Recent research has shown that secondary organic aerosols (SOA) are major contributors to ultrafine particle growth to climatically relevant sizes, increasing global cloud condensation nuclei (CCN) concentrations within the continental boundary layer (BL). This thesis contains two separate studies investigating SOA characteristics and the implications of SOA on global climate. The first study investigates two critical, but uncertain, characteristics of SOA: (1) the amount of SOA available to condense and (2) the volatility or condensational behavior of SOA. The second study investigates the effect of biological volatile organic compound (BVOC) emission changes on SOA formation from preindustrial to present day, and the effect on CCN concentrations using BVOC emission estimates over the last millennium.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Aerosols have significant impacts on earth's climate and hydrological cycle. They can directly reflect the amount of incoming solar radiation into space; by acting as cloud condensation nuclei (CCN), they can indirectly impact climate by affecting cloud albedo. Our current assessment of the interactions of aerosols and clouds is uncertain and parameters used to estimate cloud droplet formation in global climate models are not well constrained. Organic aerosols attribute much of the uncertainty in these estimates and are known to affect the ability of aerosol to form cloud droplets (CCN Activity) by i) providing solute, thus reducing the equilibrium water vapor pressure of the droplet and ii) acting as surfactants capable of depressing surface tension, and potentially, growth kinetics. My thesis dissertation investigates various organic aerosol species (e.g., marine, urban, biomass burning, Humic-like Substances). An emphasis is placed on the water soluble components and secondary organic aerosols (SOA). In addition the sampled organic aerosols are acquired via different media; directly from in-situ ambient studies (TEXAQS 2006) environmental chamber experiments, regenerated from filters, and cloud water samples. Novel experimental methods and analyses to determine surface tension, molar volumes, and droplet growth rates are presented from nominal volumes of sample. These key parameters for cloud droplet formation incorporated into climate models will constrain aerosol-cloud interactions and provide a more accurate assessment for climate prediction.

The market of IOT devices continues to grow at a rapid speed as well as constrained wireless sensor networks. Today, the main network paradigm is host centric where a users have to specify which host they want to receive their data from. Information-centric networking is a new paradigm for the future internet, which is based on named data instead of named hosts. With ICN, a user needs to send a request for a perticular data in order to retrieve it. When sent, any participant in the network, router or server, containing the data will respond to the request. In order to achieve low latency between data creation and its consumption, as well as being able to follow data which is sequentially produced at a fixed rate, an algortihm was developed. This algortihm calculates and determines when to send the next interest message towards the sensor. It uses a ‘one time subscription’ approach to send its interest message in advance of the creation of the data, thereby enabling a low latency from data creation to consumption. The result of this algorithm shows that a consumer can retrieve the data with minimum latency from its creation by the sensor over an extended period of time, without using a publish/subscribe system such as MQTT or similar which pushes their data towards their consumers. The performance evaluation carried out which analysed the Content Centric Network application on the sensor shows that the application has little impact on the overall round trip time in the network. Based on the results, this thesis concluded that the ICN paradigm, together with a ’one-time subscription’ model, can be a suitable option for communication within the IoT domain where consumers ask for sequentially produced data.

Aerosol particles acting as cloud condensation nuclei (CCN) or ice nucleating parti- cles (INP) play a major role in the formation and glaciation of clouds. Thereby they exert a strong impact on the radiation budget of the Earth. Data on abundance and properties of both particle types are sparse, especially for remote areas of the world, such as the Southern Ocean (SO). In this work, unique results from ship-borne aerosol-particle-related in situ measurements and filter sampling in the summertime SO region are presented. An overview of CCN and INP number concentrations on the Southern Ocean is provided and, using additional analyses on particle chemical composition and air-mass origin, insights regarding possible CCN and INP sources and origins are presented, with the help of a correlation analysis. CCN number concentrations spanned 2 orders of magnitude, e.g. for a supersaturation of 0.3 % values ranged roughly from 3 to 590 cm⁻³. CCN showed variable contributions of organic and inorganic material. No distinct size-dependence of the CCN hygroscopicity parameter was apparent, indicating homogeneous composition across sizes (critical dry diameter on average between 30 nm and 110 nm). The relative contribution of sea spray aerosol (SSA) to the CCN number concentration was on average small (below 35 %). Ambient INP number concentrations were measured in the temperature range from −4 to −27 °C using an immersion freezing method. Concentrations spanned up to 3 orders of magnitude, e.g. at −16 °C from 0.2 to 100 m⁻³. Elevated values (above 10 m⁻³ at −16 °C) were measured when the research vessel was in the vicinity of land (excluding Antarctica). Lower, more constant concentrations were measured on the open ocean. This, along with results of backward-trajectory analyses, hints towards terrestrial and/or coastal INP sources being dominant close to ice-free (non-Antarctic) land. In pristine marine areas INP may originate from both oceanic sources and/or long range transport. A correlation analysis yielded strong correlations between sodium mass concentration and particle number concentration in the coarse mode (larger 1 µm), unsurprisingly indicating a significant contribution of SSA to that mode. CCN number concentration was highly correlated with the number concentrations of Aitken (10 to 100 nm) and accumulation mode particles (100 to 1000 nm). This, together with a lack of correlation between sodium mass and Aitken and accumulation mode number concentrations, underlines the important contribution of non-SSA, probably secondarily formed particles, to the CCN population.:1 Introduction 2 Fundamentals 2.1 Aerosol particle activation 2.1.1 Köhler theory 2.1.2 κ-Köhler theory 2.2 Ice nucleation 2.2.1 Homogeneous Freezing 2.2.2 Heterogeneous Freezing 3 Campaign, instrumentation, and data handling 3.1 Antarctic Circum-navigation Expedition 3.2 In situ aerosol measurements 3.2.1 Aerosol number size distribution 3.2.2 Cloud condensation nuclei 3.3 Off-line aerosol characterisation 3.3.1 High-volume sampling 3.3.2 Low-volume sampling 3.3.3 Ice nucleation droplet array (INDA) 3.3.4 Analysis of chemical composition 3.4 Further resources 3.4.1 In-water organic compound measurements 3.4.2 Wind measurements 3.4.3 Air-mass origin analysis 3.4.4 Fluorescent particles 3.4.5 Correlation analysis 4 Results and Discussion 4.1 Aerosol particles and cloud condensation nuclei 4.1.1 Particle number size distributions 4.1.2 CCN number concentrations 4.1.3 CCN hygroscopicity 4.1.4 Air-mass origin for aerosol particle and CCN measurements 4.2 Ice nucleating particles 4.2.1 INP abundance 4.2.2 Air-mass origin for INP measurements 4.3 Chemical composition of sampled aerosol particles 4.4 Correlation analysis 5 Summary and Conclusions / Aerosolpartikel, die als Wolkennukleations- oder Eiskeime fungieren, spielen eine Schlüsselrolle in den Entstehungs- und Vereisungsprozessen von Wolken. Mit ihren wolkenrelevanten Eigenschaften haben diese beiden Arten von Aerosolpartikeln einen starken Einfluss auf den Strahlungshaushalt der Erde. Messungen ihrer Häufigkeit und Eigenschaften sind selten, inbesondere in den entlegenen Regionen der Erde wie beispielsweise dem Südlichen Ozean. In dieser Arbeit werden die Ergebnisse von in situ und filterbasierten Partikelmessungen einer Forschungsfahrt auf dem Südlichen Ozean in den Sommermonaten der Südhalbkugel gezeigt. Ein erstmaliger Überblick über die Anzahlkonzentrationen der Wolkennukleations- und Eiskeime über dem Südlichen Ozean wird gegeben. Unter Berücksichtigung weiterer Messergebnisse zur chemischen Zusammensetzung der Partikel und Betrachtungen zur Herkunft der Luftmassen werden Rückschlüsse auf die Herkunft und Quellen der gesammelten, wolkenrelevanten Aerosolpartikel gezogen, auch mit Hilfe einer Korrelationsanalyse. Die Anzahlkonzentration der Wolkennukleationskeime schwankte innerhalb von zwei Größenordnungen, beispielsweise zwischen 3 und 590 cm⁻³ bei 0.3 % Übersättigung. Die chemische Zusammensetzung der Wolkennukleationskeime variierte dabei stark, zwischen organischem und inorganischem Material. Der Hygroskopizitätsparameter zeigte keine Größenabhängigkeit, was für eine intern gemischte Population von Wolkennukleationskeimen spricht (kritische Partikeldurchmesser lagen im Mittel zwischen 30 und 110 nm). Der prozentuale Anteil von Seesalzpartikeln zur Anzahlkonzentration der Wolkennukleationskeime war im Mittel gering (kleiner 35 %). Die Anzahlkonzentration der Eiskeime wurden im Temperaturbereich −4 bis −27 °C mittels einer filterbasierten Immersionsgefriermethode bestimmt. Die Anzahlkonzentrationen schwankten dabei im Bereich von bis zu drei Größenordnungen, beispielsweise zwischen 0.2 und 100 m⁻³ bei einer Temperatur von −16 °C. In Küstennähe, mit Ausnahme von Antarktika, wurden erhöhte Anzahlkonzen- trationen (über 10 m⁻³ bei −16 °C) gemessen. Niedrigere, weniger variable Anzahlkonzentrationen wurden hingegen auf offener See gemessen. Diese Beobachtungen, zusammen mit den Ergebnissen zur Luftmassenherkunft, sprechen für eine Dominanz von terrestrischen und/oder küstennahen Quellen der Eiskeime in der Nähe von eisfreiem (nicht-Antarktischem) Festland. Dabei können in den unbe- rührten, marinen Regionen die Eiskeime aus dem Meer selbst und/oder Ferntransport stammen. Eine Korrelationsanalyse zeigte einen starken Zusammenhang zwischen der Massenkonzentration von Natrium und der Anzahlkonzentration an groben Aerosolpartikeln (größer 1 µm). Daraus folgt ein signifikanter Anteil an Seesalzpartikeln in dieser Partikelgröße. Die Anzahlkonzentration der Wolkennukleationskeime korrelierte stark mit den Anzahlkonzentrationen der Aitken- (10 bis 100 nm) bzw. Akkumulationskerne (100 bis 1000 nm). Diese Beobachtung, zusammen mit dem Fehlen einer Korrelation zwischen Natriummasse und Aitken- oder Akkumulationskernanzahl, unterstreicht die Relevanz von Partikeln die nicht Seesalz sind (vermutlich sekundär geformten Aerosolpartikel) für die Population der Wolkennukleationskeime.:1 Introduction 2 Fundamentals 2.1 Aerosol particle activation 2.1.1 Köhler theory 2.1.2 κ-Köhler theory 2.2 Ice nucleation 2.2.1 Homogeneous Freezing 2.2.2 Heterogeneous Freezing 3 Campaign, instrumentation, and data handling 3.1 Antarctic Circum-navigation Expedition 3.2 In situ aerosol measurements 3.2.1 Aerosol number size distribution 3.2.2 Cloud condensation nuclei 3.3 Off-line aerosol characterisation 3.3.1 High-volume sampling 3.3.2 Low-volume sampling 3.3.3 Ice nucleation droplet array (INDA) 3.3.4 Analysis of chemical composition 3.4 Further resources 3.4.1 In-water organic compound measurements 3.4.2 Wind measurements 3.4.3 Air-mass origin analysis 3.4.4 Fluorescent particles 3.4.5 Correlation analysis 4 Results and Discussion 4.1 Aerosol particles and cloud condensation nuclei 4.1.1 Particle number size distributions 4.1.2 CCN number concentrations 4.1.3 CCN hygroscopicity 4.1.4 Air-mass origin for aerosol particle and CCN measurements 4.2 Ice nucleating particles 4.2.1 INP abundance 4.2.2 Air-mass origin for INP measurements 4.3 Chemical composition of sampled aerosol particles 4.4 Correlation analysis 5 Summary and Conclusions

Abstract Aerosol-cloud and aerosol-radiation interactions depend on several factors such as the physico-chemical properties, geographical and temporal variability, and vertical distribution of atmospheric aerosols. Of particular importance are cloud condensation nuclei (CCN) and black carbon (BC) particles as a subset of the atmospheric aerosol population. CCN are a prerequisite for cloud droplet formation, and variations in CCN loading can modify cloud properties. BC can efficiently absorb solar radiation, induce local heating and inhibit cloud formation. In order to determine the effects of CCN and BC on clouds, precipitation, radiation and the Earth’s energy budget, atmospheric loading and spatio-temporal distribution of aerosols are highly relevant. Thus this dissertation addresses and helps to elucidate the spatio-temporal variation and co-variability of CCN and BC with extensive field measurement data from aircraft and ground-based measurements. The data analyses focus on anthropogenic pollution, wildfire emissions and volcanic aerosols. In the Anthropocene, the distribution and abundance of atmospheric aerosols have changed drastically. Major sources of anthropogenic particulate pollution are the combustion of fossil fuels and biofuels as well as emissions from open biomass burning. The ubiquitous presence of anthropogenic air pollution, especially over continental regions in the Northern Hemisphere, hampers the assessment of anthropogenic influence on aerosol and climate due to a lack of unperturbed reference measurements. The abrupt reduction in human activities during the first COVID-19 lockdown created unprecedented atmospheric conditions that allowed us to investigate and quantify changes in the tropospheric composition in response to changes in anthropogenic emissions. The results reflect a strong and immediate influence of human activities on air quality, the role of BC as a major air pollutant in the Anthropocene, and close links between the atmospheric burdens of CCN and BC. Measurement data from five aircraft missions in polluted environments reveal characteristic relationships between CCN and BC in urban haze from Europe and East Asia, highly aged biomass burning smoke over the tropical Atlantic and the Amazon rainforest, and lightly aged biomass burning smoke over Europe, Brazil, and Asia. Over Europe and Asia, the vertical distribution of CCN in the lower troposphere up to altitudes about 5 km is highly sensitive to regional anthropogenic emissions. Over the tropical Atlantic ocean, the vertical distribution is strongly influenced by the longrange transport of mineral dust and biomass burning smoke, but volcanic eruptions also contribute to the aerosol load.

We present here the first cloud condensation nuclei (CCN) concentration profiles derived from measurements with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), for different aerosol types at a supersaturation of 0.15%. CCN concentrations, along with the corresponding uncertainties, were inferred for a nighttime CALIPSO overpass on 9 September 2011, with coincident observations with the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft, within the framework of the Evaluation of CALIPSO’s Aerosol Classification scheme over Eastern Mediterranean (ACEMED) research campaign over Thessaloniki, Greece. The CALIPSO aerosol typing is evaluated, based on data from the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis. Backward trajectories and satellite-based fire counts are used to examine the origin of air masses on that day. Our CCN retrievals are evaluated against particle number concentration retrievals at different height levels, based on the ACEMED airborne measurements and compared against CCN-related retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors aboard Terra and Aqua product over Thessaloniki showing that it is feasible to obtain CCN concentrations from CALIPSO, with an uncertainty of a factor of two to three.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal. / Le développement de l’identité régionale dans la région de la capitale nationale fut l’objet de problématiques diverses. Ce développement identitaire eut même des répercussions au niveau de l’aménagement de son territoire. Depuis plus d’un siècle, plusieurs événements survenus sur la scène politique, économique, sociale et culturelle ont eu un impact sur l’aménagement de la région. En 1946, le gouvernement canadien fit appel à Jacques Gréber, un architecte aménagiste d’origine française, afin de réaliser un plan d’aménagement pour le territoire de la capitale nationale. Ses propositions d’aménagement suggéraient une relocalisation des équipements industriels et ferroviaires en périphérie du centre-ville ainsi qu’un reverdissement et une mise en valeur des berges et cours d’eau de la région. De plus, ces recommandations visaient parallèlement à développer une capitale où l’aménagement reflèterait une identité pancanadienne. Le projet de Gréber ne fut cependant pas réalisé intégralement. Afin de comprendre le développement de la région, nous ferrons appel à certains éléments de la géographie structurale. Cette approche théorique permettra de révéler la présence d’une structure sous-jacente au territoire, ayant influencé le développement urbain. La configuration de cette structure fut, elle aussi, influencée par les changements sociaux survenus au sein de la population. Ces derniers eurent un impact sur la perception qu’avait la population sur son environnement et par conséquent sur la réalisation d’aménagements sur le territoire. Finalement, une comparaison entre les volontés d’aménagements de Gréber et la structure sous-jacente permettra d’expliquer les résultats de la réalisation du Plan Gréber et d’autres projets plus récents. / The development of regional identity in the National Capital Region has been at the centre of a variety of issues, it even had repercussions on regional urban planning. Since the late 19th century, many events that occurred in the political, economic, social and cultural spheres have had major impacts on the urban development of the region. In the middle of the 20th century, the Canadian government asked Jacques Gréber, a French planner and architect, to propose a plan for the National Capital Region. The plan suggested that all industrial and railroad equipment should be relocated outside the downtown area and that the esthetical aspect of the shores and the rivers be improved. Furthermore, these recommendations had a parallel objective of promoting a Canadian identity through the urban planning. The current layout of the region reveals that Greber’s plan was not fully implemented. To understand the development of the region, we will refer to certain elements of the structural geography theory. This theoretical approach will reveal a subjacent structure that influenced the urban development. The configuration of this structure was also influenced by social change occurring in the population. These changes had an impact on the population’s perception of its environment and consequently on planning and implementation. Finally, a comparison of Gréber’s development plans and the subjacent structure revealed by the morphogenetic path of urban development, provided by the structural geography theory, will allow for the explanation of the results of the implementation of Greber’s plan and other more recent planning projects.

在大型天然災害發生之後的黃金救援時期，災民存活率和救災效益之提昇極度仰賴於一個順暢的通訊系統。由歷年來大型災變的經驗中我們可知，行動通訊系統其實是不可靠且極為脆弱的，基地台之電力供應中斷或連接後端固定網路線路（Backhaul）之損毀都將使得通訊系統癱瘓而影響救災工作效率。 本研究提出一種新的應急通訊系統，利用原有行動通訊系統中未損毀但失去連網能力的基地台，藉由臨時供應的電力恢復其運轉，並以無線通訊設備與鄰近基地台互連建構一個臨時應急性的網路，稱為應急蜂巢式行動通訊網路（Contingency Cellular Network，CCN），供災區內手機用戶進行通訊。由於災區內部通訊的對象通常是一個特定的群組角色，而非一個特定人員，而災民與救災人員也不知彼此所在位置及聯絡的方式，因此無法以平常的撥號方式發起呼叫。本研究以CCN網路架構為基礎，設計並實作群組通訊模式，讓災區內人員以簡碼方式向任一群組發起呼叫並建立通話。 為驗證CCN群組通訊設計之可行性及效能，我們以IEEE802.11 Wi-Fi無線網路環境建置模擬系統，並以Android平台手機搭配VoIP軟體模擬手機與系統連線以進行通話。最後設計了一連串的實驗評估本模擬系統之效能。從實驗結果可知，本系統可於短時間內即時回應使用者註冊需求及完成通話連線處理；當通話數在30通以下時，Mouth-to-Ear Delay (MED) 值可維持在400ms以下，語音品質控制在一般VoIP使用者可容許的範圍之內。本實驗可作為未來改進系統功能和建置架構之參考依據。 / When stricken by a catastrophic natural disaster, the efficiency of disaster response operation is very critical to life saving. The efficiency of disaster response operation is greatly depending on communication systems. However, they were usually not dependable, including cellular networks, and often crashed due to power outage and backhaul link breakage. The failure of communication systems caused a big coordination problem to many disaster response operations. This thesis proposes a Contingency Cellular Network (CCN) by connecting isolated base stations to survival base stations using long-range wireless links to restore part of cellular network functionality. People can use their own cell phones for emergency communication in the disaster areas. CCN will be able to support many disaster response workers in the early hours of catastrophic natural disasters, thus to save many lives. Since the receiver of a phone call in a disaster area is usually a resource (agent), not a particular person, we designed a special Agency communication mode for CCN allowing CCN users to initiate a phone call to a nearby resource by dialing a designated agency number, instead of a real phone number. To verify our design, we implemented an emulated CCN system using an IEEE 802.11 Wireless LAN to mimic the CCN network and Android small phones with VoIP software to mimic user terminals. Finally, we conducted a series of experiments to evaluate the performance of the emulated system. The experimental results show that the emulated system can respond promptly to the user registration and call set-up requests. Mouth-to-Ear Delay (MED) can be effectively controlled below 400 ms when there is no more than 30 calls originated. This system may be used as reference for the future development of contingency communication networks.

It is well known that atmospheric aerosols provide the sites for forming cloud droplets, and can affect the Earth's radiation budget through their interactions with clouds. The ability of aerosols to act as cloud condensation nuclei is a strong function of their chemical composition and size. The compositional complexity of aerosol prohibits their explicit treatment in atmospheric models of aerosol-cloud interactions. Nevertheless, the cumulative impact of organics on CCN activity is still required, as carbonaceous material can constitute up to 90% of the total aerosol, 10-70% of which is water soluble. Therefore it is necessary to characterize the water soluble organic carbon fraction by CCN activation, droplet growth kinetics, and surface tension measurements. In this thesis, we investigate the water soluble properties, such as surface tension, solubility, and molecular weight, of laboratory and ambient aerosols and their effect on CCN formation. A mechanism called Curvature Enhanced Solubility is proposed and shown to explain the apparent increased solubility of organics. A new method, called Köhler Theory Analysis, which is completely new, fast, and uses minimal amount of sample was developed to infer the molar volume (or molar mass) of organics. Due to the success of the technique in predicting the molar volume of laboratory samples, it was applied to aerosols collected in Mexico City. Additionally the surface tension, CCN activity, and droplet growth kinetics of these urban polluted aerosols were investigated. Studies performed for the water soluble components showed that the aerosols in Mexico City have surfactants present, can readily become CCN, and have growth similar to ammonium sulfate. Finally, aerosols from three different polluted sources, urban, bovine, and ship emissions, were collected and characterized. The data assembled was used to predict CCN concentrations and access our understanding of the system. From these analyses, it was evident that knowledge of the chemical composition and mixing state of the aerosol is necessary to achieve agreement between observations and predictions. The data obtained in this thesis can be introduced and used as constraints in aerosol-cloud interaction parameterizations developed for global climate models, which could lead to improvements in the indirect effect of aerosols.