Comparison of parallel temperature measurements from digital thermometers and mercury-in-glass thermometers for cooperative observation network in Catalonia

The Minamata Convention on Mercury is a global treaty to protect human health and the environment from the adverse effects of mercury. The Regulation (EU) 2017/852 of the European Parliament and of the Council of 17 May 2017 on mercury, came into force in 2020 and banned all production, import and export of observing instruments that containing mercury in Europe.

In Meteorological Service of Catalonia our meteorological observing network have long involved the use of mercury-in-glass thermometers, with more than 130 observers. The replacement of this instruments is required, and a comparative study has been done in Catalonia with two digital thermometers. Those new instruments provide a simple and easy solution by the observers, while requiring the observer to go to the weather station every day. This allows the collection of the rest of the essential meteorological variables such as precipitation, cloud cover and type, visibility, wind direction and wind Beaufort, etc.

Since December 2022, two digital thermometers were installed into a medium wooden screen in Calonge (Girona, Catalonia) where there are a typical mercury-in-glass thermometers. One of these thermometers is from Metspect, and the other one is from Navimet. Within more than one year of parallel measurements, this study explains the results obtained and a characterization of the performance. The advantages and disadvantages of each digital device will be exposed. The results will be used by the Meteorological Observers Network (XOM) from Meteorological Service of Catalonia (SMC) to select which device it uses as a reference for this cooperative network in Catalonia.