Vankerkhove

Electronic Thesis and Dissertation Repository

Water vapor plays a crucially important role in many atmospheric processes. However, it is poorly characterized in much of the atmosphere. Vibrational Raman-scattering Lidar has excellent spatial and temporal resolution, but requires an external calibration to correct for instrumental biases. Microwave Radiometers have poorer resolution, but can be calibrated absolutely and can be used to calibrate the Lidar system. I have implemented a new technique, incorporating both instruments to generate a calibrated water vapor mixing ratio profile. This integrated retrieval uses an inverse method which includes a combined forward model, integrating radiative transfer equations (Schroeder and Westwater 1991) and lidar …

Comparative Assessment Of Downscaling Methods And Application Towards Analysis Of Climate Change Impact On Urban Regions, Markus Eichenbaum

Electronic Thesis and Dissertation Repository

Global climate models (GCM) are sophisticated numerical models used to make long term climate projections. However, the resolution of their output is too coarse for climate change related local impact studies on urban regional scales. Downscaling efforts are taken to address this and increase GCM projection resolution. Physical Scaling (SP) downscaling methodology attempts to incorporate the physical basis of dynamical downscaling efforts with the computational efficiency of statistical methods. In this study, North American Regional Reanalysis surface skin temperature and precipitation data for a 1°x1° region centered on Houston, TX are downscaled to a resolution of 500m via SP and …

The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a collective prediction among ecologists that climate change will enhance phytoplankton biomass in temperate lakes. Yet there is noteworthy variation in the structure and regulating functions of lakes to make this statement challengeable and, perhaps, inaccurate. To generate a common understanding on the trophic transition of lakes, I examined the interactive effects of climate change and landscape properties on phytoplankton biomass in 12,644 lakes located in relatively intact forested landscapes. Chlorophyll-a (Chl-a) concentration was used as a proxy for phytoplankton biomass. Chl-a concentration was obtained via analyzing Landsat satellite imagery data over a 28-year period (1984-2011) and using …

A Tropospheric Water Vapour Climatology And Trends Derived From Vibrational Raman Lidar Measurements Over Switzerland, Shannon Hicks-Jalali

Electronic Thesis and Dissertation Repository

Water vapour is the most effective atmospheric greenhouse gas in terms of warming the atmosphere. Water vapour can magnify the temperature increase that CO₂ would cause alone by 2-3 times. As such, it is critical to monitor changes in water vapour abundance to better understand its role in atmospheric change. I have used 10 years of lidar and radiosonde measurements from the MeteoSwiss research station in Payerne, Switzerland to calibrate the lidar, improve its water vapour retrievals, and finally calculate a lidar water vapour climatology and trend analysis.

Calculating trends with a lidar requires rigorous calibration. Therefore, my first …

Development Of A 1-Dimensional Data Assimilation To Determine Temperature And Relative Humidity Combining Raman Lidar Backscatter Measurements And A Reanalysis Model, Shayamila N. Mahagammulla Gamage

Electronic Thesis and Dissertation Repository

Water vapor is the most dominant greenhouse gas in Earth's atmosphere. It is highly variable and its variations strongly depend on changes in temperature. Atmospheric water vapor can be expressed as relative humidity (RH), the ratio of the partial pressure of water vapor in the mixture to the equilibrium vapor pressure of water over a flat surface of pure water at a given temperature. Liquid water can exist as super-cooled water for temperatures between 0C to -38C. Thus, RH can be measured either relative to water (RHw) or to ice (RHi). RHi measurements are important in the upper tropospheric region, …

Application Of The Optimal Estimation Method (Oem) To Retrieve Relative Humidity From Raman Lidar Backscatter Measurements., Shayamila N. Mahagammulla Gamage, Robert Sica, Alexander Haefele

Western Research Forum

Accurate measurements of relative humidity (RH) vertical profiles in the atmosphere is important for understanding the earth's weather and the climate system. RH represent the current state of the water vapor in the atmosphere with respect to the ambient air related to saturation. Even minor changes of the RH in the lower atmosphere has a large impact of the global circulation and cloud formation. Due to its high variability RH measurements in the lower atmosphere is significantly challenging. Raman lidar is one of the potential tools that can provide vertical profiles of RH. Typically, temperature and water vapor mixing ratios …

Integrated Raman Lidar And Microwave Radiometer Retrieval Of Atmospheric Water Vapor, Jeffrey Vankerkhove, Robert Sica, Alexander Haefele

Western Research Forum

Water vapor plays a critically important role in many atmospheric processes. However, it is poorly characterized throughout much of the atmosphere, particularly in the UTLS (Upper Troposphere Lower Stratosphere) region, due to lack of accurate measurements. Raman lidar boasts the capacity for excellent spatial and temporal resolution, but requires an external calibration. Microwave radiometers can be calibrated in absolute terms, but have poor height resolution. In this study, we introduce an integrated water vapor retrieval using an optimal estimation method, where the measurements from the Raman Lidar for Meteorological Observation (RALMO) and a RPG-HATPRO radiometer, both located at the MeteoSwiss …

Validating And Highlighting The Advantages Of The Optimal Estimation Method For Rayleigh Lidar Middle Atmospheric Temperature Retrievals, Ali Jalali

Electronic Thesis and Dissertation Repository

An improved understanding of temperature variations in Earth’s middle atmosphere is important for the improvement of our understanding of climate and weather on the surface. The optimal estimation method (OEM) is an inversion modeling approach, which uses regularized nonlinear regression to retrieve, in this case, the temperature of Earth’s middle atmosphere using Rayleigh-scatter lidar measurements. The OEM regularization term is the a priori knowledge of the atmospheric temperature profile. In this thesis I use lidar temperatures in the altitude range 30–110km to construct a temperature climatology using over 500 nights of measurements obtained by the Purple Crow Lidar in London, …

The Periglacial Landscape Of Mars: Insight Into The 'Decameter-Scale Rimmed Depressions' In Utopia Planitia, Arya Bina

Electronic Thesis and Dissertation Repository

Currently, Mars appears to be in a ‘frozen’ and ‘dry’ state, with the clear majority of the planet’s surface maintaining year-round sub-zero temperatures. However, the discovery of features consistent with landforms found in periglacial environments on Earth, suggests a climate history for Mars that may have involved freeze and thaw cycles. Such landforms include hummocky, polygonised, scalloped, and pitted terrains, as well as ice-rich deposits and gullies, along the mid- to high-latitude bands, typically with no lower than 20o N/S. The detection of near-surface and surface ice via the Phoenix lander, excavation of ice via recent impact cratering activity as …

Microclimate Variability Of Select Toronto Neighbourhoods Under Hot Summertime Conditions, Timothy Wiechers

Electronic Thesis and Dissertation Repository

Micrometeorological variability within cities has important implications for urban air and water quality, building energy consumption, and human health and thermal comfort. However, the monitoring of microscale climate is not routinely conducted. In most instances, primary meteorological observations are made under reproducible standard conditions (typically at an airport); but these open field observations tend to be unrepresentative of the intra-urban meteorological conditions.

This thesis used an alternative approach of conducting mobile traverse measurements using vehicle-mounted sensors to characterize the microclimates of Toronto, ON under hot, summertime weather conditions. Sampling occurred along two routes and incorporated sampling 8 intra-urban neighbourhoods with …

Ceilometer Measurements From The University Of Western Ontario Of Smoke From The Extraordinary Fires Of 2017 In Western Canada, Achini J K Abayakoon Ms.

Western Research Forum

Background:

The summer of 2017 saw many fires in Western Canada. Smoke from these fires was transported by winds over to London and was measured using a Lufft CHM15k ceilometer which was installed at the Cronyn Observatory of The University of Western Ontario.

Methods:

The cloud base height can be calculated by the time taken for the backscatter signal to reach the transmitter while the backscatter effects can be used to determine the atmospheric structure using the principle of light detection and ranging (LiDAR).

Results:

Smoke particle concentrations over London, Ontario were observed within 72 hours of the fires taking …

Using Bolide Airwaves To Estimate Meteoroid Source Characteristics And Window Damage Potential, Nayeob Gi

Electronic Thesis and Dissertation Repository

We examined the far-field infrasonic signals produced by 78 bolides simultaneously detected by U.S. government sensors to determine the mechanisms responsible for interstation spreads in infrasound signal period. These signal period spreads lead to large variances in source energy estimates. Our analysis suggests that while acoustic source height contributes to some extent to the variance in signal periods, the range from the source to the station and in particular station noise plays a more significant role.

By simulating the near-field weak shocks from a suite of well-observed energetic fireballs, we have empirically estimated how often fireball shocks produce overpressure ( …

A Method For Hemispherical Ground Based Remote Sensing Of Urban Surface Temperatures, Michael A. Allen

Electronic Thesis and Dissertation Repository

This thesis presents a method for deriving time-continuous urban surface temperature and heat island assessments from hemispherical ground-based measurements of upwelling thermal radiation. The method, developed to overcome geometric and temporal biases inherent in traditional thermal remote sensing of urban surface climates, uses a sensor view model in conjunction with a radiative transfer code to derive atmospherically corrected, hemispherical radiometric urban surface temperatures. These are used to derive two long-term climatologies of surface urban heat island (sUHI) magnitudes for Basel, Switzerland and Vancouver, Canada. sUHI development shows significant variation based on time-of-day, season, and ambient and synoptic conditions. Results also …

P16. Ralmo Rotational Raman Temperature Retrieval: First Steps Towards The Application Of Optimal Estimation Method (Oem), Shayamila N. Mahagammulla Gamage, Robert Sica, Alexander Haefele

Western Research Forum

Background:

Temperature is an important atmospheric parameter that plays an extensive role in the fields of atmospheric dynamics, climatology, meteorology, and chemistry. Light detection and ranging (lidar), is a remote sensing technology that can be used for atmospheric temperature profiling. A lidar transmits short laser pulses into the atmosphere and the light scattered by the particles in the atmosphere is collected and measured using a telescope. The atmospheric temperatures can be retrieved by analysing the Pure Rotational Raman (PRR) scatter measurements from the nitrogen and oxygen molecules in the atmosphere.

Methods:

In this study use the Optimal Estimation Method (OEM) …

P07. Characterizing The Purple Crow Lidar To Investigate Potential Sources Of Wet Bias, Jeffrey Vankerkhove, Robert J. Sica, Robin Wing, Steve Argall

Western Research Forum

The Purple Crow Lidar is a large aperture lidar, capable of retrieving water vapor profiles into the stratosphere. Water vapor in the upper Troposphere-Lower Stratosphere (UTLS) region is of particular importance in understanding Earth's radiative budget and atmospheric dynamics, making accurate UTLS measurements crucial. A comparison campaign with the NASA/GSFC ALVICE mobile lidar in the spring of 2012 showed PCL water vapor measurements were consistently larger than those of ALVICE in the lower stratosphere, prompting an investigation to characterize the system. The investigation looks into how changes to the data processing approach, as well as applying additional instrumental corrections, would …

Multiscale Wind Modelling For Sustainability And Resilience, Djordje Romanic

Electronic Thesis and Dissertation Repository

The research presented herein is a mix of meteorological and wind engineering disciplines. In many cases, there is a gap between these two fields and this thesis is an attempt to bridge that gap through multiscale wind modelling approaches. Data and methods used in this study cover a multitude of spatial and temporal scales. Applications are in the fields of sustainability and resilience. This relationship between multiscale wind modelling and sustainability and resilience is investigated examining several case studies of three different developments: urban, rural and coastal.

An urban wind modelling methodology is proposed and applied for a specific development …

Agriculture Causes Nitrate Fertilization Of Remote Alpine Lakes, Elizabeth J. Hundey, Sam S.D. Russell, Fred Longstaffe, Katrina A. Moser

Earth Sciences Publications

Humans have altered Earth’s nitrogen cycle so dramatically that reactive nitrogen (Nr) has doubled. This has increased Nr in aquatic ecosystems, which can lead to reduced water quality and ecosystem health. Apportioning sources of Nr to specific ecosystems, however, continues to be challenging, despite this knowledge being critical for mitigation and protection of water resources. Here we use D¹⁷O, d¹⁸O and d¹⁵N from Uinta Mountain (Utah, USA) snow, inflow and lake nitrate in combination with a Bayesian-based stable isotope mixing model, to show that at least 70% of nitrates in aquatic systems are anthropogenic …

A New Technique For Interpreting Depolarization Measurements Using The Crl Atmospheric Lidar In The Canadian High Arctic, Emily M. Mccullough

Electronic Thesis and Dissertation Repository

Linear depolarization measurement capabilities were added to the CANDAC Rayleigh-Mie-Raman lidar (CRL) at Eureka, Nunavut, in the Canadian High Arctic. This upgrade enables inferences of the phases (liquid versus ice) of cold and mixed-phase clouds, including during polar winter. A rotating-polarizer module was installed in the lidar, and depolarization measurements were calibrated according to existing methods. An alternate calculation technique, using the lidar's existing visible Rayleigh elastic channel in combination with the new rotating polarizer channel, was developed. A detailed mathematical description of both methods and their calibrations is presented. The new method is superior to the traditional method for …

Exploration Of Spatial And Temporal Changes In Trophic Status Of Lakes In The Northern Temporal Forest Biome Using Remote Sensing, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a critical need for detailed surveys of lakes covering large spatial (>100 km²) and temporal scales (decades) to determine if there is an increase in the magnitude and frequency of phytoplankton blooms. Remote sensing was used to: (1) develop a regression model that relates chlorophyll a (chl-a) as a proxy of lake phytoplankton biomass to Landsat TM and ETM+ optical reflectance (r²=0.85, p

Perspectivas Culturais Na Comunicação Climática (Cultural Perspectives On Climate Communication), Karen E. Pennesi

Anthropology Publications

Este artigo considera que a previsão climática deve ser interpretada dentro de contextos sociais, culturais e linguísticos. Dentro de uma perspectiva antropológica baseada em entrevistas, observações e um questionário, será investigado como mudanças no meio-ambiente são entendidas por diferentes indivíduos, e transformadas em previsões que são comunicadas a diversos públicos. A linguagem utilizada e a maneira como a previsão é comunicada depende da experiência e dos objetivos do previsor, enquanto que a interpretação e a avaliação da previsão por outros são influenciadas por seus diferentes objetivos, atitudes, conhecimento e práticas. Esta etnografia da comunicação enfatiza o processo da comunicação das …

Automated Image Interpretation For Science Autonomy In Robotic Planetary Exploration, Raymond Francis

Electronic Thesis and Dissertation Repository

Advances in the capabilities of robotic planetary exploration missions have increased the wealth of scientific data they produce, presenting challenges for mission science and operations imposed by the limits of interplanetary radio communications. These data budget pressures can be relieved by increased robotic autonomy, both for onboard operations tasks and for decision- making in response to science data.

This thesis presents new techniques in automated image interpretation for natural scenes of relevance to planetary science and exploration, and elaborates autonomy scenarios under which they could be used to extend the reach and performance of exploration missions on planetary surfaces.

Two …

The Periglacial Landscape Of Utopia Planitia; Geologic Evidence For Recent Climate Change On Mars., Mary C. Kerrigan

Electronic Thesis and Dissertation Repository

The northern plains of Utopia Planitia, Mars, hosts an abundance of potential periglacial landforms including scalloped depressions, gullies, and polygon networks. This research was undertaken to investigate the distribution and stratigraphy of scalloped depressions in Utopia Planitia and to reconstruct the past environment in which this periglacial landscape formed. To that end, a revised geologic map of the region has been produced. We define, for the first time, a new Periglacial Unit, the youngest geologic unit in Utopia Planitia. We have also developed a model for the formation and evolution of the periglacial landscape examined by assessing the use of …

Multi-Sensor Calibration And Validation Of The Uwo-Pcl Water Vapour Lidar, Robin Wing

Electronic Thesis and Dissertation Repository

The Purple Crow Lidar (PCL) has recently participated in a water vapour validation cam- paign with the NASA/GSFC Atmospheric Laboratory for Validation/Interagency Collaboration and Education (ALVICE) Lidar. The purpose of this calibration campaign is to insure that PCL water vapour measurements are of sufficient quality for use in scientific investigations of atmo- spheric change, and to be included in the Network for the Detection of Atmospheric Climate Change (NDACC) data base. The detection of long term changes in water vapour concentra- tion, particularly in the upper troposphere and lower stratosphere (UTLS) is an issue of pressing scientific, ecological and societal …

Diatoms In Castor Lake (North-Central Washington, Usa) – Proxies Of Climate And Hydrologic Variation, Kelly D. Hollingshead

Electronic Thesis and Dissertation Repository

This research provides a high temporal resolution (1 sample / 2-3 years) record of hydrologic variation for the last 2,000 years using a lake sediment record from Castor Lake, a closed-basin system in Washington, USA. The core was dated using ¹³⁷Cs, ¹⁴C, and tephrochronology. Approximately 600 diatoms were identified and enumerated in 198 samples from a Castor Lake freeze core and Livingstone-piston core. A diatom-inference model for salinity was applied to reconstruct fossil diatom salinity. Diatom-inferred salinity for the last century tracked Palmer Drought Severity Index, indicating diatom community composition tracks effective moisture and can be used to …

A Study On The Turbulent Characteristics Within The Hurricane Boundary Layer, Sunwei Li

Electronic Thesis and Dissertation Repository

As the medium between the sea surface and the upper atmosphere in a hurricane, the Hurricane Boundary Layer (HBL) plays a key role in the overall dynamics of a tropical cyclone, and therefore turbulence exchanges within the HBL deserve a thorough investi- gation. However, since it is dangerous and difficult to take direct measurements within the HBL, studies of the HBL turbulence processes based on direct observations are rare. Thanks to the newly developed dropwindsonde equipped with a Global Position System (GPS) receiver, it is now possible to measure wind velocities and other meteorological variables with an unprecedented accuracy and …