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The aim of this paper was to characterize the warm and dry compound events (WD days) in Poland during the period of 1966–2023, focusing on assessing the frequency and intensity of such events and their spatial and temporal variability, as well as on the driving factors of warm and dry compound events. WD days are those days that have a maximum temperature equal to or higher than the 90th percentile and the precipitation on that day and the 14 preceding days are equal to or less than the 25 percentile. During 1966–2023, the frequency of WD days increased significantly, mainly in April, the summer months, and December. Higher temperatures favored the occurrence of WD days from March to November, but, in winter months, the heat did not favor the occurrence of WD days. The exception was December, when high temperatures in the first part of the analyzed period did not favor the occurrence of a dry day, whereas, in the second part, it did. The strongest influence on the frequency of WD days had the East Atlantic pattern, where air flowed over Poland from the southwest. Warm and humid air flowing from the Atlantic Ocean must overcome the mountain barrier; therefore, it flows to Poland as warm and dry air. From spring to autumn, the WD days were related to an increase in the geopotential height in central Eastern Europe, and, in the winter, they were related with blocking over the Balkans. [ABSTRACT FROM AUTHOR]

The aim of the paper was to assess the robustness of four bias correction techniques: simple bias correction, distribution based bias correction, delta change and distribution based delta change. Data from nine RCM simulations of CORDEX project and 41 Polish weather stations were used. The methods were calibrated in the period 1971–1985 and evaluated in 1991–2005. The improvement in mean, 10th and 90th percentiles was shown, without significant differences among methods. For 1st and 99th percentiles the improvement was generally weaker and simple methods seem to be more robust than the distribution based ones. Strong differences between individual models were found, so the use of model ensemble is recommended.

This work gives an overview on how the projected changes in the extremes in Poland might impact human health and economy. For that purpose, statistically corrected data from 7 regional climate models were used. A significant increase of extreme hot events (i.e. heat waves, tropical nights) is projected for Central and Southern Poland for the end of the 21st century which might seriously affect a society living in large urban areas. Less extreme cold events improve thermal comfort in winter. The negative impact of the warming will affect energy systems with higher demand for electricity in summer and agriculture: an earlier beginning of the growing season and flower blooming will enhance the risk of frost damages in spring, whereas excessive heat will reduce yields in summer. Polish tourism should benefit from higher thermal comfort (except for hot July and August in the far future and warming in the winter season bringing snow cover depletion in the near future). [ABSTRACT FROM AUTHOR]

The research focuses on the analysis of PM10 and PM2.5 concentrations variability at 11 stations in selected urbanized areas of Poland (Tricity, Poznań, Łódź, Kraków). Methods comprised: the analysis of basic statistical characteristics in yearly/monthly/daily/hourly scale and threshold exceedance frequencies. Also, correlations between PM10 and meteorological variables were investigated. GEV distribution analysis allowed the estimation of the return levels of monthly maxima of PM10 and PM2.5. Results show that in Tricity there are fewer than 5 % of days with PM10 and PM2.5 threshold exceedance. In Kraków, the standards are only met during summer and the frequency of daily PM limit exceedance in winter was around 65–90 %. GEV analysis indicates that 10y return level of PM10 monthly maximum daily average do not usually exceed 250 μg/m3 at most of the stations (Kraków agglomeration is an exception here). In winter, the meteorological conditions unfavourable to the pollutant's dispersion comprise: high-pressure systems, stable equilibrium in the atmosphere and limited turbulence occur quite often together with low wind speed and reduced height of the planetary boundary layer. [ABSTRACT FROM AUTHOR]

The level of the groundwater table depends not only on the weather conditions, but primarily on the hydrogeological properties of the substrate and the thickness of the aeration zone. The paper analyzes the relationship between precipitation and the groundwater table level response. For this purpose, weekly datasets of groundwater table levels (Łódź and Ciosny sites) and daily precipitation totals (Łódź-Lublinek and Ciosny) were studied for the period 1999-2013. During the cold half of the year the increase of the groundwater table level was found for relatively small precipitation (< 10 mm per week). On the contrary, in the warm half of the year a much higher precipitation totals (> 20 mm per week) are required for that increase. For the shallower well (Łódź), the groundwater table level response to precipitation is more dynamic. In the deeper well (Ciosny) the lower fluctuations of amplitude and longer response to precipitation were noticed. For the same amount of precipitation, the increase in the groundwater table level for the shallower well is twice as high as for the deeper one. [ABSTRACT FROM AUTHOR]

The main aim of this study was to investigate the variability of high daily precipitation totals between the urbanized area of Łódź and the surrounding rural areas. Data collected at three stations located in the city, on the outskirts and outside of the city were analyzed. According to the indices proposed by the Expert Team on Climate Change Detection and Indices (ETCCDI), higher and more intensive daily precipitation than in the city was observed at the rural station. High precipitation events were associated with air masses passing through western and south-western Europe, according to the HYSPLIT model of backward trajectory analysis. The highest daily precipitation totals were found for the cyclonic circulation. For the station located outside the city, the highest rainfall was observed under the conditions of western and southwestern inflow, however, for the urban stations high precipitation totals were observed during eastern inflow as well. [ABSTRACT FROM AUTHOR]

Krakow is one of the most polluted cities in Poland. The dust fraction of 2.5 μm (PM2.5) has a significant impact on human health. The greatest concentration of PM2.5 was found for the cold half year (especially in February and December) and in the most densely built-up area of the city center. The worst air quality occurs in the evening and morning (peak traffic) hours. In the cold half year the highest concentration of PM2.5 was observed for the south-western and southern air masses advection, while in the warm half year for the south eastern and southern advection. The increase in wind speed is followed by a considerable decrease of the concentration of PM2.5 in all monitoring sites. [ABSTRACT FROM AUTHOR]

In the paper the characteristics of one of the most valuable rivers in Łódź, the Jasień, are described. The Jasień is a unique example of a river once working for industry but now existing as untapped tourism potential despite its negative image and even being partly forgotten. The description of the most valuable historical hydro-technical work along the river's course is given with some useful historical information. In the summary, a suggestion of how the river bank might become a trigger for studying Łódź's history, as its industrial development was so strongly related to the river network. [ABSTRACT FROM AUTHOR]