Cities alter the thermal regime of urban rivers in very variable ways which are not yet deciphered for the territory of Romania. The urban heat island of Suceava city was measured in 2019 and its impact on Suceava River was assessed using hourly and daily values from a network of 12 water and air monitoring stations. In 2019, Suceava River water temperature was 11.54 °C upstream of Suceava city (Mihoveni) and 11.97 °C downstream (Tişăuţi)—a 3.7% increase in the water temperature downstream. After the stream water passes through the city, the diurnal thermal profile of Suceava River water temperature shows steeper slopes and earlier moments of the maximum and minimum temperatures than upstream because of the urban heat island. In an average day, an increase of water temperature with a maximum of 0.99 °C occurred downstream, partly explained by the 2.46 °C corresponding difference between the urban floodplain and the surrounding area. The stream water diurnal cycle has been shifted towards a variation specific to that of the local air temperature. The heat exchange between Suceava River and Suceava city is bidirectional. The stream water diurnal thermal cycle is statistically more significant downstream due to the heat transfer from the city into the river. This transfer occurs partly through urban tributaries which are 1.94 °C warmer than Suceava River upstream of Suceava city. The wavelet coherence analyses and ANCOVA (analysis of covariance) prove that there are significant (0.95 confidence level) causal relationships between the changes in Suceava River water temperature downstream and the fluctuations of the urban air temperature. The complex bidirectional heat transfer and the changes in the diurnal thermal profiles are important to be analysed in other urban systems in order to decipher in more detail the observed causal relationships.

<p>In cities the chemical parameters of the urban atmosphere are being influenced, mainly negatively, by the daily human activities. The urban agglomeration of Suceava (from the NE of Romania) amounted to 116404 inhabitants as per the census from 2011. Their quality of life depends directly on the quality of the air inhaled, and this is being affected by the variable emissions of the transport and industrial sectors and by the household activities. The Municipality of Suceava is an important commercial center and, at the same time, a tourist city.</p><p>The general objective of the study consists in the evaluation of the air quality of Suceava Municipality, on the basis of the hourly data from the stations SV1 (urban background) and SV2 (industrial background) from the interval January 2009 - October 2019, on the basis of five chemical indicators: NO2, SO2, CO, O3 and PM10. The main objectives are: i) the identification of the fluctuations in time of the daily or hourly average concentrations of these emissions with the outlining of their daily or annual regime; ii) the comparison of the air quality in the neighbourhoods with residential function from the central and central-southern areas (Zamca, Marasesti, George Enescu, Areni, Obcini and so on) with the one from the industrial platform vicinity, and iii) the releasing of some accurate evaluations based on data from monitoring, which to classify in different levels of quality the air breathed in by humans.</p><p>Results. In Suceava the concentrations of NO2 (with hourly indices of quality evaluated as being excellent in 96,51% of cases at SV1 and 93,51% of cases at SV2), SO2 (with hourly indices of quality evaluated as being excellent in 99,79% of cases at SV1 and 99,03% of cases at SV2) and CO (with indices of excellent quality of the air in 99,78% of the hours of observations at SV1 and 97,32% at SV2) are not capable to raise real problems from the perspective of their impact on human health. In the case of O3, in 1,67% of the hours of observations from SV1 the concentration of this gas exceeded the target value for the protection of human health (120 μg/mc). The situation is not alarming due to the reduce percentage held by these situations and to the limitation of the areal to a single monitoring point. In the case of PM10 the concentration does not raise problems at SV1 station where the proportion of time with exceedings of the daily limit value for human health protection is on average 1,3 days/year<sup>-1</sup>, but at SV2 the daily limit values are being exceeded in 35 day/year<sup>1</sup>. The interval October - March, with thermal inversions, persistent fog and low stratiform clouds, is the critical one related to this pollutant.</p><p>Conclusions. On the background of the industrial decline that followed after 1989, the quality of the air from the atmosphere of Suceava has increased. The problem of the particles in the areal of the industrial platform and Burdujeni neighbourhood stays a current one. </p>

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<p><em>Introduction</em>. Detailed knowledge of the thermal influence of the cities is a necessity of the current climatological research. In the case of smaller cities, such as Suceava, measuring the thermal influence of the city is a challenge due to several factors deriving from the small size of the city, its polynuclear fragmentation, the specificity of the urban topography, of the hydrographic network and of the land use/land cover. The main purpose of this study is to highlight the thermal influence of the city for several specific temporal entities: i) at the multiannual level, ii) for the winter season and for the time interval 2.30-4.30 during the winter, iii) for the spring season, iv) for the summer season and for the time interval 12.30-14.30 during the summer and v) for the autumn season, respectively.</p> <p><em>Data and methods</em>. Having available hourly data of the air temperature from 1 January 2019 to 31 December 2022 obtained from a private network of 27 stations, plus data from Suceava Meteorological Station (SvMS), Salcea Airport Meteorological Office and the stations SV1 and SV2 belonging to the National Air Quality Monitoring Network, we conducted a detailed analysis of the variation and distribution of the air temperature values for Suceava Metropolitan Area (SvMPA). SvMS was taken as a reference for those 14 urban stations, 12 suburban stations and the 4 stations placed in the forests around Suceava and in Zamca urban forest.</p> <p><em>Results.</em> During the whole analyzed period, the thermal averages were 9.5°C at the forest stations, 9.8°C at Suceava Meteorological Station, 10.2°C at the suburban stations and 10.7°C at the urban stations. At the urban stations SV2, BUO, CCO and SV1 the thermal advance in respect of SvMS was between 1 and 1.3°C, and at the forest stations MDP and SIL the thermal gap in respect of SvMS was between 0.2 and 0.9°C. In winter the temperature was 0°C at SvMS and at the forest stations, rising to 0.3°C at the suburban stations and to 0.5°C at the urban stations. In summer, the coldest was in the forest (19.5°C), the temperature rising to 19.9°C at SvMS, to 20.6°C at suburban stations and to 21.3°C at urban stations. Springs are cooler than autumns (by 1.4°C for the whole of SvMPA). On this background, in spring, the thermal advance of the urban stations (9.7°C) over the forest ones (8.5°C), SvMS (8.8°C) and suburban stations (9.2°C) is obvious, and also in autumn (T urban stations = 11.0°C, T forest = 9.9°C, T SvMS = 10.4°C, T suburban stations = 10.6°C).  </p> <p><em>Conclusions.</em> At those 14 urban stations the average thermal difference for the interval 1 January 2019 - 31 December 2022, compared to SvMS was 0.9°C (the difference ranged from 0.5°C in winter to 1.4°C in summer). In summer, in the hourly interval 12.30 - 14.30 the overall thermal differences (urban stations - SvMS) rose to 3.1°C, and for the CCO station in the city centre to 5.4°C. </p>

<p>Urbanization and agriculture intensification accelerate the land use and cover conversions unbalancing the surface energy budget. Land Surface Temperature (LST) represents the land radiative skin temperature which is derived from solar radiation and is one of the most important indicators of local climate variability. The present work aims to analyze the effects of land use land cover changes (LULCC) on spatial pattern distribution of Land Surface Temperature in the first ring of Suceava Metropolitan Area over the last 35 years. In order to meet our demand we have conducted a spatio-temporal analysis using Geographical Information Systems (GIS) and Remote Sensing (RS) techniques. We have used two satellite images from Landsat 5 TM (23 August 1985) and 8 OLI/TIRS (23 August 2020) in order to create land cover maps by applying a supervised classification with spectral angle algorithm and to estimate Land Surface Temperature through the Plank Equation. Given that we have applied the supervised classification to define the four major land cover classes (bare soil, built-up area, vegetation and water bodies) we have used the classification-based method to determine the surface emissivity. The overall accuracies of the land cover maps of 1985 and 2020 were found to be 93.45%, and 96%, while the Kappa coefficients were found to be 0.90 and 0.94 for the years 1985 and 2020, respectively. The land cover change matrix showed that during the study period, 140.67 km<sup>2</sup> representing 34.60% of the total study area faced mutual conversion among four land cover types while 265.90 km<sup>2</sup> representing 65.40%  of the total study area remained unaltered. More exactly, built-up area and vegetation surfaces increased by 78.31% and 3.78%, respectively, while bare soil and water bodies decreased by 38.71% and 10.21%, respectively. LSTs found in the study area ranged from 18.27 to 33.91°C and 21.67 to 40.48°C for the years 1985 and 2020. The increases of spatially distributed maximum, mean and minimum LST were found 6.57°C, 3.84°C and 3.40°C, respectively. This means a LST increase by around 0.11°C per year for the study period of 35 years. Moreover, the results showed that covers without vegetation and artificial surfaces have recorded the highest temperatures: 26.18 to 30.11°C and 25.49 to 29.66°C for bare soil and built-up area, respectively. The increases of mean LSTs were 4.16°C, 3.96°C, 3.92°C and 3.53°C for the bare soil, vegetation, built-up area and water bodies, respectively, during the study period. On the other hand, in 1985 the highest maximum LST was 33.91°C in the built-up area followed by 31.26°C, 28.11°C and 24.90°C by bare soil, vegetation and water bodies, respectively, while in 2020 the highest maximum LST was 40.48°C in the built-up area followed by 35.28°C, 33.54°C and 28.98°C by bare soil, vegetation and water bodies, respectively. Based on the above findings, policymakers and urban planners should be concerned about future urban expansion and agriculture management in order to reduce the LST-related urban heat island or drought intensification problem.</p>