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Fluctuations of ice in a lake due to the impact of the North Atlantic Oscillation (1960/61–2009/10) – a case study of Łebsko Lake

Młodzik Artur, Cieśliński Roman, Chlost Izabela

Oceanologia

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2024

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Vol. 66 (2)

153--166

EN

The paper represents an attempt to understand the impacts produced by the North Atlantic Oscillation on the ice cover regime of the largest coastal lake in Poland situated in the northern part of the country. The purpose of the study was to estimate the impact of the North Atlantic Oscillation on selected ice cover parameters. The study also attempts to examine other factors that may affect its significant impact on observed changes in the climate. Water temperature data are used to assess temperature conditions in aqueous ecosystems as well as determine the heat absorption capacity of these systems. This allows one to then determine cooling rates in the event of ice cover formation. The data analysis provided in the paper focuses on selected characteristics of ice cover conditions (i.e. dependent variables) including the number of days with ice and maximum ice thickness in relation to NAO index changes (i.e. independent variables) for the reference period 1960/61–2009/10. In addition, the paper divides the studied period into 10-year subperiods in order to capture the weakest and strongest phases of NAO and assess the extent to which they affect the duration of ice cover. A large increase in the mean air temperature (1.8°C) occurred in the years 1960–2010. Trendline analysis indicates that the number of days with ice cover declined by about 60 days and the maximum thickness of ice cover decreased by about 10 cm. Oceanographic research employs satellite image data in order to accurately assess human impact. Therefore, ice cover forecasts generated for consecutive winter seasons may become an important tool in this type of assessment.

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Spatio-temporal analysis of annual rainfall in Crete, Greece

Varouchakis E. A., Corzo G. A., Karatzas G. P., Kotsopoulou A.

Acta Geophysica

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2018

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Vol. 66, no. 3

319--328

EN

Analysis of rainfall data from the island of Crete, Greece was performed to identify key hydrological years and return periods as well as to analyze the inter-annual behavior of the rainfall variability during the period 1981–2014. The rainfall spatial distribution was also examined in detail to identify vulnerable areas of the island. Data analysis using statistical tools and spectral analysis were applied to investigate and interpret the temporal course of the available rainfall data set. In addition, spatial analysis techniques were applied and compared to determine the rainfall spatial distribution on the island of Crete. The analysis presented that in contrast to Regional Climate Model estimations, rainfall rates have not decreased, while return periods vary depending on seasonality and geographic location. A small but statistical significant increasing trend was detected in the inter-annual rainfall variations as well as a significant rainfall cycle almost every 8 years. In addition, statistically significant correlation of the island’s rainfall variability with the North Atlantic Oscillation is identified for the examined period. On the other hand, regression kriging method combining surface elevation as secondary information improved the estimation of the annual rainfall spatial variability on the island of Crete by 70% compared to ordinary kriging. The rainfall spatial and temporal trends on the island of Crete have variable characteristics that depend on the geographical area and on the hydrological period.

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Zmiany klimatu w holocenie

Marks L.

Przegląd Geologiczny

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2016

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Vol. 64, nr 1

59--65

EN

Climate has been changing since the beginning of the Earth. During the Holocene the climate has not changed much but there were both warmer and cooler episodes. Varying insolation is the main reason for climate change during the Holocene. All other reasons, including among others changes of the Earth orbital parameters (Milankovitch cycles) and thermohaline oceanic circulation played a secondary role. Occasional volcanic eruptions were climatic disasters but usually on a local or regional scale and only in a short time. A record of climate change during the Holocene indicates its great influence on the development and decline of ancient civilizations and societies. From a geological point of view there is no reasonable record suggesting that contents of CO2 in the atmosphere played a predominant role of in the ongoing climate change during the last century.

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Zmienność termicznego charakteru okresów zimowych w Polsce i jej przyczyny

Marsz A. A., Styszyńska A.

Automatyka, Elektryka, Zakłócenia

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2015

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Vol. 6, Nr 4(22)

118-127

PL

Praca przybliża problematykę funkcjonowania fenomenu klimatycznego Oscylacji Północnego Atlantyku (Norh Atlantic Oscillation–NAO) oraz omawia jej wpływ na kształtowanie charakteru termicznego zim (grudzień–marzec) na obszarze Polski. Zmiana faz NAO z w przewadze ujemnych na w przewadze dodatnie, jaka nastąpiła w latach 1987-1989 spowodowała, że po roku 1989 obserwuje się w Polsce znaczne złagodzenie stopnia ostrości zim.

EN

The article raises the issue of the climate phenomenon of the North Atlantic Oscillation (NAO), and describes its influence on shaping the thermal character of winters (December-March) in Poland. The change of NAO phases from those predominantly negative into the predominantly positive, which took place within the years 1987-1989, caused the reduction in severity of winters after 1989 in Poland.

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An 854-year tree-ring chronology of scots pine for south-west Finland

Helama S., Holopainen J., Timonen M, Mielikainen K

Studia Quaternaria

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2014

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Vol. 31, Nr 1

61--68

EN

A near-millennial tree-ring chronology (AD 1147-2000) is presented for south-west Finland and analyzed using dendroclimatic methods. This is a composite chronology comprising samples both from standing pine trees (Pinus sylvestris L.) and subfossil trunks as recovered from the lake sediments, with a total sample size of 189 tree-ring sample series. The series were dendrochronologically cross-dated to exact calendar years to portray variability in tree-ring widths on inter-annual and longer scales. Although the studied chronology correlates statistically significantly with other long tree-ring width chronologies from Finland over their common period (AD 1520-1993), the south-west chronology did not exhibit similarly strong mid-summer temperature or spring/early-summer precipitation signals in comparison to published chronologies. On the other hand, the south-west chronology showed highest correlations to the North Atlantic Oscillation indices in winter/spring months, this association following a dendroclimatic feature common to pine chronologies over the region and adjacent areas. Paleoclimatic comparison showed that tree-rings had varied similarly to central European spring temperatures. It is postulated that the collected and dated tree-ring material could be studied for wood surface reflectance (blue channel light intensity) and stable isotopes, which both have recently shown to correlate notably well with summer temperatures.

6

NAO Soccer Robots Path Planning Based on Rough Mereology

Przytuła Ł.

Fundamenta Informaticae

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2014

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Vol. 131, nr 2

241--251

EN

Soccer game is a good playground for testing artificial intelligence of robots and methods for spatial reasoning in real conditions. Decision making and path planning are only two of many tasks performed while playing soccer. This paper describes an application of rough mereology introduced by Polkowski and Skowron (1994) for path planning in robotic soccer game. Our path planning method was based on mereological potential fields introduced by Polkowski and Ośmiałowski (2008) and Ośmiałowski (2009) but was redesigned due to conditions of dynamic soccer environment, so an entirely new method was developed.

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Wave Climate in the Gulf of Gdańsk vs. Open Baltic Sea near Lubiatowo, Poland

Różyński G.

Archives of Hydro-Engineering and Environmental Mechanics

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2010

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Vol. 57, nr 2

167-176

EN

The paper analyses long-term variability in the wave climate near Lubiatowo, ca. 15 km east of Łeba harbor, and in the Gulf of Gdańsk, near the Vistula river mouth. The wave climate was reconstructed for the 1958-2001 period by the German Institute for Coastal Research (GKSS). Using basic statistical tools - empirical mean values of significant wave height, estimation of the number of threshold crossings above a prescribed value of that height and conditional empirical probability density functions of wave approach directions - a comparison of wave height at the two locations was executed. A substantial reduction in wave height inside the Gulf (sheltering effect) was measured. Further, the increased storminess over the winter season was estimated for the open sea location. Finally, the analysis of wave approach direction in the open sea location revealed substantial growth in extreme waves from the western sector. Given the geographic configuration of the Gulf and the combined rise in storminess and evolution in extreme wave direction, it can be inferred that the sheltering effect of the Gulf can vary depending on locations within the Gulf. Identification of sheltering patterns in the Gulf emerges as obvious follow-up research. This study could also prove useful in analyses aiming at integrated management of coastal zones in the Gulf, mainly in the implementation of Coastal Protection Law (Apr. 2003), which postulates maintenance of the 2001 shoreline configuration along the entire Polish coast.