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Rain in Charlottenburg, sunshine in Kreuzberg

In Charlottenburg it’s 18 degrees and raining, while in Kreuzberg it’s 23 degrees and people are heading for the Prinzenbad open-air swimming pool. These temperature differences in one and the same city have doubtless been noticed by everybody. Another phenomenon is the urban heat island, meaning that it is warmer in the city than in the surroundings. For instance, depending on weather conditions, it can be up to 10 kelvin warmer in inner city areas than in surrounding rural areas, above all at night. This spatial heterogeneity is a challenge for urban climate research.

It was to observe and better understand these phenomena that the citizen science project OpenUCO (Open Urban Climate Observatory) was launched in 2021. OpenUCO is a collaborative research project by TU Berlin, FU Berlin and the general public in Berlin, and is funded by the Berlin University Alliance (BUA). Since summer 2022, members of the public in Berlin have been taking weather measurements by means of monitoring stations in their garden plots both inside and outside of the Ringbahn railway line. “We’re making use of the participation of local people, because the monitoring stations that already existed in Berlin weren’t able to reflect the situation in the city as a whole,” says Dr. Jana Ulrich, a researcher involved in the OpenUCO project at the Chair of Climatology at TU Berlin.

The project’s scientific director is Dr. Fred Meier, head of the Urban Climate Research Group at the Chair of Climatology of TU Berlin’s Institute of Ecology. Meier is one of the managers of the UCO (Urban Climate Observatory) Berlin, which operates monitoring stations of its own in the city. As a result, TU Berlin is putting its urban climate expertise at the disposal of the research project.

FU Berlin’s involvement is through the Statistical Meteorology Research Group at the Institute of Meteorology, directed by Professor Dr. Henning Rust. It is here that the citizens’ weather station MESSI was developed in collaboration with the Hans Ertel Center for  Meteorological Research. The simple digital weather station can measure precipitation, air temperature and solar radiation, and transmit the data collected to the research platform.

The citizen scientists for their part maintain the weather station and can view their own readings via a web application. The data they gather is quality-controlled by the professional scientists and published.

The meteorological data recorded in this way supplements that from the existing scientific measuring network of the Deutscher Wetterdienst (German Weather Service) and the Urban Climate Observatory Berlin. With the help of the general public, the professional scientists hope to find answers to questions such as: “What spatial differences are there in heavy rainfall?”, “What effect do green spaces have on air temperature in the city?” and “How big are the temperature differences compared to sealed surfaces?”

The project has met with great interest among Berliners. Since the project started, around 100 monitoring stations have been set up and maintained by Jana Ulrich’s team. “They find it fascinating to see what’s happening in their gardens if, for example, they go away for a short time,” Jana Ulrich says, “because they have the possibility to follow the data live via the web app.” Participants can view the data generated in their garden – e.g., air temperature, air humidity, and precipitation – on their smartphone and can also use it to adjust how their garden plot is watered. Together with professional scientists from OpenUCO the measurement data was evaluated at a workshop. Data gathered in the first week of July showed, for instance, that garden plots were on average up to five kelvin cooler than an internal courtyard at Hackescher Markt.

The aim of the research is to build up an open meteorological measuring network in Berlin for investigating the negative climatic effects of urban growth, which are harmful to the health of the urban population and are intensified by climate change. Combined with the observations from the city’s measuring network and from Berlin’s precipitation radar that was installed in spring 2022, the measurements provide a new data pool for the investigation of the urban climate. “We can record in finer detail how heavy rainfall is distributed across the urban area and what the effect of garden plots on the urban climate is,” Jana Ulrich says. The project continues until the end of 2023. “We’ve still got to evaluate all the collected data by then.” Jana Ulrich is eagerly looking forward to getting the results. For the moment, anyone can view the locations and live measurement data of all the monitoring stations. The TU Berlin and FU Berlin weather radar is freely available online, too.

Dagmar Trüpschuch

Oliver Rudzick und Artur Gantzckow in ihrem Kleingarten vor der MESSI-Wetterstation. © Saskia Uppenkamp

Oliver Rudzick and Artur Gantzckow in front of the MESSI weather station in their allotment garden.

© Clara Nitzsche