ИСТИНА

In the modern era of modeling and remote sensing, in situ urban meteorological observations still remain critically important for validating urban climate models, remote sensing products, and developing data-driven ML models. To collect such data, more urban meteorological networks are being deployed, along with the development of new methods to use opportunistic sensing technologies, such as citizen weather stations. However, the Arctic—a large and unique region—has been largely overlooked in urban meteorological observations and urban climate studies in general until recently. To address this gap, we established the Urban Heat Island Arctic Research Campaign (UHIARC) in several Russian Arctic cities (Konstantinov et al., 2018, https://doi.org/10.1088/1748-9326/aacb84; Varentsov et al., 2018, https://doi.org/10.5194/acp-18-17573-2018). Here we present the results of long-term meteorological observations from the UHIARC campaign conducted over the past decade (2015-2023) in seven cities in North-Eurasian Arctic: Murmansk, Apatity, Vorkuta, Salekhard, Nadym, Novy Urengoy, and Norilsk, with many sites monitored for several years, and resulted harmonized observational dataset. Collected data offers new insights into UHI climatology in the Arctic. We demonstrate that Arctic UHIs are significantly stronger in winter, with mean winter intensities ranging from 0.8 to 1.8 K, while mean summer intensities do not exceed 0.5 K. Extreme UHI intensities also peak in winter, reaching 5-6 K at the 95th percentile and 7-8 K at the 99th percentile. These extremes typically occur under a strongly stable ABL with intense temperature inversions. Among the studied cities, Norilsk and Nadym exhibited the strongest UHIs, while Murmansk, the largest Arctic city, showed the weakest UHI effect due to its coastal position near an unfreezing sea inlet, leading to less stable atmospheric stratification in winter. The study was supported by Russian Science Foundation, project no. 23-77-30008, and by Ministry of Science and Higher Education of the Russian Federation, project no. FSSF-2024-0023.