@phdthesis{Koch2003, author = {Koch, Bernhard}, title = {Atmospheric traces monitoring using cavity ringdown spectroscopy}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-000000363}, school = {BTU Cottbus - Senftenberg}, year = {2003}, abstract = {Cavity Ringdown laser Spectroscopy has been applied to develop a novel in-situ monitoring device for atmospheric trace gases. The study has been dedicated to the detection of NO2 and HONO compounds which play an important role in atmospheric chemistry. The system, based on a Nd-YAG pumped UV-VIS OPO laser, has performed field experiments under harsh conditions showing high reliability and a detection limit in the 500 ppt range. Longer term measurements performed from the laboratory of the institute for air chemistry (BTU Cottbus) in Berlin-Adlershof in autumn and winter 2001/2002 showed very good coincidence with the results of the Berliner Luftg{\"u}te Meßnetz (BLUME). Present limitations in the performance have been elucidated putting in to evidence the effect of the aerosol content of the atmosphere. On the other hand, the possibility of quantitative aerosol analysis could be demonstrated.}, subject = {Atmosph{\"a}re; Spurengas; Stickstoffoxide; Cavity-Ring-Down-Spektroskopie; In situ; Cavity ringdown spectroscopy; CROS; Optical parametric oscillator; OPO; Nitrogen dioxide}, language = {en} } @phdthesis{Sehili2005, author = {Sehili, Aissa Mounir}, title = {Coupling between complex multiphase chemistry and detailed microphysics in a size resolved cloud model}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-000000938}, school = {BTU Cottbus - Senftenberg}, year = {2005}, abstract = {The target of the present work was to develop, implement and test a coupling strategy between a complex multiphase chemistry and a size resolved microphysics in order to accurately simulate the multiphase processes taking place in a cloud. The coupling scheme provides time-interpolated meteorological variables and time-averaged mass fluxes over a defined coupling time interval for chemistry. The resulting ODEs are large, non-linear and extremely stiff. Implicit time integration schemes based on the BDF and on the second order Rosenbrock methods associated with direct sparse solvers were used to solve the resulting systems. The coupled model SPACCIM (Spectral Aerosol Cloud Chemistry Model) was evaluated for various case studies. Comparison with measured values from a field experiment showed a good agreement and proofed that the coupling strategy is robust and reliable. Moreover, the model is capable to handle different microphysical approaches and to deal with different reacting mechanisms under various types of dynamics with high flexibility.}, subject = {Atmosph{\"a}re / Chemie; Atmosph{\"a}re; Physik}, language = {en} } @phdthesis{Rusumdar2013, author = {Rusumdar, Ahahmad Jhony}, title = {Treatment of non-ideality in the multiphase model SPACCIM and investigation of its influence on tropospheric aqueous phase chemistry}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-28190}, school = {BTU Cottbus - Senftenberg}, year = {2013}, abstract = {The troposphere is a complex multiphase and multicomponent environment with simultaneously occurring gas and aqueous phase as well as heterogeneous chemical transformations, which can potentially alter the physico-chemical composition of aerosols. In this multicomponent system, phase transfer processes take place, which can influence the particle and droplet formation as well as particle growth. In the modeling of such multiphase processes it is necessary to consider non-ideal conditions in deliquescent particles. Such, highly concentrated solutions are typical when small amounts of water available in aqueous aerosol particles. The behavior of this non-ideal mixed solvent-electrolyte solutions including inorganic and organic chemistry is not yet described satisfyingly in existing multiphase models. In light of this, a modeling framework has been developed in the context of multiphase air parcel model to treat the kinetic description of phase transfer processes considering complex multiphase chemistry and an extended description of non-ideal solutions for the aqueous phase chemistry by means of activity coefficient models. Activity coefficient models, such as AIOMFAC, mod. LIFAC and Pitzer-ion interaction models were implemented in this work. The current available activity coefficient models developed for electrolyte-organic-water mixtures are evaluated in the first part of the thesis. For that, the model investigations cover a scale, ranging from very simple to complex simulations. The implemented module can use different combinations of mixing rules and activity coefficient models flexibly. In the second part of the thesis, the extended activity coefficient model was implemented in the parcel model framework SPACCIM, in order to investigate the influence of treatment of non-ideality on multiphase chemistry. The effect of considering non-ideal solutions was studied for two different aerosol types (remote, urban) regarding complex multiphase chemistry. The advanced model simulations have shown under which circumstances it is important to consider non-ideal solutions and how they will affect the simulated particle/droplet growth and chemical transformations. The modeled activity coefficients and their pattern, which decides the multiphase chemical transformations, were investigated for inorganic and organic systems. The present results have shown that, the inclusion of the treatment of non-ideality can substantially extend our ability to model complex multiphase chemistry especially in the particle phase.}, subject = {Wolke; Aerosol; Phasenumwandlung; Modellierung; Multiphasenmodellierung; Aerosol-Wolken-Wechselwirkung; Phasentransfer; Nicht-ideale L{\"o}sungen; Aktivit{\"a}tskoeffizienten; Multiphase modeling; Aerosol-cloud-interactions; Phase transfer; Non-ideal solutions; Activity coefficients}, language = {en} }