EGU21-9102, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Building a new high-density air temperature measurement network in two Swiss cities

Julien G. Anet1, Sebastian Schlögl2, Curdin Spirig1, Martin P. Frey3, Manuel Renold3, and Karl G. Gutbrod2
Julien G. Anet et al.
  • 1Zurich University of Applied Sciences, Centre for Aviation, School of Engineering, Winterthur, Switzerland
  • 2meteoblue AG, Basel, Switzerland
  • 3Zurich University of Applied Sciences, Institute for Data Analysis and Process Design, School of Engineering, Winterthur, Switzerland

With progressive climate change, weather extremes are very likely to become more frequent. While rural regions may suffer from more intense and longer drought periods, urban spaces are going to be particularly affected by severe heat waves. This urban temperature anomaly, also known as “urban heat island” (UHI), can be traced back to different factors, the most prominent being soil sealing, lower albedo and lack of effective ventilation.

City planners have started developing mitigation strategies to reduce future forecasted heat stress in urban regions. While some heat reduction strategies are currently intensely scrutinized and applied within pilot projects, the efficiency of latter mitigation actions can be overseen due to the low density of reference in situ air temperature measurements in urban environments. The same problem applies when trying to benchmark modeling studies of UHI as the amount of benchmarking data may be insufficient.

To overcome this lack of data, over the last two years, a dense air temperature measurement network has been installed in the Swiss cities of Basel and Zurich, counting more than 450 sensors. The low-cost air temperature sensors are installed on street lamps and traffic signs in different local climate zones of the city with an emphasis on street canyons, where air temperatures are expected to be the largest and most of the city’s population lives and works. These low-cost sensors add valuable meteorological information in cities and complement the WMO reference stations.

Air temperature measurements from the low-cost sensor network were controlled for accuracy, reliability and robustness and homogenized in order to minimize radiation errors, although 40% of the stations were equipped with self-built radiation shields, allowing an efficient passive ventilation of the installed sensors.

We demonstrate the strength of our network by presenting first results of two exemplary heat waves that occurred in July 2019 and August 2020 and show that a) the radiation-error corrected datasets correlate well with different high-quality reference WMO stations, and b) the existence of urban heat islands in Zurich and Basel can be well confirmed, showing significant air temperature differences of several degrees between rural and urban areas.

The results demonstrate the advantages of a high-density low-cost air temperature network as a benchmark for future urban heat islands modelling studies.

How to cite: Anet, J. G., Schlögl, S., Spirig, C., Frey, M. P., Renold, M., and Gutbrod, K. G.: Building a new high-density air temperature measurement network in two Swiss cities, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9102,, 2021.


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