Due to their close substantive interrelationship, there are common explanatory texts for the Maps 04.10.01 through 04.10.12 in the chapters Overview, Data Base and Methodology. In the chapter Map Description, a breakdown by map is provided as follows, with individual evaluations for:
- Near-ground temperatures (10 PM)
- Near-ground temperatures (6 AM)
- Air exchange and air-mass currents (10 PM and 6 AM) in the entire area;
The results obtained in the context of the previous climate investigations for the Berlin Environmental Atlas, as documented in Maps 04.02 through 04.07 and 04.09 (SenStadt 2001a-e and SenSUT 1998),have essentially been based methodologically on the execution of a stationary and mobile measurements, as well as the interpretation of basic information, such as regional planning or sealing data. These methods have, however permitted the investigation and delimitation of local and regional wind- circulation systems, which are of unquestioned fundamental significance for the urban climate of a metropolitan area, especially in a largely flat region.
A modern climatic analysis designed for practice must particularly encompass the process system of air-exchange flows, and attempt to make a connection between these processes and the structuring of the area under investigation into spaces which are favorable and unfavorable, respectively, in terms of urban climate and air-quality. These two terms describe, from a climatic viewpoint, the structure of an area into compensation spaces, affected spaces and connecting structures (air-stream channels), and an understanding of such an area as a construct consisting of compensation and stress areas. “A compensation space is thus an undeveloped space characterized by vegetation, which by generating cool and fresh air, can reduce or eliminate air-quality or bio-climatic burdens in an affected space via functional exchange interaction. An impact area is a space which is burdened, built-up or planned for construction, and which is connected to an adjacent compensation space via air exchange processes, or to a non-adjacent compensation space via a ventilation lane” (cf. Mosimann, Frey, Trute and Wickenkamp 1999). This procedure thus breaks fundamentally with the previously common static view based on urban climate zones, which subdivided the area of investigation into spatial units in which the micro-climatically most important factors were relatively homogeneous and the effects hardly differed (cf. VDI 1997).
Accordingly, a uniform digital climatic model designed to make the investigation of these aspects possible in a high spatial resolution has been applied for the first time 2003/2004 (SenStadt 2003 und SenStadt 2004b) in the context of a project for the entire urban area of Berlin. A central component of this procedure is the FITNAH procedural package (cf. Methodology chapter). This approach incorporates the following important advantages:
- The comparability of results in the overall area is ensured;
- In addition to the qualitative statements designed to characterize particular urban climatic phenomena, quantitative statements concerning climate-ecological conditions and exchange processes are also possible;
- Climate-ecological compensation and process spaces are localized in the urban area and represented in their spatial dimensions as precisely as possible;
- An important aspect of the climate-ecological compensation potential of open areas – the cold-air balance – has been investigated on a comprehensive city-wide basis for the first time in Berlin.
- FITNAH provides also the extensive calculation of the dispersion of air pollutants within the assumed meteorological conditions.
This investigation, too, supports the repeatedly confirmed connection between the climate of various urban areas and their structure in terms of buildings, open areas and vegetation. However, the typical local climate is not only generated by the structure of an urban area but also by its situation within the city. Hence, different areas of a city can interact mutually, or with the surrounding countryside. The temperature differences between neighboring areas are of decisive importance for the climatic exchange. A reduction of these differences, e.g. due to an increase in the structural density, or the uniformization of structures, will cause the urban climate to deteriorate. More detailed information on these topics, and on the effects of overall weather situation on the local climate are found in the explanatory text for Map 04.07 Climate Functions (SenStadt 2001e).
The purpose of the present updated Maps 04.10.01 – 04.10.12 is to present the results of the application of the regional simulation model FITNAH. In order to achieve comparability with the climate parameters already published in the Digital Environmental Atlas, the distribution of air temperature during two time segments is also presented, although a direct comparison of the map representations based on measurements and analogical conclusions with the results of simulations of model applications requires that the differing frameworks be taken into account. This advice has also be considered when comparing the results of the both FITNAH model applications of the 2003/2004 edition and 2009. As on the one hand scope and level of detail of the input data, and, on the other hand, model enhancements may result in differing findings and classifications.
Moreover, the representations of the spatial delimitation and quantification of the autochthonous air exchange processes are of special significance. The term “autochthonous” describes climatic events which occur locally or independently (that is without outside effects, e.g. extensive wind flows; the opposite is “allochthonous”). They are based in the climatic effectiveness of the particular utilization structures in their respective environments, and thus provide a sound basis for the derivation of concrete planning recommendations.