Urbanization leads to a profound transformation of the countryside and, hence, to a shift in local climate. The construction of buildings, paving of streets, sealing of areas and reduction of vegetation are important aspects. Among other consequences, these changes result in decreasing wind speeds, less evapotranspiration, and increasing uptakes of solar radiation. All of the mentioned factors cause a rise in temperatures compared to the rural surroundings of a city, generating the so called Urban Heat Island (UHI). In order to study various aspects of the urban climate, we have different research approaches which are explained in the following.
The climate bus
Our van is equipped with instruments for measuring the meteorological parameters which matter most in terms of studying Urban Climate. These parameters include temperature, humidity, radiation, and wind speed which are measured continuously while driving through cities. Besides, the van is endued with a GPS sensor, assigning every measurement to a certain location. The vehicle enables us to cover long distances with high temporal resolution climate data.
Stationary sensors are installed to assess the microclimate of different locations within an urban area. This allows us to investigate daily minima and maxima as well as seasonal variations. The sensors are protected by a radiation shield and are set to measure air temperature and relative humidity in 30min intervals. We maintain a network in the city of Mainz as well as in three different villages throughout Europe in order to assess the UHI in small urban areas as well.
At many locations throughout Mainz, we installed Dendrometers along with the temperature/humidity sensors. These instruments record the growth of trees as well as the daily shrinkage connected to the transportation of water within the trees. This provides us a better understanding of the physiology of different tree species in urban areas related to local climate, especially with regard to water availability and drought stress.