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

Architektur vernetzter Systeme - Seminar im WS 1999/2000

Available from TIB Hannover: RA 2045(2000,10) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

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

Modellierung und Parametrisierung chemischer Reaktionen im Zusammenhang mit Nebelereignissen (EUMAC). T. 2 Abschlussbericht

The concentration and time dependent composition of aerosol particles in the atmosphere has an effect on the formation of cloud and fog droplets and on the liquid phase chemistry in clouds and fog. Furthermore, the presence trace gases has an influence on liquid phase chemistry. Due to photochemical reactions during the day, there is a large difference between daylight and nocturnal chemistry. To improve the description of chemical reactions in the liquid phase in numerical models, the following model developments were carried out: a) Photolysis frequencies inside of droplets containing absorbing aerosol material are modelled additionally to the photolysis in the gas phase. Compared to the gas phase, the actinic flux in the droplets is enhanced by a factor of about two. Regarding the radical source strengths the photolysis of the iron(III)-hydroxy-complex is the most efficient of the OH-forming photochemical reactions in the liquid phase. b) To improve the efficient description of cloud physics and chemistry a model was developed where two modes instead of a simple bulk description are modelled to describe the liquid phase. The model results shown in agreement with explicit microphysics calculations that the main mass of sulfate was formed on the smaller droplets of the first dorplet class which holds also the main water mass. Due to the higher deposition velocity of the large droplets, the second droplet class contributes significantly to the moist deposition. (orig.)SIGLEAvailable from TIB Hannover: F96B2002+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

SOAF- Design and Implementation of a Service enriched Social Network

Abstract. In this paper, we propose the integration of services into social networks (SOAF- Service of a Friend) to leverage the creation of the Internet of Services vision. We show how to integrate services and humans into a common network structure and discuss design and implementation issues. In particular, we discuss the required extensions to existing social network vocabulary with regard to services. We illustrate a scenario where this network structures can be applied in the context of service discovery and highlight the benefit of a service-enriched social network structure.