Enhance Urban Climate Understanding from a Comprehensive Meteorological Measurement Network

Urban areas are increasingly confronting significant environmental challenges, including elevated levels of air pollution, extreme temperature fluctuations, and intense precipitation events. As climate change continues to advance, these issues are expected to become more frequent and severe, resulting in potentially substantial economic losses and heightened risks to public health and safety. Understanding urban climate dynamics and their changes is therefore critical, with heatwave management playing a key role in adapting to these impacts.

Most locations within urban areas typically do not fulfill the World Meteorological Organization (WMO) guidelines for conducting meteorological measurements. As a result, official weather stations are often situated on the outskirts of cities, leading to an underrepresentation of the Urban Heat Island (UHI) effect. While national weather services have begun addressing this gap by employing station pairs consisting of a rural and urban WMO station to capture the UHI effect, this approach cannot adequately represent the small-scale temperature variations within urban environments.

This study focuses on the development and results of an urban meteorological measurement network in Basel, Switzerland which is one example showing that it is essential for accurately assessing the unique thermal dynamics of cities.

In 2019, a comprehensive measurement network comprising over 200 low-cost IoT sensors was established in Basel, Switzerland. This network monitors key meteorological parameters including air temperature, precipitation, and relative humidity. Data collected from the network indicate that the air temperature within urban areas can differ by up to 5.4 °F compared to their rural surroundings, on average. These variations are attributed to differences in material composition and surface properties, which influence the thermal characteristics of the environment and directly affect air temperature and its variability. The network was enhanced with the addition of "Black Globe" sensors, designed to quantify heating or cooling effects by measuring mean radiant temperature. These stationary sensors enable the development of long-term climate time series, which are essential for driving predictive models. These models provide critical data for urban planners and the general public, facilitating informed decision-making. Additionally, by incorporating infrared camera measurements, the network has been able to assess the impact of various urban adaptation strategies - such as street whitening and strategic tree planting - on the microscale urban climate of Basel.

These findings underscore the utility of the sensor network in evaluating the effectiveness of climate adaptation measures at a granular level, thereby contributing valuable insights into urban climate dynamics and providing a robust data foundation for city decision-makers.