Air temperature changes in Toruń (central Poland) from 1871 to 2010

The article presents a detailed analysis of changes in air temperature in Toruń in the period 1871–2010 on the basis of homogenised monthly, seasonal and annual air temperature series which have been newly constructed (i.e. extended by the 50 years of 1871–1920). Over the 140-year study period, a sizeable and statistically significant increase of 0.1 °C per decade was found in the air temperature in Toruń. The greatest increases occurred for spring and winter, at 0.12 and 0.11 °C, respectively. A lesser warming, meanwhile, was recorded for autumn (0.10 °C/10 years), and particularly for summer (0.07 °C/10 years). The air temperature trends are statistically significant for all seasons. Air temperature differences between the monthly averages of three analysed subperiods (1871–1900, 1901–1950 and 1951–2010) and averages for the entire period under review rarely exceeded ± 0.5 °C. In all of these periods, the highest average air temperatures occurred in July and the lowest in January. The period of 1981–2010 had the highest frequency of occurrence of very and extremely warm seasons and years. Meanwhile, the highest frequency of very and extremely cool seasons and years was recorded in the 1940s and in the nineteenth century. In the period of 1871–2010, winters shortened markedly (by 7%) and summers lengthened by 3.8%. All of the presented aspects of air temperature in Toruń, which is representative of the climate of central Poland, are in close agreement with the findings of analogous studies of the same for other areas of Poland and Central Europe

The soil temperature at Polar Station in Horsund

The mean annual soil temperature, evaluated for the depths 5, 10, 20, 50 and 100 cm is negative and varies between -4.5°C in the subsurface layer and -4.2°C in the deeper parts of the analyzed profile. The soil is frozen through almost nine months in the year. During the lasting a short period spring and autumn there is an isothermy in the soil. Greater variability occurs in the subsurface layer. The layer between 50 and 100 cm accumulates the greatest amount of the heat. During the spring and the first half of summer the upper layer accumulates more heat. The soil temperature depends significantly on the variability of the air temperature. Additionally the soil temperature is influenced also by sunshine duration and snowcover depth. The annual variability of the soil temperature can be approximated with the first harmonic. Below the depth of 185 cm, the inter-annual soil temperature oscillations do not exceed 0°C. There are positive tendencies in variability of mean soil temperature time series at all depths. At the depth of 10 cm this tendency has a character of a statistical trend. Its value is +0.126°C/year in the period 1979-1999

Meteorological Extreme Events in Gdynia Until 1950

W pracy analizowano warunki termiczne, opadowe oraz anemometryczne w Gdyni w latach 1923-1950, które można uznać za ekstremalne. Wyniki z lat 1923-1950 oceniono w odniesieniu do wielolecia referencyjnego 1971-2000 oraz całego okresu pomiarowego 1923-2014. Analizowano rozkłady empiryczne i teoretyczne wybranych elementów meteorologicznych. W przypadku temperatury powietrza wyznaczono wartości kwantyli 5, 10, 90 i 95% rozkładów empirycznych temperatury maksymalnej i minimalnej oraz częstość występowania dni upalnych, fal gorąca i dni bardzo mroźnych. Wyznaczono sumę opadów w ciągu roku podczas dni z opadem o ekstremalnej sumie dobowej, liczbę dni z opadem silnym i bardzo silnym, a także najdłuższe ciągi kolejnych dni z opadem oraz bez opadów. Wyznaczono wartości kwantyli 10 i 90% rozkładu miesięcznych sum opadów. Wyznaczono wartości maksymalnej prędkości wiatru o okresie powtarzalności 5, 10 i 50 lat z zastosowaniem rozkładów GEV (ang. Generalized Extreme Value). Najbardziej znaczące różnice ekstremalnych warunków termicznych pomiędzy rozpatrywanymi wieloleciami stwierdzono w przypadku rocznego rozkładu temperatury minimalnej, który ulega systematycznemu przesunięciu w kierunku wyższych wartości. Wykazano również wzrost najniższych wartości temperatury maksymalnej oraz spadek liczby dni bardzo mroźnych. Różnice ekstremalnych warunków opadowych w poszczególnych wieloleciach mogą świadczyć o zwiększeniu intensywności opadów w niektórych miesiącach półrocza ciepłego oraz wzroście zagrożenia niedoborem opadów w ciągu całego roku. Dodatnie różnice maksymalnej prędkości wiatru, o możliwości wystąpienia co najmniej raz na 50 lat, mogą wskazywać na wzrost ryzyka strat spowodowanych wystąpieniem silnego wiatru.The aim of the research was to analyze the thermal, precipitation and anemometric conditions in Gdynia in the years 1923-1950, which can be considered as climate extreme. The results of the years 1923-1950 were evaluated for the reference period 1971-2000 and the whole measuring period 1923-2014. The empirical and theoretical frequency distributions of selected meteorological elements were analyzed. Statistical characteristics of the extreme thermal conditions (the values of 5, 10, 90 and 95% quantile of the empirical distributions) as well as the frequency of sweltering days, hot waves and very ice days were determined. Heavy and very heavy precipitation days, the amount of precipitation during days with extreme daily precipitation amount and the longest periods of consecutive days with precipitation and with no precipitation were determined. The maximum wind speed values of 5, 10 and 50-year return period was estimated with the use of Generalized Extreme Values analysis (GEV). The most significant differences in the extreme thermal conditions between the considered periods were found in the annual minimum temperature frequency distribution, which has been shifted towards higher values. It also showed an increase in the lowest values of the maximum temperaturę and a decrease in the number of very cold days. Results related to extreme precipitation conditions may indicate the intensity of precipitation events in some months of the warm season and an increase the risk of meteorological drought over the whole year. The expected return level of the extreme wind speed for 50 year return period, determined in relation to the periods considered, indicates an increase in the risk of losses caused by strong wind

Sea-air fluxes in the region of Norwegian Arctic

Tematyka praca dotyczy strumieni ciepła odczuwalnego i utajonego pomiędzy powierzchnią morza a atmosferą na wybranych akwenach morskich obszaru Arktyki Norweskiej w okresie 1991-2000. Obliczenia przeprowadzone na podstawie morskich obserwacji meteorologicznych, pochodzących z bazy ICOADS, oparto o zależności istniejące pomiędzy elementami meteorologicznymi (tzw. bulk formulas). Średnie miesięczne wartości strumieni ciepła odczuwalnego i utajonego są w ciągu całego roku dodatnie. Największe wartości strumieni są charakterystyczne dla miesięcy najchłodniejszych, w trakcie miesięcy ciepłych wartości strumieni są najniższe. Wielkość wymiany ciepła jest zależna od cyrkulacji wód oceanicznych. Większe wartości strumieni cechują obszary przemieszczania się ciepłych prądów.The aim of the paper was to characterize the sensible and the latent heat fluxes between sea and air in the area of the Norwegian Arctic in the period 1991-2000. The area under investigation covered the parts of the Barents Sea, Greenland Sea and Norwegian Sea from 70°N to 80°N between 10°W and 40°E. One of the most characteristic features of the selected area is the intensive oceanic circulation. The calculations were based on the data of International Comprehensive Ocean and Atmosphere Data Set (ICOADS). To calculate fluxes, the practical correlations between them and marine meteorological observations, called bulk formulas were used. The following elements were used for calculation of the sensible and the latent fluxes: sea level pressure, air temperature, dew point temperature, sea surface temperature and wind speed. The number of data used to calculate the sensible heat flux was almost three times great as in case of the latent heat flux. The August was represented by the greatest amount of data, the lowest number of observations was collected in case of December. The heat fluxes were prepared for 2.5 x 5 degrees latitude and longitude squares. Both the sensible heat flux and the latent heat flux between sea and air are positive within the whole year, the heat is transferred from the sea to the atmosphere. The greatest sensible heat flux is observed in January, its values vary from almost 90 W/m2 to 120 W/m2. The lowest values occur in July, the sensible heat flux exceeds 10 W/m2 only in the selected regions of the investigated area. Mean annual sensible heat flux varies between almost 50 Wm2 in the eastern part of the Barents Sea and 72 W/m2 in the vicinity of the western coast of Spitsbergen. The greatest values of the latent heat flux occur in January and vary from almost 80 W/m2 to 125 W/m2. The heat flux is the lowest within the summer months, in July its values do not exceed 20 W/m2. Mean annual latent heat flux varies between almost 50 W/m2 to about 70 W/m2. The relationship between the heat fluxes and oceanic circulation was stated. Regions of the warm sea currents occurring are characterized by the greater values of heat fluxes. The greatest heat fluxes were noted in the area influenced by the warm West Spitsbergen Current, the lowest ones, generally, occur in the region where cold East Spitsbergen Current enters the Barents Sea

Statistical downscaling of probability density function of daily precipitation on the Polish coast

The aim of this study was to recognize the possibility of downscaling probability density function (PDF) of daily precipitation by means of canonical correlation analysis (CCA). Sea level pressure (SLP) over Europe and the North Atlantic was used as a predictor. A skilful statistical model could be used to generate projections of future changes of precipitation PDF driven by GCM (General Circulation Model) simulations. Daily precipitation totals from 8 stations located on the Polish coast of the Baltic Sea covering the period 1961-2010 were used to estimate the gamma distribution parameters, and only wet days (i.e. ≥0.1mm) were taken in the analysis. The results of the Kolmogorov-Smirnov test and comparison of empirical and theoretical (gamma-distributed) quantiles proved that gamma distribution gives a reliable description of daily precipitation totals. The validation of CCA models applied to gamma parameters revealed that the reliable reconstruction of precipitation PDF is possible only for average long-term conditions. In the case of individual months/seasons the agreement between empirical and reconstructed quantiles is poor. This study shows the potential of modelling of precipitation PDF, however efforts should be made to improve model performance by establishing more reliable links between regional forcing and the variability of the gamma parameters

Zastosowanie ważonego filtru odległościowo-kierunkowego w różnych przestrzeniach barw w aspekcie nowoczesnych wskaźników jakości obrazów

Some promising results obtained by the application of the weighted Distance Directional Filter (DDF) for the filtration of an impulse noise are presented in the paper. An interesting fact to emerge is that the trade-off between the Vector Median Filter and the Basic Vector Directional Filter, which is the essence of the DDF, not only depends on the colour space used during calculations but also on the weighting coefficients within the filter mask. These results may form the basis for further research to identify a closer relationship among the filter parameters in order to develop the fast adaptive version of the nonlinear weighted filter.W artykule zaprezentowane zostały rezultaty filtracji obrazów kolorowych uzyskane w wyniku zastosowania ważonego filtru odległościowo-kierunkowego w celu zredukowania szumu impulsowego. Interesujący jest fakt silnej zależności wyników zastosowania tego filtru, będącego połączeniem wektorowego filtru medianowego z wektorowym filtrem kierunkowym, zarówno od przestrzeni barw, jak również współczynników wagowych maski filtru. Wynikowe obrazy uzyskane po zastosowaniu filtracji w rożnych przestrzeniach barw zostały ocenione za pomocą kilku nowoczesnych porównawczych wskaźników jakości omówionych w rozdziale 3. W publikacji zamieszczono reprezentatywne wyniki oceny jakości z użyciem wskaźnika podobieństwa strukturalnego (SSIM). Ich analiza pozwala na określenie zależności pozwalających na modyfikację algorytmu filtracji w kierunku maksymalizacji wartości nowoczesnych wskaźników jakości obrazu o wysokim stopniu korelacji z ocenami subiektywnymi. Uzyskane wyniki mogą stanowić podstawę dalszych badań w celu dokładniejszego zbadania właściwości filtracji DDF oraz opracowania opartego na niej szybkiego adaptacyjnego algorytmu nieliniowej filtracji obrazów kolorowych