Sascha Henninger

A Mobile Measuring Methodology to Determine Near Surface Carbon Dioxide within Urban Areas

Atmospheric carbon dioxide is one of the infra-red active trace gases responsible for the anthropogenic global warming. Due to the increasing use of fossil fuels within the lower atmosphere, but also within the urban boundary layer of urban agglomerations, an increase of the CO2 concentration must be expected. Less is known about the temporal and spatial behavior of this trace gas, especially in cities and their surrounding areas. Between 2002 and 2004 first investigations were made about the distribution of the CO2 concentration within the urban canopy layer of the city of Essen, Germany (51°28`N, 7°0`E). These first measurements should develop and verify a mobile measuring methodology to determine the air quality indicators, first of all CO2, but also CO, NO, SO2, O3, in dependence of the urban types of land use, the topographical circumstances and the meteorological conditions and how to transfer this methodology to other cities. For this implementation there were additional mobile measurements done in different cities within different climatic zones from 2006 till 2010. The structure of emission within an urban area is mainly characterized by traffic and the private domestic heating (especially in winter). The proportion of power plant and industrial facilities is less, because of the plume height of the stacks. Most of this emission is blown away from the urban sites. On the basis of the predominantly low source heights and the invariable and variable factors, which determine the distribution of the trace substances and define their chemical transformation, the question was how the emission is dependent on the local urban types of land use and how these were affiliated with each other. Because of the different sources of emission the urban air quality is spatially as well as temporarily extremely volatile. Some reasons for this inhomogeneous field of emission are the transportation infrastructure, different heights of the emission sources and the limited exchange of the urban canopy layer within the street canyons. Therefore, it is hardly possible to use results of air quality measurements from fixed urban measuring stations. An adequate transferability of these could not be guaranteed for more than the immediate proximity of the station. One way of analyzing the fine structure of the different fields of emission is creating a numerical analysis model which enables a prediction of the trafficrelated exposure. However, this modeling requires a corresponding number of input values and a suitable validation.

Notwendiger Wandel im Umgang mit innerstädtischen Grünflächen

Der Erholungswert innerstadtischer Grunflachen ist unumstritten und auch die positive lokalklimatische Wirkung auf die nahere Umgebung urbaner Parkanlagen ist in Abhangigkeit der Groβe und Gestaltung hinlanglich bekannt. Dennoch besteht in Bezug auf die Betrachtung der lufthygienischen Verhaltnisse ein gewisser Nachholbedarf. Es gilt zu beachten, dass einige Baumarten unterschiedliche Mengen an biogenen Kohlenwasserstoffen emittieren.

Applied and Planning-Oriented Urban Climatology at the University of Kaiserslautern

Urban authorities and stakeholders demand for answers on climatological and air quality related problems in the urban area. Applied and planning-oriented urban climatology provides the link between climatology and urban planning. Therefore, one aim of the Department of Physical Geography, Faculty of Regional and Environmental Planning, University of Kaiserslautern, Germany, is to understand how newly gained free space in shrinking cities can be integrated useful—in terms of urban climatology—in new utilization structures. For example, how can fresh and cold air production zones be incorporated in urban planning? Furthermore, the potential of the hardly noticed green roofs in order to enhance the urban micro climate is investigated, especially in arid and semi-arid zones. In addition, a database of roadside greenery and canopy is developed to characterize the influences on urban air quality. Parameters that are taken into account are amongst others canopy density and emission of volatile organic compounds. A dense canopy can reduce air movement leading to the accumulation of air pollution like within an urban canyon. Several tree species emit volatile organic compounds that contribute as a precursor to the formation of ground level ozone and are therefore not suitable for planting as urban green. Through the applied and planning-oriented urban climatology we provide recommendations of action for urban authorities.

The Impact of Biogenic Isoprene in Dependence on Meteorological Conditions within Urban Green

It is indisputable that urban green spaces have a positive impact on their nearby vicinity, but also for the residents. Though it does not matter, if it is a positive effect on the local climate or for recreational values. Nevertheless, an awkward planting could lead to an accumulation of air pollutants. From the applied urban climatology’s point of view it is necessary to think about planning new vegetation within urban parks. In comparison to a climatic adjusted construction all over the urban area, likewise for new plantings throughout the planning phase the predominantly planted species must be considered in the right way. The analysis of the air pollution situation within different urban park areas in Kaiserslautern, Germany, inevitably revealed that during clear and calm weather conditions biogenic precursors could be emitted by diverse plants. Less atmospheric exchange, high air temperature and solar radiation arrange it so that near surface ozone is formed. Due to the fact that this air quality indicator could be diluted or dispatched the accumulation of it leads to higher concentration. It could be calculated that a wrong proportion of species which emit higher rates of biogenic hydrocarbons and the size of the green area lead to a location-based formation of near surface ozone by e. g. biogenic isoprene. Finally, this ends in a negative assessment of the recreational value of such an area in relation to the benefits which an urban green area should rather have. However, it is possible to react on this. Planning oriented recommendations for action could be given for optimizing the air quality situation. Ultimately, it is frequently only the lack of knowledge that diverse species of the current vegetation stock of an urban green area lead verifiably to an increase of the local near surface ozone concentration.