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1	The suitability of optical particle counters for covariance estimates of the dry deposition velocity of particulate aerosols Hubbe, John McBain 12 June 1984 (has links) Experimental work at the 1982 Dry Deposition Intercomparison Experiment (DDIEx) involved the use of optical particle counters for covariance estimates of dry deposition velocities of accumulation mode aerosols. Meteorological and particle flux observations are presented. Deposition velocity estimates exhibit scatter about zero. A formulation of the standard error of the deposition velocity estimator is derived and examined. Using this formulation, the observed deposition velocities are shown to be marginally significant. Using a case study, the correlation coefficient is examined and presented as an important statistic to the work. Humidity effects on the measurements are briefly examined. Recommendations are made for improvements in the instrumentation. / Graduation date: 1985 Optical particle counters Dry deposition velocity Particulate aerosols
2	Inverse Atmospheric Dispersion Modeling in Complex Geometries / Invers atmosfärisk spridningsmodellering i komplexa geometrier Pelland, Charlie January 2022 (has links) In the event of a radioactive release in an urban environment the consequent response mustbe swift and precise. As soon as first responders have correct information, they can make anaccurate risk assessment. However, if the position, release rate and time of the radioactiverelease is unknown it is hard to know how the pollutant will spread. This thesis aims to testa model which approximates these three unknowns using weather data (wind and rain) as wellas measurement data collected at sensors placed around an urban environment. An atmospheric dispersion model based on an existing Reynolds Averaged Navier-Stokes modelis set up in two geometries of different complexity to create forward mode synthetic depositiondata and adjoint mode concentration fields resulting from a fixed dry deposition velocity andscavenging effect for wet deposition. Variations of time- and space-dependent rainfall is simu-lated. The resulting data is used in an existing optimization model, where a parameter studyis conducted regarding regularization coefficients. This thesis shows that the optimization model accurately estimates position and its approximaterelease rate of a 2D geometry of radioactive releases using a logarithmic optimization approach,and fail to do so using a linear optimization approach. The logarithmic optimization model alsoapproximately estimates position and release rate in a 3D geometry. Regularization parametersshould be within the range of 0.1 and 1.2 depending on rain. More rain requires smallerparameters and will estimate a lower release rate. Time-dependent rainfall is shown to have amajor negative effect on simulation time.iii atmospheric dispersion modeling dispersion modeling invers dispersion modeling atmospheric dispersion invers atmospheric dispersion CFD computational fluid dynamics radioactive release openfoam CRBN dry deposition dry deposition velocity scavenging effect wet deposition optimization model Reynolds Averaged Navier-Stokes adjoint mode time-dependent rain simulation time-dependent rain time dependent rain simulation time dependent rain Meteorology and Atmospheric Sciences Meteorologi och atmosfärforskning Fluid Mechanics and Acoustics Strömningsmekanik och akustik

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The suitability of optical particle counters for covariance estimates of the dry deposition velocity of particulate aerosols

Inverse Atmospheric Dispersion Modeling in Complex Geometries / Invers atmosfärisk spridningsmodellering i komplexa geometrier