Dissertationen zum Thema „Aerosol microphysical properties“
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Hamburger, Thomas. „Aerosol microphysical properties during anticyclonic flow conditions over Europe“. Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-127766.
Wurl, Daniela. „Optimal Estimation Retrieval of Aerosol Microphysical Properties in the Lower Stratosphere from SAGE II Satellite Observations“. Thesis, University of Canterbury. Physics and Astronomy, 2007. http://hdl.handle.net/10092/1533.
Wagner, Janet. „Microphysical aerosol properties retrieved from combined lidar and sun photometer measurements“. Master's thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-99830.
Schmidt, Jörg. „Dual-field-of-view Raman lidar measurements of cloud microphysical properties“. Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-150408.
Nichman, Leonid. „Optical measurements of the microphysical properties of aerosol and small cloud particles in the CLOUD project“. Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/optical-measurements-of-the-microphysical-properties-of-aerosol-and-small-cloud-particles-in-the-cloud-project(ad792d0c-90d1-4704-b666-b75d284b40fe).html.
Ditas, Florian. „Microphysical properties of aerosol particles in the trade wind regime and their influence on the number concentration of activated particles in trade wind cumulus clouds“. Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-151594.
Within the scope of this dissertation, microphysical properties of aerosol particles in the trade wind regime and their influence on microphysical properties of trade wind cumulus clouds have been investigated. The study is based on measurements performed with the helicopter-borne measurement platform ACTOS. Two intensive measurement periods were carried out in November 2010 and April 2011, including 31 research flights close to the easternmost Caribbean island - Barbados. Aerosol particle number size distributions show a bimodal structure, which is typical for marine aerosol particles. The total particle concentrations of approximately 100-1000 cm-3 are compared to continental conditions relatively low. A statistical analysis of individual clouds reveals typical number concentrations of activated particles up to 400 cm-3 and minimum activation diameters between 40 and 180 nm with corresponding critical supersaturations between 0.1 and 1%. Additionally, major factors affecting the number concentration of activated particles are identifed: 1) vertical wind velocity at cloud base and, 2) number concentration of available aerosol particles as potential cloud condensation nuclei. With the help of observational data and a comprehensive sensitivity study using a spectral cloud microphysical parcel model, the sensitivity of the cloud droplet number concentration towards changes in the microphysical aerosol particle properties and their hygroscopicity has been investigated. Observational results in terms of so-called aerosol-cloud interactions metrics (describes a measure of the influence of changes in one specific aerosol property on one specific cloud property) show a very high sensitivity (close to the physical meaningful maximum of unity) of the number concentration of activated particles towards changes in the particle number concentration. These aerosol-cloud interaction metrics can be used as basis for observationally-based radiative forcing estimates. Additional model calculations cover the entire range of the observed aerosol properties during both campaigns. The results underline particularly the importance of the physical aerosol properties. The calculated susceptibility (valuation: 0-1) of the droplet number concentration towards changes in the particle number concentration is highest (> 0.9) for accumulation mode dominated particle number size distributions and decreases for Aitken mode dominated size distributions (> 0.6). In contrast, for the modeled parameter space, the sensitivity towards changes in the particle hygroscopicity is generally below 0.4. The findings presented in this study represent a comprehensive characterization of aerosol and cloud microphysical properties in the trade wind regime. These findings may help to evaluate the predicted sensitivity of cloud microphysical properties by climate models towards changes in particle microphysical properties and reduce the uncertainties in climate sensitivity estimates
Schmidt, Jörg [Verfasser], Andreas [Akademischer Betreuer] Macke, Andreas [Gutachter] Macke und Herman [Gutachter] Russchenberg. „Dual-field-of-view Raman lidar measurements of cloud microphysical properties : Investigation of aerosol-cloud interactions / Jörg Schmidt ; Gutachter: Andreas Macke, Herman Russchenberg ; Betreuer: Andreas Macke“. Leipzig : Universitätsbibliothek Leipzig, 2014. http://d-nb.info/123878867X/34.
Ditas, Florian [Verfasser], Alfred [Gutachter] Wiedensohler und Alfons [Gutachter] Schwarzenböck. „Microphysical properties of aerosol particles in the trade wind regime and their influence on the number concentration of activated particles in trade wind cumulus clouds / Florian Ditas ; Gutachter: Alfred Wiedensohler, Alfons Schwarzenböck“. Leipzig : Universitätsbibliothek Leipzig, 2014. http://d-nb.info/1238789293/34.
Chang, Yuyang. „Développement d'un nouvelle technique de mesure du profil atmosphérique en aérosols à l'aide d'un lidar Raman-dépolarisation-fluorescence“. Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2023/2023ULILR060.pdf.
Vertical information on aerosol optical and microphysical properties is of significant importance to study aerosol evolution, transport, as well as their impacts on human health, local environment and global climate. This thesis developed an algorithm, the Basic algOrithm for REtrieval of Aerosol with Lidar (BOREAL), for retrieving heigh-resolved aerosol microphysical properties from combinations of extinction, backscattering and depolarization lidar measurements. Based on maximum likelihood estimation, the retrieval algorithm uses a nonlinear iteration approach to search for the best fit to both measurements and constraints. The retrieved aerosol microphysical properties include particle size distribution, volume concentration, effective radius, complex refractive index (CRI) and single scattering albedo (SSA).The performance of BOREAL, retrieval accuracy and measurement sensitivity are assessed through simulated data. In general, retrieval accuracy is higher for fine-mode particles than coarse-mode particles. The simulations demonstrate the importance of exploiting a priori constraint to improve the retrieval accuracy of CRI and SSA. Apart from spherical particles, performance of retrieving non-spherical particles is also evaluated by integrating three different particle scattering models, i.e., the Sphere, Spheroid and Irregular-Hexahedral (IH) models, into BOREAL. The results show incorporating depolarization measurements into inversion is essential to better constrain and stabilize the retrieval. Besides, approximating non-spherical particles to spheres will evidently degrade retrieval quality in cases of lidar measurements. In addition, BOREAL is applied to real lidar observations of different aerosol types, including biomass burning, dust and continental polluted aerosols at the ATOLL observatory. Results are analyzed and compared with retrievals from AERONET and previous studies, which demonstrates the robustness of BOREAL for real data application and aerosol characterization.Overall, this work contributes to Labex CaPPA and ACTRIS efforts to better quantify aerosol microphysical properties using lidar measurements
Ridley, David A. „Aerosol Radiative Properties Analysed using Global Models of Aerosol Microphysics“. Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494262.
Karol, Yana. „Determination of optical and microphysical properties of atmospheric aerosols from multi-wavelength airborne sun photometer“. Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10137/document.
Atmospheric aerosols still represents one of the greatest uncertainty in the study of the processes of climate change. The diversity of aerosol sources and their formation mechanisms make the spatial distribution of aerosols very inhomogenous and requires numerous instruments and different approaches for their analysis. A new multi-wavelength airborne sun photometer PLASMA (Photomètre Léger Aéroporté pour la Surveillance des Masses d’Air) developed in the Laboratory of Atmospheric Optics allows providing on-board measurements of aerosol optical depth over a wide (0.34 − 2.25 μm) spectral range and at different altitudes. The information of vertical distribution of aerosol optical properties can be then used to validate the lidar processing algorithms. It is possible to retrieve from PLASMA measurements the size distribution of the aerosol particles at different levels. Also, the instrument can be installed on an automobile in order to measure the horizontal profiles of AOT. This study is dedicated to characterization and calibration of PLASMA and to the analysis of several data sets. Numerous ground-based, airborne and automobile measurements were held and compared with other instruments. Sensitivity study of the Dubovik’s inversion algorithm showed that it is possible to get the particle’s size distribution from only AOD measurements assuming a value of the refractive index within a limited domain. Airborne PLASMA measurements were inverted and size distributions of the aerosol particles were obtained at different altitudes. This new information is helpful to better understand the formation and spatial distribution of aerosols in the atmosphere
Karol, Yana. „Determination of optical and microphysical properties of atmospheric aerosols from multi-wavelength airborne sun photometer“. Electronic Thesis or Diss., Lille 1, 2013. http://www.theses.fr/2013LIL10137.
Atmospheric aerosols still represents one of the greatest uncertainty in the study of the processes of climate change. The diversity of aerosol sources and their formation mechanisms make the spatial distribution of aerosols very inhomogenous and requires numerous instruments and different approaches for their analysis. A new multi-wavelength airborne sun photometer PLASMA (Photomètre Léger Aéroporté pour la Surveillance des Masses d’Air) developed in the Laboratory of Atmospheric Optics allows providing on-board measurements of aerosol optical depth over a wide (0.34 − 2.25 μm) spectral range and at different altitudes. The information of vertical distribution of aerosol optical properties can be then used to validate the lidar processing algorithms. It is possible to retrieve from PLASMA measurements the size distribution of the aerosol particles at different levels. Also, the instrument can be installed on an automobile in order to measure the horizontal profiles of AOT. This study is dedicated to characterization and calibration of PLASMA and to the analysis of several data sets. Numerous ground-based, airborne and automobile measurements were held and compared with other instruments. Sensitivity study of the Dubovik’s inversion algorithm showed that it is possible to get the particle’s size distribution from only AOD measurements assuming a value of the refractive index within a limited domain. Airborne PLASMA measurements were inverted and size distributions of the aerosol particles were obtained at different altitudes. This new information is helpful to better understand the formation and spatial distribution of aerosols in the atmosphere
Morales, Betancourt Ricardo. „On the representation of sub-grid scale phenomena and its impact on clouds properties and climate“. Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50373.
Gasteiger, Josef Konrad. „Retrieval of microphysical properties of desert dust and volcanic ash aerosols from ground-based remote sensing“. Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-137867.
Targino, Admir Créso. „Regional studies of the optical, chemical and microphysical properties of atmospheric aerosols : Radiative impacts and cloud formation“. Doctoral thesis, Stockholm University, Department of Meteorology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-740.
Atmospheric particles are ubiquitous in the Earth’s atmosphere and have potential to influence atmospheric chemistry, visibility, global climate and human health, particularly downwind from major pollution sources. The main objective of this thesis was to investigate questions pertaining to the microphysical, chemical and optical properties of aerosol particles by using in situ data collected during four experiments carried out in different regions of the Northern Hemisphere.
The first two papers of this thesis reports on airborne measurements of the aerosol optical properties performed over the North Atlantic and the Los Angeles basin. Airmasses from Europe and North Africa are usually advected in over the North Atlantic, alternating with the background marine conditions. The results showed that the aerosols are not uniformly distributed in the area and variability in the aerosol fields occurs at sub-synoptic scales. It was also observed that the single scattering coefficient varied as the polluted plumes aged, suggesting a relationship between this quantity and transport time. The measurements performed around the Los Angeles basin showed that the area’s complex topography and local meteorological circulations exert a strong control on the distribution of the aerosol in the basin. Large spatio-temporal gradients in the aerosol optical properties were observed along a transect flown from the shore towards the mountains. Profiles flown over sites located on the mountains displayed a stratified configuration with elevated aerosol layers.
Airborne data of residual particles collected in orographic wave clouds over Scandinavia were analyzed using a single particle analysis technique. Mineral dust, organic aerosols and sea salt were the main group of particles identified. Residuals composed predominantly of mineral dust were found in glaciated clouds while organic residuals were found in liquid clouds. The results suggest that organic material may inhibit freezing and have considerable influence on supercooled clouds that form through heterogeneous pathways.
The partitioning of the aerosol particles between cloud droplets and interstitial air has been addressed in terms of their microphysical properties using data obtained at a mountain-top site in Sweden during a stratocumulus event. The results showed that the scavenging efficiency varied during the cloud event, and Aitken-mode particles were also efficiently scavenged in addition to accumulation-mode particles. It is hypothesized that alterations of the aerosol chemical composition occurred during the measurement period, modifying the hygroscopic nature of the particles and decreasing their activation diameter.
Targino, Admir Creso. „Regional studies of the optical, chemical and microphysical properties of atmospheric aerosols : radiative impacts and cloud formation /“. Stockholm : Dept. of meteorology, Stockholm university, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-740.
Chen, Wei-Ting Wennberg Paul O. Seinfeld John H. „I. Global simulations of interactions between aerosols and future climate and ; II. Sensitivity of multiangle imaging to the optical and microphysical properties of biomass burning aerosols /“. Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-12182008-174607.
Lafrique, Pierre. „Lidar multispectral pour la caractérisation des aérosols“. Thesis, Toulouse, ISAE, 2015. http://www.theses.fr/2015ESAE0033/document.
The purpose of this thesis is to show the contribution of a multispectral Iidar for the characterisation of aerosols, in particular hen wavelengths in near infrared are added. Indeed, compared with a mono-wavelength Iidar, the information contained in multispectral profiles allow to retrieve the microphysical properties of aerosols (particule size distribution and composition). To this end, we adapted a multispectral Iidar signal simulator to our study in order to develop and test two methods which objective is to obtain the microphysical properties of aerosol along the line-of-sight from synthetic lidar signals. The first method, based on the inversion of lidar signals, enables to find the length distribution of aerosols and therefore to educe their concentration and their modal radius. This method requires a priori information about the aerosols. An error budget was made by introducing uncertainties on the a priori parameters. It shows that the results obtained regarding the concentration and modal radius are accurate (respectively 16% and 17% uncertainty). The advantage of this method is that it does not require absolute calibration of the instrument. The principle of the second method is to minimize the difference between the studied and the simulated signals. Even if the accuracy on the size distribution is lower (35% and 40% on the concentration and modal radius) and the calibration constant of the instrument has to be known, this method has the advantage to find the concentration of the aerosols in 74% of the cases. Finally, the first method was validated on real data, coming from a collaboration with the RSLab (Barcelona), by comparing ur results with those obtained by this team (7% difference on the modal radius)
Gasteiger, Josef Konrad [Verfasser], und Bernhard [Akademischer Betreuer] Mayer. „Retrieval of microphysical properties of desert dust and volcanic ash aerosols from ground-based remote sensing / Josef Konrad Gasteiger. Betreuer: Bernhard Mayer“. München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2011. http://d-nb.info/1018847170/34.
Korgo, Bruno. „Caractérisation optique et microphysique des aérosols atmosphériques en zone urbaine ouest africaine : application aux calculs du forçage radiatif à Ouagadougou“. Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22509/document.
In this thesis, we analyze the main characteristics of atmospheric aerosols on an urban site in West Africa: Ouagadougou. This analysis is followed by an assessment of the radiative forcing produced by this population of aerosols at the top of the atmosphere, in the atmospheric layer and at the Earth's surface. A climatological study of the optical properties (optical thickness, Angstrom exponent, single scattering albedo, asymmetry factor) and microphysical properties (particle size distribution, complex refractive index) was performed on basis of data obtained from photometric measurement and inversions of AERONET network. The analysis of these data allowed us to define the different variabilities of the properties studied at various time scales. These properties have highlighted the combined effects of human activity, the cycle production of mineral dust from the Sahara region, the seasonal succession and the climate dynamics known in this region of the earth. The composition of the aerosol plume was also deduced from the analysis of optical data, and the conclusions were found to be in good agreement with chemical analysis carried out at LSCE on samples obtained by sampling on filters at Ouagadougou. The radiation balance was assessed using the GAME model. This simulation showed a strong relationship of the radiative forcing with the succesion of wet and dry seasons, with extreme values in August (wet) and Mars (dry with maximum dust emissions). The results showed a cooling at the surface that can reach -41 W / m 2 in March, a warming of the atmosphere, ranging from 15 to 35 W / m 2 about and a cooling at the top of the atmosphere between -2 and -6 W / m 2 . The representation of the radiative forcing calculated as a function of the single scattering albedo showed a linear trend with a correlation coefficient reflecting relatively good reliability of our results (about 88%). The consistency of simulated values was also shown by a comparison with the results obtained in the West African region by other researchers using different techniques. Similarly, the representation of the radiative efficiency simulated as a function of the inverted AERONET one showed a very good agreement
Hamburger, Thomas [Verfasser]. „Aerosol microphysical properties during anticyclonic flow conditions over Europe / vorgelegt von Thomas Hamburger“. 2010. http://d-nb.info/1011054582/34.
Lee, Keun-Hee. „Modeling the Direct and Indirect Effects of Atmospheric Aerosols on Tropical Cyclones“. Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10390.
Chen, Wei-Ting. „I. Global Simulations of Interactions between Aerosols and Future Climate and II. Sensitivity of Multiangle Imaging to the Optical and Microphysical Properties of Biomass Burning Aerosols“. Thesis, 2009. https://thesis.library.caltech.edu/5060/1/Thesis_2side.pdf.