In May 2019, Collection 2 of the Copernicus Global Land Cover layers was released. In addition to this, the new formulations were also applied in coupled mode in the COSMO model, resulting in improved diurnal cycles of near-surface temperature and dew point. In particular, a nocturnal warm bias is systematically reduced. Furthermore, the simulated amplitude of the diurnal cycle of the surface temperature is substantially increased. Additionally, the underestimation under dry conditions is reduced as well. In particular, the overestimation under wet conditions is reduced, also acting against an extensive drying of the soil during the annual cycle. The new formulation improves the simulated bare soil evaporation substantially. The new description of the bare soil evaporation in TERRA is based on a resistance formulation analogue to Ohm’s law, while the surface temperature is now based on the skin temperature formulation by Viterbo and Beljaars. In contrast, the diurnal cycles of the temperatures in the soil are overestimated instead. Furthermore, the amplitude of the diurnal cycle of the surface temperature is systematically underestimated. The results show that the bare soil evaporation simulated by the reference version of TERRA is substantially overestimated under wet conditions, and underestimated under dry conditions. The simulations were carried out in offline mode with atmospheric forcing data from the Meteorological Observatory Lindenberg–Richard-Aßmann-Observatory of the German Meteorological Service. Newly improved formulations of the bare soil evaporation and the surface temperature are presented, using the multilayer land surface scheme TERRA of the Consortium for Small-scale Modeling (COSMO) atmospheric model. Yet our results also underline the continued need to improve the description of built-up and impervious areas and the AHF in urban parameterizations. These results confirm the potential of LCZs in providing internationally consistent urban data for weather and climate modelling applications, as well as supplementing more comprehensive approaches. The LCZ-based approach worsens model performance for winter however, due to the underestimation of the anthropogenic heat flux (AHF). Additional improvements are obtained when using spatially varying urban thermal parameters instead of the hard-coded constants. For the summer period, advanced approaches (2) and (3) show almost similar performance and provide noticeable improvements with respect to default urban description (1). The test simulations are conducted for contrasting summer and winter conditions and are evaluated against a dense network of in-situ observations. In addition to the default urban description based on the global datasets and hard-coded constants (1), we present a protocol to define the required UCPs based on Local Climate Zones (LCZs) (2) and further compare it with a reference UCP dataset, assembled from OpenStreetMap data, recent global land cover data and other satellite imagery (3). This study compares three different approaches to define the UCPs for Moscow (Russia), using the COSMO numerical weather prediction and climate model coupled to TERRA_URB urban parameterization. Urban canopy parameters (UCPs) are essential in order to accurately model the complex interplay between urban areas and their environment. Urban planning solutions should take into account not only the climatic resistance of Arctic cities to the winter cold, but also be adapted to the occurrence of summer heat. ![]() In anthropogenically altered territories, the frequency of strong heat stress events can exceed that in the background areas by 1.7 times. During periods of the extremely hot weather events in Nadym, the territory meso- and microclimatic mosaicism clearly manifests itself. The article presents the detailed modeling results of the meteorological regime of the city within the framework of the COSMO-CLM model and the assessment of bioclimatic comfort using the Physiologically Equivalent Temperature (PET) index and Universal Thermal Climate Index (UTCI). Using the example of the city of Nadym (Yamalo-Nenets Autonomous Okrug), the authors have assessed the possibility of the summer urban heat stress occurrence and analyzed its spatial heterogeneity. At the same time, urban conditions can significantly affect the human heat perception due to the appearance of the urban heat island effect and other factors. Despite the fact, that against the background of global warming the Russian Arctic is still a region with severe winters and cool summers the likelihood of thermal stress conditions in summer is also increasing.
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