To assess information about the optical, microphysical, and radiative properties of aerosol particles the lidar technique and sun photometers are commonly used. Information that result from both lidar and sun photometer data can provide a distinct image of the vertical aerosol properties. The algorithm developed at the Institute of Physics of the National Academy of Science of Belarus (IPNASB) uses lidar measurements at the three wavelengths 355, 532, and 1064 nm and mean backscatter and extinction coefficients retrieved from radiometric data to obtain profiles of fine-mode and coarse-mode concentrations. Within the master thesis the IPNASB algorithm was tested for specific aerosol situations. Three cases are considered representing Saharan dust, smoke and industrial aerosol from East Europe, and volcanic aerosol from the Eyjafjallajokull eruption. The retrieved microphysical aerosol properties are in good to acceptable agreement with findings of well-established methods.

In this thesis the occurrence and the properties of atmospheric particles within Europe are studied by means of the regional transport model COSMO-MUSCAT (Consortium for Small-scale Modeling - MultiScale Atmospheric Transport Model). The model is used to perform calculations for a summer (19-26 July 2006) and a winter (16-26 February 2007) period. Individual extinction coefficients are computed taking into account hygroscopic growth and mass extinction efficiencies of specific chemical compounds. The model study focuses on vertical backscatter profiles, aerosol optical depths, particle surface concentrations and radiative effects. Different descriptions of the vertical distribution of chemical compounds at the lateral model boundaries are tested. The results show that for the tested model setup the influence of the aerosol distribution at the model boundaries on European aerosol is limited. Information from lidar profiles may improve the description at the lateral model boundaries. This may be more important for smaller model domains. Space-based lidar (light detection and ranging) observations (CALIOP - Cloud-Aerosol Lidar with Orthogonal Polarization) observations are compared to the simulated backscatter profiles caused by the simulated anthropogenic aerosol. The model reproduces the shape and magnitude of the vertical backscatter profiles well for both time periods. Better agreements are found for night-time observations compared to day-time data. Satisfying agreements between the model results and experimental observations of ground-based vertical backscatter profiles, aerosol optical depths and particle surface concentrations are also found for the two time periods in Europe. Discrepancies between measurement and simulation highlight the difficulties to describe horizontal and vertical aerosol properties properly. The direct and semi-direct radiative effects of the absorbing aerosol are studied for both summer and winter period. For both periods, an increase of the solar heating rate due to the aerosol forcing is determined. This heating leads to an average decrease of the total cloud cover of 1.0% (summer) and of 0.7% (winter). This semi-direct radiative effect causes a positive forcing at the surface and at the top-of-atmosphere in the European domain.

The knowledge of the optical and microphysical properties of aerosol particles in the atmosphere is relevant in various scientific fields from public health issues to climate modeling. A retrieval method is presented that estimates the single scattering albedo and asymmetry parameter of aerosol particles in regions of high pollution using spectral ground-based radiance and irradiance measurements, radiative transfer simulations, and a priori knowledge of the aerosol optical depth (AOD) derived from sun photometer observations. The used measurement data originated from the Pearl River Delta in China. The results are compared with sun photometer data and show a high agreement for AODs larger than 0.5. For low AODs and for cloudy conditions the method did not work due to the strong sensitivity of the initial parameters. / Kenntnisse über optische und mikrophysikalische Eigenschaften von Aerosolpartikeln in der Atmosphäre werden in vielen verschiedenen wissenschaftlichen Gebieten benötigt. Diese reichen vom Gesundheitswesen bis hin zur Klimamodellierung. Deswegen wird im Folgenden eine Ableitungsmethode vorgestellt, die die Einfachstreualbedo und Asymmtrieparameter von Aerosolpartikeln bestimmt. Diese Methode wurde dabei für Messungen im Pearl River Delta, China, in denen oft hohe Luftverschmutzungen auftreten, angewandt. Es werden dazu bodengebundene Messungen der spektralen abwärtsgerichteten Strahlungsflussdichte und Strahldichte, gekoppelt mit Strahlungsübertragungsrechnungen durchgeführt. Um die aerosoloptischen Parameter ableiten zu können, wird als zusätzliche Randbedingung die aerosol-optische Dicke (AOD) benötigt. Sonnenphotometermessungen liefern dabei zum einen die AOD und zum anderen die aerosoloptische Eigenschaften, die mit den Ergebnissen der Ableitungsmethode verglichen werden. Dabei wurden für große AOD-Werte (über 0.5) gute Übereinstimmungen zwischen beiden Methoden festgestellt werden. Für AOD-Werte kleiner als 0.5 und bei bewölkten Bedingungen zeigt die Methode große Unsicherheiten, weil die Parameter zu empfindlich auf diese Begebenheiten reagieren.

In diesem Beitrag werden Ansätze beschrieben, wie man aus flugzeuggetragenen Messungen von Eigenschaften atmosphärischer Extingenten die für Strahlungstransportrechnungen notwendigen Größen und Parameter rekonstruieren kann. Angewendet wird das Programm zur ersten Auswertung für bezüglich der Strahlung verschiedene atmosphärische Situationen. Die Daten hierzu wurden auf der ersten Messkampagne des Projektes INSPECTRO gesammelt. Es zeigt sich für den Fall einer Atmosphäre mit stratiformer Bewölkung eine gute Übereinstimmung mit den Messungen. Eine genaue Berechnung der Extinktion durchWolken mittels Tropfenspektren bringt derzeit keine Vorteile gegenüber einer einfachen Parametrisierung. Für den Fall eines durchbrochenen Wolkenfeldes ergeben sich lokal große Unterschiede zwischen Simulation und Messung. Dennoch läßt sich zeigen, daß die gemessenen und berechneten Felder des aktinischen Flusses einander sehr ähnliche statistische Eigenschaften haben. / In this article some methods to reconstruct an artificial three-dimensional atmosphere from flight measurement data are described. The artificial atmosphere shall accurately represent the scattering properties of the real atmosphere, that are necessary to perform radiative transfer simulations. The method is applied to conduct a preliminary analysis of several atmospheric situations corresponding to different sets of radiative properties. The analyzed measurement data was collected during the first measurement campaign within the INSPECTRO project. In the case of an atmosphere containing a stratiform cloud layer, the measurements and simulation results are in very good agreement. A more accurate calculation of the extinction of radiation within the clouds by way of accounting for measured droplet spectra does momentarily not lead to an improvement in comparison with the simple parameterization method. In the case of a broken cloud field the significant local discrepancies between the measurement data and simulation results are to be noted. Nevertheless it can be shown that the statistical properties of the measured and calculated actinic flux fields resemble each other very closely.

The research in this dissertation explored the sources and chemistry of organic nitrogen aerosols in the atmosphere. Two approaches were employed: field measurements and laboratory experiments. In order to characterize atmospheric aerosol, two ambient studies were conducted in Cache Valley in Northern Utah during strong winter inversions of 2004 and 2005. The economy of this region is heavily dependent on agriculture. There is also a fast growing urban population. Urban and agricultural emissions, aided by the valley geography and meteorology, led to high concentrations of fine particles that often exceeded the national ambient air quality standards. Aerosol composition was dominated by ammonium nitrate and organic species. Mass spectra from an aerosol mass spectrometer revealed that the organic ion peaks were consistent with reduced organic nitrogen compounds, typically associated with animal husbandry practices. Although no direct source characterization studies have been undertaken in Cache Valley with an aerosol mass spectrometer, spectra from a study at a swine facility in Ames, Iowa, did not show any evidence of reduced organic nitrogen species. This, combined with temporal and diurnal characteristics of organic aerosol peaks, was a pointer that the organic nitrogen species in Cache Valley likely formed from secondary chemistry. Application of multivariate statistical analyses to the organic aerosol spectra further supported this hypothesis. To quantify organic nitrogen signals observed in ambient studies as well as understand formation chemistry, three categories of laboratory experiments were performed. These were calibration experiments, smog chamber studies, and an analytical method development. Laboratory calibration experiments using standard calibrants indicated that quantifying the signals from organic nitrogen species was dependent on whether they formed through acid-base chemistry or via secondary organic aerosol pathway. Results from smog chamber reactions of amines with ozone, nitrogen oxides, nitrate radical, and nitric acid showed that the secondary organic aerosol pathway was more plausible than acid-base chemistry, thus making the contribution of the organic nitrogen species to the total aerosol mass in Cache Valley significant. Gas phase and aerosol products formed from the smog chamber reactions were identified and used to devise reaction mechanisms. Finally, an ion chromatographic method for detecting and quantifying some key organic nitrogen species in aerosol was developed and tested.

The marine stratocumulus clouds are highly sensitive to aerosol perturbations. In this study, we have explored the cloud susceptibility to aerosol using satellite observation and multi-model simulations over the Southeast Pacific Ocean (SEP). The climatology of satellite observation indicates that SEP is a relatively clean area with low aerosol optical depth (AOD). The SEP is a region of marine stratocumulus deck with cloud fraction (CF) reaching as high as 90% in many regions, with relatively low (140 cm−3) cloud droplet number concentration (CDNC) over the marine environment, and it increases as it moves towards the coast. The joint histogram analysis shows that the AOD-CDNC relation shows positive sensitivity and a non-linear CDNC-LWP (liquid water path) relationship; however, a negative sensitivity is dominant. The multimodel analysis shows that most models have a strong positive AOD-CDNC sensitivity, suggesting that the cloud albedo effect leads to net cooling. The general circulation models (GCM) reveal a negative radiative forcing (-0.28 to -1.36Wm−2) at the top of the atmosphere (TOA) when using the flux method. It supports the positive AODCDNC sensitivity and the resulting negative radiative forcing in GCMs. However, the CDNC-LWP shows a diverse relation in the models. In the GCMs, the effect of cloud microphysics is not considered while estimating the net radiative forcing. To include the effect of cloud microphysics in the radiative forcing estimates, we have proposed a statistical approach to calculate the net radiative forcing. The results show that the net radiative forcing is sensitive to the LWP change due to the aerosol perturbation. / Die marinen Stratocumulus-Wolken reagieren sehr empfindlich auf Aerosol-Störungen. In dieser Studie haben wir die Anfälligkeit der Wolken für Aerosol anhand von Satellitenbeobachtungen und Multi-Modellsimulationen über dem Südostpazifik (SEP) untersucht. Die Klimatologie der Satellitenbeobachtung zeigt, dass der SEP ein relativ sauberes Gebiet mit geringer Aerosol optischer Dicke (AOD) ist. Der SEP ist eine Region mit mariner Stratocumulus-Decke mit einer Wolkbedeckungsgrad (CF), der in vielen Regionen bis zu 90% erreicht, mit einer relativ niedrigen (140 cm−3) Wolkentröpfchenanzahlkonzentration (CDNC) über der marinen Umgebung, und sie nimmt in Richtung Küste zu. Die gemeinsame Histogramm-Analyse zeigt, dass die AOD-CDNC-Beziehung eine positive Sensitivität und eine nicht-lineare CDNC-LWP-Beziehung (Flüssigwasserpfad) aufweist; allerdings ist eine negative Sensitivität vorherrschend. Die Multi-Modellanalyse zeigt, dass die meisten Modelle eine stark positive AOD-CDNC-Empfindlichkeit aufweisen, was darauf hindeutet, dass der Wolkenalbedo-Effekt eine Nettokühlung bewirkt. Die allgemeinen Zirkulationsmodelle (GCM) zeigen einen negativen Strahlungsantrieb (-0,28 bis -1,36Wm−2) am Oberrand der Atmosphäre (TOA), wenn die Flussmethode verwendet wird. Dies unterstützt die positive AOD-CDNC-Empfindlichkeit und den daraus resultierenden negativen Strahlungsantrieb in GCMs. Der CDNC-LWP zeigt jedoch unterschiedliche Abhängigkeiten in den Modellen. In den GCMs wird die Wirkung der Wolkenmikrophysik bei der Abschätzung des Netto-Strahlungsantriebs nicht berücksichtigt. Um die Auswirkungen der Wolkenmikrophysik auf den Strahlungsantrieb einzubeziehen, haben wir einen statistischen Ansatz zur Berechnung des Nettostrahlungsantriebs gewählt. Die Ergebnisse zeigen, dass der Nettostrahlungsantrieb empfindlich auf die LWP-Änderung durch die Aerosolstörung reagiert.

Aerosol-cloud interactions are a major uncertainty in estimating the anthropogenic climate change. Adjustments of cloud properties to an aerosol perturbation concern among others the cloud fraction, and have been emphasised as particularly complex. Cloud adjustments can generate important responses on the distribution of cloud horizontal sizes. We derive the cloud-size distribution as observational constraint for the cloud-fraction response from high-resolution Landsat satellite data. The goal is to carry out long-term trends in cloud sizes and cloud fraction over Europe during 1985–2018 to investigate the impact of major aerosol reductions during that time. Landsat data with a high spatial resolution of 30m was preprocessed via the web-based platform Google Earth Engine to evade the obstacle of high computational effort and time to handle the comprehensive data archive. The observed multidecadal trends indicate a widespread increase in cloud fraction during 1985–2018. This corresponds to a decrease in the number of small clouds of several 10–100m cloud length, whereas larger clouds (1 km and more), which contribute more to the cloud fraction, became more numerous. We confirm this by showing a largescale decrease of the power-law exponent describing the relative abundance of small and large clouds in the cloud-size distribution. Even though we can interpret the observed changes in cloud properties as significant trends, we do not explicitly identify a clear aerosol signal. Untangling the pure aerosol effect from other confounding factors (e.g., the local meteorology) is therefore left as an outlook for subsequent studies. / Aerosol-Wolken-Wechselwirkungen stellen eine große Unsicherheit in der Quantifizierung des anthropogenen Klimawandels dar. Die sekundären Anpassungen von Wolken an eine Veränderung atmosphärischer Aerosolkonzentrationen betreffen beispielsweise denWolken-Bedeckungsgrad und sind besonders komplex. Wolkenanpassungen können sich in der Veränderung der Wolkengrößen-Verteilung widerspiegeln. Wir präsentieren eine Methode, um mittels Beobachtungen der Wolkengrößen- Verteilung zeitliche Veränderungen in Aerosol-Wolken-Wechselwirkungen nachzuweisen. Wolkengrößen-Verteilung und Wolkenbedeckungsgrad wurden mittels hochauflösender Satellitendaten der Landsat-Serie berechnet. Das Ziel ist es, langjährige Trends im Wolkenbedeckungsgrad über Europa im Zeitraum 1985–2018 herzuleiten und ggf. den Einfluss stark rückläufiger Aerosolkonzentrationen während dieser Zeit zu identifizieren. Landsat-Daten haben eine räumliche Auflösung von bis zu 30 Metern. Um die damit verbundenen großen Datenmengen prozessieren zu können, nutzen wir dieWeb-basierte Plattform Google Earth Engine. Unsere langjährigen Trends zeigen eine großskaligen Zunahme im Wolkenbedeckungsgrad zwischen 1985 und 2018. Dies ist zurückzuführen auf einen relativen Rückgang in der Anzahl kleinerer Wolken (einige 10 bis 100 Meter Länge), während größere Wolken (mehrere Kilometer),welche mehr zum Bedeckungsgrad beitragen, häufiger wurden. Dies zeigt sich im negativen Trend des Power-Law-Exponenten der Wolkengrößen- Verteilung, welcher die relative Anzahl kleiner und großer Wolken beschreibt. Auch wenn sich diese Beobachtungen als signifikante Trends herausstellen, identifizieren wir darin kein klares Aerosol-Signal. Die Isolierung des puren Aerosoleffekts von anderen beeinflussenden Faktoren, wie der lokalen Meteorologie, bietet einen Ansatzpunkt für aufbauende Studien.

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Studded tires are widely used in Nordic areas like Sweden for its good road-gripping performance on icy roads. However, the pavement wear and aerosol caused by studded tires become big concerns considering the usage of studded tires. Studies are carried to quantify the wear and aerosol generated during the process. Among the existing test rigs, most of them which includes a full wheel as specimen have relatively large size. This thesis aims on designing a full wheel testrig with small scale which can fit in a common lab room and be easy to operate. / Dubbdäck används i stor utsträckning i nordiska områden som Sverige för sin goda väggreppande prestanda på isiga vägar. Trottoarslitage och aerosol som orsakas av dubbdäck blir dock stora bekymmer med tanke på användning av dubbdäck. Studier genomförs för att kvantifiera slitage och aerosol som genereras under processen. Bland de befintliga testriggarna har de flesta, som innehåller ett helhjul som prov, en relativt stor storlek. Denna avhandling syftar till att designa en fullhjulstestrigg med liten skala som kan passa i ett gemensamt labbrum och vara lätt att använda.

No / Determining bioequivalence for solution pressurized metered dose inhalers (pMDI) is difficult because the critical characteristics of such products are poorly defined. The aim of this study was to elucidate the non-aerodynamic properties of the emitted aerosol particles from two solution pMDI products that determine their biopharmaceutical differences after deposition. Novel particle capture and analysis techniques were employed to characterize the physicochemical and biopharmaceutical properties of two beclomethasone dipropionate (BDP) products: QVAR and Sanasthmax. The BDP particles emitted from the Sanasthmax inhaler were discernibly different those emitted from QVAR in terms of size (50% larger, less porous), solid state (less crystalline) and dissolution (20-fold slower). When deposited onto the surface of respiratory epithelial cell layers, QVAR delivered ∼50% more BDP across the cell layer in 60 min than Sanasthmax. Biopharmaceutical performance was not attributable to individual particle properties as these were manifold with summative and/or competing effects. The cell culture dissolution− absorption model revealed the net effect of the particle formed on drug disposition and was predictive of human systemic absorption of BDP delivered by the test inhalers. This illustrates the potential of the technique to detect the effect of formulation on the performance of aerosolized particles and contribute to assessment of bioequivalence. / This work was in part funded by a grant from the Safety and Environmental Assurance Centre, Unilever Colworth, U.K. Particle sizing was performed by Steve Ingham, Institute of Pharmaceutical Science, King’s College London.