The methodological approach encompasses the data source evaluation process used in the Climate Analysis 2022. The climate assessment is the final product of the citywide climate modelling conducted for the State of Berlin. This modelling follows a sequence of interdependent processing steps, each contributing to the overall assessment while also yielding standalone, contained results. These include the climate modelling itself, the analysis of long-term weather station data, the processing of model outputs within the Climate Analysis (cf. Environmental Atlas 04.10), the analysis of trend developments of selected threshold days (cf. Environmental Atlas 04.12), and, lastly, the climate assessment presented here.
Model-Based Urban Climate Analysis
Within the scope of the overall project, a simulation was performed using the mesoscale climate model FITNAH with a horizontal resolution of 10 metres to represent a weather pattern typical of midsummer. The simulation was based on locally driven high-pressure weather conditions without the influence of synoptic winds – a scenario commonly used in urban climate studies.
It is common practice to derive urban climate planning guidelines based on a single meteorological scenario. For the 2022 edition, a locally-driven midsummer high-pressure pattern without the influence of synoptic winds was selected. The urban climate processes are most evident in this scenario. As such, it provides a solid basis for deriving planning guidelines that are useful in practice. As the results from the analysis phase may also be valuable for other use cases, such as development planning processes or impact assessments of measures, these datasets are also available via the Geoportal Berlin.
Spatial Units Considered
The main map of the PHK primarily distinguishes between three spatial units of assessment:
- settlement areas,
- green and open spaces, and
- traffic areas.
Areas are categorised as settlement areas if they are predominantly used for residential, commercial or public purposes. In residential areas in particular, people tend to spend time both during the day and at night. Green and open spaces include all areas designated primarily for recreation (such as parks, allotment gardens, and forests) or spaces that provide other climate and ecological services, such as farmland. From an urban climate perspective, green and open spaces serve a dual function. They are actively sought out during the day, offering relief from potential thermal stress and air pollution experienced in settlement and traffic areas. Especially at night, they generate and/or channel cold and fresh air, thus improving sleep quality for nearby residents, even during periods of climatic stress. By contrast, traffic areas mainly serve as places where people spend time temporarily during the day. They are used for extended stays (e.g. city squares) or as a means to an end to reach a destination (e.g. commuting to work or shops).
The geometric units of the ISU5 serve as the spatial reference (Urban and Environmental Information System 2020, available in German only). Each unit was uniquely assigned to one of three land-use classes, based on the ‘area types’ defined in the Environmental Atlas (cf. 06.08 Environmental Atlas 2020, SenStadt 2020).
Of Berlin’s total urban area spanning approximately 890 km², this project classifies 389 km² (43.8%) as settlement areas, 326 km² (36.6%) as green and open spaces, and 121 km² (13.6%) as traffic areas. The remaining 6% consists of flowing and standing waters. Open bodies of water play a rather important role in urban climate processes, due to their mitigating or ‘compensatory’ effect. However, they are only included in the PHK for reference purposes, as bodies of water are generally not subject to conversion or development pressure.
The approach, underlying data sources and methodology of the process used to update the climate data aim to maximise the level of detail and coverage of the resulting findings. In view of the dynamic development in the city, however, the baseline conditions used for the assessment can change more quickly in individual areas than the update cycle of the Environmental Atlas can record. It is therefore recommended to display the layer with current aerial images in the Geoportal in order to check the area and compare it with the factual data of the PHK. This allows conclusions to be drawn about the usability of the evaluation results.
Urban Climate Assessment
The methodological concepts of the individual maps are outlined in the technical documentation (available in German only).