Merging two city-level weather-sensor networks to analyse urban heat island conditions in Tallinn, Estonia

Urban areas are characterised by a (compared to rural surroundings) elevated temperature level, which is specifically problematic during heat waves. Climate change is increasingly exacerbating the problem. We investigate urban heat island conditions (UHI) for the coastal city of Tallinn, located at the southern shore of the Gulf of Finland in the north-eastern part of the Baltic Sea region. For that, we merge observations of two city-level weather sensor networks, available from June 2022 in hourly resolution. One network was designed to investigate the value of green (compared to grey) spaces from a climate perspective (18 sensors), while the other one consists of weather sensors alongside the road network of Tallinn (>50 sensors). Both networks are supported by quality-controlled data provided by the national weather service of Estonia. Major attention will be put to quality-checking and comparisons of observations generated by both networks, paving the way for analysing the data from an urban climate perspective – considering local climate zones and land-use factors as well as the influence of the sea. We will be focussing on heat conditions during the 2022 summer, with additional analyses planned for winter 2022/23. The results of this study will help city planners optimising climate adaptation in Tallinn and support the communication of weather- and climate-related risks – especially linked to heat conditions – to the citizens of the city. Being the Green Capital of Europe during the year of 2023, our investigations will provide unique data for decision-makers related to green city planning and UHI reduction in Tallinn.