Simulation of the ozone formation in the northern part of the Po Valley

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95424/1/jgrd8866.pd

Modellierung photolytischer Prozesse in der Troposphaere

Zur Modellierung der Photochemie ist die Kenntnis der verschiedenen Reaktionsgeschwindigkeiten und aller Groessen auf < #+-# 10% notwendig, um Aussagen ueber die Wirkung einzelner Prozesse treffen zu koennen. Diese hohe Genauigkeit lieferten die bisherigen Photolysemodelle nicht. Mit dem im Rahmen dieser Dissertation entwickelten Modell STAR (System for Transfer of Atmospheric Radiation) ist es dagegen moeglich in allen Hoehen der Troposphaere die Strahlungsflussdichte (durch eine horizontale Flaeche), den aktinischen Fluss (Strahlungsflussdichte durch die Oberflaeche eines Volumen), die gerichtete Strahldichte und die Photolysefrequenzen fuer 21 photochemisch relevante Gase mit der benoetigten Genauigkeit numerisch effizient zu berechnen. Mit STAR wurden Sensitivitaetsstudien erstellt, um die einzelnen Einflussgroessen und physikalischen Prozesse bewerten zu koennen und den Fehler, der durch Vernachlaessigung eines Prozesses entsteht, bestimmen zu koennen. (orig./MM)The modelling of photochemistry requires knowledge of the different reaction speeds and all parameters up to < #+-# 10% in order to permit statements on the effectiveness of individual processes. Such high accuracy was not to be attained by current photolysis models. By contrast, the use of the model STAR (System for Transfer of Atmospheric Radiation), developed within the framework of this thesis, permits numerically efficient calculation of the radiation flux density (through a horizontal plane), the actinic flux (radiation flux density through the surface of a volume), the directional radial intensity per unit area, and the photolysis frequencies for 21 photochemically relevant gases at all altitudes of the troposphere.- STAR has been used to conduct sensitivity studies with a view to evaluating the individual factors of influence and physical processes and in order to determine the error arising from the neglect of a process. (orig.)SIGLEAvailable from TIB Hannover: ZA 5031(68) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Fog chemistry during EUMAC joint cases. Analysis of routine measurements in southern Germany and model calculations

The role of fog events for acid production and moist deposition in southern Germany during three EUMAC Joint Cases has been investigated by analysis of routine measurements and simulations with a one-dimensional fog-chemistry model. To identify the chemical and meteorological conditions, routine measurements by different institutions have been interpreted. The periods under consideration include a smog episode with low photooxidant concentrations during the 'Winter Case' in February 1982. The 'Wet Case' in spring 1986 represents a period with higher photooxidant concentrations. Conditions which are mostly characterized by low SO2 and oxidant concentrations and comparatively high pH-values in the fog are given during the 'SANA 1' case in autumn 1990. Fog mostly occurs as a subscale phenomenon, but sometimes it can also cover large areas and it can contribute significantly to moist deposition. The model results indicate that the liquid phase sulfate production in the fog layer may even e xceed the gas phase production during 24 hours within a layer of the same height occasionally. On the other hand, during the SANA 1 case the sulfate production in the fog was extremely low at night due to lack of oxidants and SO2. Depending on the dissipation time of the fog a remarkable effect on the photolysis rates is possible. Since a significant amount of particulate mass is lost by moist deposition during fog, it is evident that fog events can have a noticeable effect on some of the gas phase constituents which are easily soluble

Using Embedded Sensor Networks to Monitor, Control, and Reduce CSO Events: A Pilot Study

sensor network

Relevance of Photolysis Frequencies Calculation Aspects to the Ozone Concentration Simulation

For the simulation of photochemically created pollutants like ozone it is essential to correctly consider reaction rates induced by short-wave radiation. In atmospheric chemistry transport models this is achieved by the use of either off- or online calculated photolysis frequencies. In this study the effect of different input parameters of a radiation model on the calculated photolysis frequencies have been investigated. In the second step an atmospheric chemistry transport model was used to assess the impact of changed photolysis frequencies on the simulation of ozone concentrations. The impact of changed radiation model input parameters on the calculated photolysis frequencies vary not only with regard to the changed parameter but also with regard to the to the species to be dissociated. Furthermore the impact of different sets of photolysis rates employed in a chemical transport simulation on the modelled concentrations is differed and likely to be less important than other aspects of the simulation like the resolution of the grid and the emissions used. Apart from major surface albedo changes (grass to snow) and extreme changes in total ozone column content for JO3 clouds are the dominating factor in modifying the photolysis frequencies especially as they feature a highly temporal and special variation. The results show that simulated maximum ozone concentrations in areas with clouds are reduced

Modellierung und Parametrisierung chemischer Reaktionen im Zusammenhang mit Nebelereignissen (EUMAC) Abschlussbericht

Includes 3 3,5' discsAvailable from TIB Hannover: RR 8418(94-S1)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman