Investigating Marine Boundary Layer Aerosol Budgets and Variability

Thesis (Master's)--University of Washington, 2016-08

Measurements of small ice crystals in arctic cirrus: observations from the Indirect and Semi-Direct Aerosol Campaign (ISDAC)

In-situ observations on the size and shape of particles in arctic cirrus are less common than those in mid-latitude and tropical cirrus with considerable uncertainty about the contributions of small ice crystals (maximum dimension D<50 µm) to the mass and radiative properties that impact radiative forcing. In situ measurements of small ice crystals in arctic cirrus were made during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 during transits of the National Research Council of Canada Convair-580 between Fairbanks and Barrow, Alaska and during Mixed Phase Arctic Cloud Experiment (MPACE) in October 2004 with the University of North Dakota (UND) Citation over Barrow, Alaska. Concentrations of small ice crystals with D < 50 μm from a Cloud and Aerosol Spectrometer (CAS), a Cloud Droplet Probe (CDP), a Forward Scattering Spectrometer Probe (FSSP), and a two-dimensional stereo probe (2DS) were compared as functions of the concentrations of crystals with D > 100 μm measured by a Cloud Imaging Probe (CIP) and two-dimensional stereo probe (2DS) in order to assess whether the shattering of large ice crystals on protruding components of different probes artificially amplified measurements of small ice crystal concentrations. The dependence of the probe comparison on other variables as CIP N>100 (number concentrations greater than diameter D>100 μm),temperature, relative humidity respect to ice (RHice), dominant habit from the Cloud Particle Imager (CPI), aircraft roll, pitch, true air speed and angle of attack was examined to understand potential causes of discrepancies between probe concentrations. Data collected by these probes were also compared against the data collected by a CAS, CDP and CIP during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) and by a CAS and 2DS during the Tropical Composition, Cloud and Climate Coupling (TC4) missions. During ISDAC, the CAS and FSSP both overestimated measurements of small ice crystals compared to both the CDP and 2DS by 1-2 orders of magnitude. Further, the amount of overestimation increased with the concentrations from the CIP2 (N>100 > 0.1 L-1). There was an unexplained discrepancy in concentrations of small crystals between the CDP and 2DS during ISDAC. In addition, there was a strong dependence on RHice of the average ratios of the N3-50, CAS/N3-50,CDP, N3-50, FSSP096/N3-50,CDP, N3-50, CAS/N3-50,FSSP096, N10-50, CDP/N3-50,2DS, N10-50, FSSP096/N10-50,2DS. Continued studies are needed to understand the discrepancy of these probes.

Aerosol transport in a bifurcating tube at cyclic flow

Branching tube flow is a common feature of many fields of science and technology, and occurs both in animate and inanimate systems [1]. The transport of aerosol particles is of particular importance in industrial flow networks but also for the respiratory tree [2]. In this analysis a 3-D numerical study is performed to investigate transport and deposition of aerosol particles in branching tubes. Bifurcation tubes designed according to Hess-Murray law [3] but with different branching angles are analyzed. This study covers cyclic flow conditions at frequencies of 0.25 Hz, 0.50 Hz and 0.75 Hz, Stokes numbers ranging between 0.03 and 0.25, and Reynolds numbers up to 3000.

A study of the effect of molecular and aerosol conditions in the atmosphere on air fluorescence measurements at the Pierre Auger Observatory

The air fluorescence detector of the Pierre Auger Observatory is designed to perforin calorimetric measurements of extensive air showers created by Cosmic rays of above 10(18) eV. To correct these measurements for the effects introduced by atmospheric fluctuations, the Observatory contains a group Of monitoring instruments to record atmospheric conditions across the detector site, ail area exceeding 3000 km(2). The atmospheric data are used extensively in the reconstruction of air showers, and are particularly important for the correct determination of shower energies and the depths of shower maxima. This paper contains a summary of the molecular and aerosol conditions measured at the Pierre Auger Observatory since the start of regular operations in 2004, and includes a discussion of the impact of these measurements oil air shower reconstructions. Between 10(18) and 10(20) eV, the systematic Uncertainties due to all atmospheric effects increase from 4% to 8% in measurements of shower energy, and 4 g cm(-2) to 8 g cm(-2) in measurements of the shower maximum. (C) 2010 Elsevier B.V. All rights reserved.

Multi-sensor Cloud and Aerosol Retrieval Simulator and Its Applications

Executing a cloud or aerosol physical properties retrieval algorithm from controlled synthetic data is an important step in retrieval algorithm development. Synthetic data can help answer questions about the sensitivity and performance of the algorithm or aid in determining how an existing retrieval algorithm may perform with a planned sensor. Synthetic data can also help in solving issues that may have surfaced in the retrieval results. Synthetic data become very important when other validation methods, such as field campaigns,are of limited scope. These tend to be of relatively short duration and often are costly. Ground stations have limited spatial coverage whilesynthetic data can cover large spatial and temporal scales and a wide variety of conditions at a low cost. In this work I develop an advanced cloud and aerosol retrieval simulator for the MODIS instrument, also known as Multi-sensor Cloud and Aerosol Retrieval Simulator (MCARS). In a close collaboration with the modeling community I have seamlessly combined the GEOS-5 global climate model with the DISORT radiative transfer code, widely used by the remote sensing community, with the observations from the MODIS instrument to create the simulator. With the MCARS simulator it was then possible to solve the long standing issue with the MODIS aerosol optical depth retrievals that had a low bias for smoke aerosols. MODIS aerosol retrieval did not account for effects of humidity on smoke aerosols. The MCARS simulator also revealed an issue that has not been recognized previously, namely,the value of fine mode fraction could create a linear dependence between retrieved aerosol optical depth and land surface reflectance. MCARS provided the ability to examine aerosol retrievals against “ground truth” for hundreds of thousands of simultaneous samples for an area covered by only three AERONET ground stations. Findings from MCARS are already being used to improve the performance of operational MODIS aerosol properties retrieval algorithms. The modeling community will use the MCARS data to create new parameterizations for aerosol properties as a function of properties of the atmospheric column and gain the ability to correct any assimilated retrieval data that may display similar dependencies in comparisons with ground measurements.

Caracterización del mucilago de cacao CCN 51 mediante espectrofotometría UV-visible y absorción atómica” caso: Ecuador-zona 6

Más de 12000 m3 de mucilago de cacao CCN-51 son producidos y abandonados en las fincas de cacao en el Ecuador cada año. El estudio tiene como objetivo caracterizar este residuo en la Zona 6. Las muestras se obtuvieron de 10 lugares dentro de la zona de estudio, las mismas que están geo referenciadas. Para el análisis se usó espectrofotometría UV-Visible para la identificación de azucares reductoras totales, y espectrofotometría de absorción atómica para identificar minerales. Además se determinó parámetros físicos. Los resultados de los análisis fueron los siguientes: pH 4.05±0.004, los sólidos solubles fue de 17.15±0.86 0Brix, la acidez Titulable fue 245.25±21.19 meq/L. Por otra parte las azucares reductoras totales fueron de 1228.82±178.52 g/L y los de calcio, sodio y potasio fueron de 169.21±31.04 mg/L, 161.85±40.41 mg/L, 462.9±49.96 mg/L respectivamente. Se analizó una muestra mediante espectroscopia de infrarrojo para identificar glucosa y sacarosa, los resultados de este análisis fueron 398 g/L, 800g/l, posteriormente se realizó un análisis t student con el resultado obtenido en espectrofotometría UV-Visible de las azucares reductoras totales, como resultado final se estableció que no existe diferencia significativa entre las dos técnicas instrumentales.

Modeling the Effect of Vapor Wall Deposition on the Formation of Secondary Organic Aerosol in Chamber Studies

Laboratory chamber experiments are used to investigate formation of secondary organic aerosol (SOA) from biogenic and anthropogenic precursors under a variety of environmental conditions. Simulations of these experiments test our understanding of the prevailing chemistry of SOA formation as well as the dynamic processes occurring in the chamber itself. One dynamic process occurring in the chamber that was only recently recognized is the deposition of vapor species to the Teflon walls of the chamber. Low-volatility products formed from the oxidation of volatile organic compounds (VOCs) deposit on the walls rather than forming SOA, decreasing the amount of SOA formed (quantified as the SOA yield: mass of SOA formed per mass of VOC reacted). In this work, several modeling studies are presented that address the effect of vapor wall deposition on SOA formation in chambers.

A coupled vapor-particle dynamics model is used to examine the competition among the rates of gas-phase oxidation to low volatility products, wall deposition of these products, and mass transfer to the particle phase. The relative time scales of these rates control the amount of SOA formed by affecting the influence of vapor wall deposition. Simulations show that an effect on SOA yield of changing the vapor-particle mass transfer rate is only observed when SOA formation is kinetically limited. For systems with kinetically limited SOA formation, increasing the rate of vapor-particle mass transfer by increasing the concentration of seed particles is an effective way to minimize the effect of vapor wall deposition.

This coupled vapor-particle dynamics model is then applied to α-pinene ozonolysis SOA experiments. Experiments show that the SOA yield is affected when changing the oxidation rate but not when changing the rate of gas-particle mass transfer by changing the concentration of seed particles. Model simulations show that the absence of an effect of changing the seed particle concentration is consistent with SOA formation being governed by quasi-equilibrium growth, in which gas-particle equilibrium is established much faster than the rate of change of the gas-phase concentration. The observed effect of oxidation rate on SOA yield arises due to the presence of vapor wall deposition: gas-phase oxidation products are produced more quickly and condense preferentially onto seed particles before being lost to the walls. Therefore, for α-pinene ozonolysis, increasing the oxidation rate is the most effective way to mitigate the influence of vapor wall deposition.

Finally, the detailed model GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) is used to simulate α-pinene photooxidation SOA experiments. Unexpectedly, α-pinene OH oxidation experiments show no effect when changing either the oxidation rate or the vapor-particle mass transfer rate, whereas GECKO-A predicts that changing the oxidation rate should drastically affect the SOA yield. Sensitivity studies show that the assumed magnitude of the vapor wall deposition rate can greatly affect conclusions drawn from comparisons between simulations and experiments. If vapor wall loss in the Caltech chamber is of order 10^-5 s^-1, GECKO-A greatly overpredicts SOA during high UV experiments, likely due to an overprediction of second-generation products. However, if instead vapor wall loss in the Caltech chamber is of order 10^-3 s^-1, GECKO-A greatly underpredicts SOA during low UV experiments, possibly due to missing autoxidation pathways in the α-pinene mechanism.

Von der Minderheit zur Mehrheit? Psycho-soziale Einflüsse bei der Verbreitung klima-schonender Innovationen

Vor dem Hintergrund des Klimawandels und weiterer Zukunftsherausforderungen stellt sich in drängenderem Maße die Frage, wie der Wandel zu einer nachhaltigen Gesellschaft gelingen kann. Im Zuge dessen rücken zunehmend solche Lösungsansätze in den Fokus, die an der Schnittstelle von technischen und sozialen Systemen nachhaltige und klimaschonende Innovationen entwickeln. Die vorliegende Dissertation beschäftigte sich in diesem Kontext mit der Frage, welche psychologischen und sozialen Faktoren und Mechanismen bei der individuellen Übernahme (Adoption) klimaschonender Innovationen von Bedeutung und für deren weitere Verbreitung (Diffusion) förderlich sind. Auf theoretischer und konzeptioneller Ebene wurden einerseits persönliche Eigenschaften von Adoptern wie der eigene Lebens- und Informationsverarbeitungsstil und andererseits die Charakteristika klimaschonender Innovationen und deren individuelle Wahrnehmung und Bewertung betrachtet und in einem umfassenden Modell integriert. Die Arbeit untersuchte zunächst mit Hilfe einer breit angelegten Fragebogenstudie (N = 778), wie weit die Innovationen Bezug von Ökostrom und Beteiligung an Bürger-Solaranlagen in verschiedenen sozialen Milieus bereits verbreitet waren und wie diese in milieuspezifischer Perspektive beurteilt und kommunikativ rezipiert wurden. Mittels Strukturgleichungsmodellierung wurde untersucht, inwiefern sich die Bewertungs- und Entscheidungsstrukturen von frühen und späteren Adoptern unterschieden. Es zeigten sich klare milieuspezifische Schwerpunkte: Personen aus dem postmateriellen und den hedonistischen Milieus bewerteten diese Innovationen positiver und waren häufiger unter den Adoptern zu finden als traditionelle und Mainstream-Milieus. Zudem deuteten die Ergebnisse auf eine stärker deliberativ ausgeprägte Entscheidungsstruktur bei frühen Adoptern hin – zumindest hinsichtlich des Bezugs von Ökostrom, der zum Zeitpunkt der Untersuchung bereits weiter verbreitet war als die Beteiligung an Bürger-Solaranlagen. In einer ergänzenden experimentellen Erhebung (N = 356) wurden die Teilnehmende zufällig einer von drei Untersuchungsbedingungen zugeordnet: In einem Informationstext über Smart Meter war eine (fingierte) entweder starke soziale Norm (Mehrheitsbedingung), eine schwache soziale Norm (Minderheitsbedingung) oder keine derartige soziale Information (Kontrollbedingung) enthalten. In einem nachfolgenden Test auf Wissenstransfer – als Indikator der Informationsverarbeitungstiefe – schnitten Personen mit geringerem Interesse an Smart Metern (also solche, die keine weiteren Informationen nachfragten) in der Mehrheitsbedingung am besten ab, wohingegen Personen mit größerem Interesse (fragten weitere Informationen nach) in der Minderheitsbedingung die beste Leistung erzielten. Auch diese Ergebnisse deuten auf unterschiedliche Informationsverarbeitungs- und Entscheidungsstrukturen je nach Wahrnehmung des bisherigen Verbreitungsgrads in Interaktion mit persönlichen Dispositionen hin. Aus den Ergebnissen lassen sich vielfältige Implikationen für ein verbessertes Marketing klimaschonender Innovationen, die umweltpolitische Praxis und für die weitere Forschung ableiten. Es wird empfohlen, bei der Kommunikation (z.B. im Rahmen zielgruppenspezifischer Kampagnen) soziale Normen und deren differentielle Wirkung auf die Verarbeitung innovationsbezogener Informationen gezielter zu nutzen. Da unter den aktuellen Rahmenbedingungen mit keiner hundertprozentigen Diffusion der betrachteten Innovationen in alle gesellschaftlichen Gruppen hinein zu rechnen ist, werden auf politischer Ebene neben „weichen“ politischen Instrumenten auch fiskalische oder ordnungsrechtliche Maßnahmen erforderlich sein. Schließlich erscheint es sinnvoll, sich in der weiteren Forschung stärker mit kommunikativen Prozessen wie beispielsweise Meinungsführerschaft oder dem Einfluss von Medienkampagnen und medialer Berichterstattung auseinander zu setzen.

Comparisons of an aerosol transport model with a 4-year analysis of summer aerosol optical depth retrievals over the Canadian Arctic

Abstract : This is a study concerning comparisons between the Dubovik Aerosol optical depth (AOD) retrievals from AEROCAN (ARONET) stations and AOD estimates from simulations provided by a chemical transport model (GEOS-Chem : Goddard Earth Observing System Chemistry). The AOD products associated with the Dubovik product are divided into total, fine and coarse mode components. The retrieval period is from January 2009 to January 2013 for 5 Arctic stations (Barrow, Alaska; Resolute Bay, Nunavut; 0PAL and PEARL (Eureka), Nunavut; and Thule, Greenland). We also employed AOD retrievals from 10 other mid-latitude Canadian stations for comparisons with the Arctic stations. The results of our investigation were submitted to Atmosphere-Ocean. To briefly summarize those results, the model generally but not always tended to underestimate the (monthly) averaged AOD and its components. We found that the subdivision into fine and coarse mode components could provide unique signatures of particular events (Asian dust) and that the means of characterizing the statistics (log-normal frequency distributions versus normal distributions) was an attribute that was common to both the retrievals and the model.