Thermal characterisation of Lake Morskie Oko water in 2007 based on measurements by a gradient thermal probe
The study was undertaken to illustrate a wide range of application of a gradient thermal probe in thermal characterisation of water reservoirs on the example of Lake Morskie Oko whose water temperature has been measured since 2006. For analysis, the data collected in 2007 were chosen because of the least missing data; in this year only the data from 13 days were not recorded. The data permitted analysis of changes in daily mean temperatures of water at particular depths, with the daily means calculated as arithmetic means from 144 measurements made at every 10 minutes. The daily amplitudes of temperatures at particular depths and mean daily amplitudes for particular months were determined, which permitted an assessment of the scale of the temperature amplitude damping with increasing depth. High frequency of temperature reading permitted detection of short-duration anomalies, taking place e.g. over a time span of 10 minutes, or their vertical extent. It has been established that measurement at 2 a.m. is the optimum for determination of the annual mean temperature. The time moments at which the minimum and maximum temperatures are recorded within a day at the surface were identified. Different variants of temporary jump changes in the surface water temperature within the day were analysed. The dynamics of temperature changes from the surface to the bottom of the lake was discussed.
The aim of this study was to gather and summarize bathymetric measurements of Morskie Oko Lake which have been carried out up to now. Apart from the two existing plans from 1909 and 1934, a plan presenting the arrangement of isobaths in 1879 was worked out on the basis of numerical data. Moreover, after field investigation with an echo sounder in 2011, a new bathymetric plan was created. All four plans were used to calculate the basic morphometric parameters of Morskie Oko. Bathygraphic curves were determined from the volume of water found by measuring the areas between consecutive isobaths. The least accurate data come from 1879 while there is a considerable resemblance between the plans dated to 1934 and 2011. In case of the most recent plan, the measurements were for the first time related to the average, multi-annual (1963-2010) water level. Thus, the greatest depth found in 2011 can be regarded as the maximum depth. Further bathymetric studies could help to determine the rate of shallowing of Morskie Oko lake caused by weathered rock material, transported for instance by avalanches.
The paper presents an analysis of water stages in Lake Wielki Staw based on observations by the Institute of Meteorology and Water Management conducted in the years 1968-1979. Water level (low and high) variability was determined in the annual cycle, together with the variability of annual stages in the analysed 12-year period, and their amplitudes. Moreover, water stage variability trends were identified. Due to the vicinity of Lake Morskie Oko, comparisons of water stages in both lakes were performed for the purpose of determining the degree to which water supply (water stages) is affected by local and climatic factors.
Due to its inaccessibility (in winter), Lake Czarny Staw pod Rysami (Black Lake below Mount Rysy) has no series of continuous observations concerning ice phenomena. For the purpose of supplementing knowledge in this scope, ice corings were performed in the years 2010–2015. They permitted the determination of the variability of ice cover thickness on the lake’s surface. A high degree of similarity was determined in the distribution of ice cover thickness in the analysed winters (in contrast to the nearby Lake Morskie Oko). Moreover, a correlation was determined according to which the thicker the snow cover overlying the ice, the thinner the ice cover. It was determined that the mean thickness of the ice cover of Lake Czarny Staw pod Rysami is higher by approximately a dozen cm than that on Lake Morskie Oko located around 200 m lower.
The paper presents an analysis of the ice phenomena on Lake Wielki Staw in the Valley of Five Polish Lakes based on observations of the Institute of Meteorology and Water Management conducted in the years 1971–1979. The dates of commencement and decline of ice phenomena and ice cover and their persistence were determined. For 1978 and 1979, changes in the ice cover were determined, i.e. from development to decline. Due to the close vicinity of Lake Morskie Oko, comparisons were performed in terms of variability of ice phenomena of both of the lakes. The study showed among others that although Lake Wielki Staw is located higher than Lake Morskie Oko by approximately 270 m, ice phenomena on the lake appear on the average 10 days later than in Lake Morskie Oko, and the mean persistence of the ice cover is the same, i.e. it amounts to 167 days.
The character of phenomena related to freezing depends on macroscale factors and mainly on thermal conditions, but local conditions can also be of great importance in shaping the course of these phenomena. Building of ice cover can be substantially different even for neighbouring lakes as a result of different individual features such as, for example, morphometric parameters. In this study the variation in the thickness of ice cover on Lake Samołęskie (29 ha) localised in western Poland, is analysed. According to measurements performed the differences in the thickness of ice cover was significant as it varied from 20 to 33 cm. A characteristic feature was that along the west bank of the lake the ice cover was thinner and its thickness increased towards the east. Analysis of the hydrogeological data revealed that this phenomenon is related to the supply of water to the lake basin by efficient water-carrying formations. The influx of water affects the bottom layer of the ice cover. This effect is aggravated by the fact that the water is supplied under elevated pressure as evidenced by the presence of a polynia of about 10 m in diameter, over the deepest (over 20 metres deep) site in the lake. The polynia is never frozen, even during the coldest winters. The specific features of the lake illustrate the influence of local geological conditions on the character of processes taking place in lakes in general.
Dariusz Wrzesiński, Adam Choiński and Mariusz Ptak
The paper presents the effect of North Atlantic Oscillation of macroscale atmospheric circulation (NAO) on the hydrological conditions of Lake Morskie Oko located at an altitude of 1392.8 m a.s.l. in the highest range of the Carpathians. The paper applied detailed hydrometric information from the years 1971-2010 concerning water level fluctuations, water temperature, terms of the commencement and end of ice phenomena and ice cover, as well as meteorological data concerning air temperature and atmospheric precipitation, and monthly and seasonal NAO indices. The performed analysis suggests that the majority of analysed hydrological characteristics of Lake Morskie Oko was not prone to variability of NAO intensity in its various phases. The situation results from the local conditions, particularly responsible for the course of processes and phenomena in Lake Morskie Oko, simultaneously obscuring the effect of macroscale factors.
Agnieszka Ławniczak, Janina Zbierska, Sylwia Machula and Adam Choiński
Fluvial lakes affect on phosphorus and potassium concentrations in the Samica Stęszewska River
The aim of the study was to evaluate the effect of shallow lakes on reactive, total phosphorus and potassium concentrations in the river water and analyse the effect of changes in water retention in lake on nutrient concentrations in river waters. The study was carried out in the Samica Steszewska River. This is lowland river, which flows through two polymictic lakes. The study site is located in the Wielkopolska Lowland, Central-west Poland. Water samples were collected at depths of 0.5 m below the water surface. Reactive, total phosphorus and potassium were analysed monthly by standard methods. The study was carried out from January to December 1999-2002 (period with high water retention), 2005-2008 (period with low water retention), at four control points. Sites were located at the inflow and outflow of the Samica Stęszewska River into and out of Niepruszewskie and Tomickie Lakes. From 1974 to 2002, Lake Niepruszewskie was regulated at its outlet by a weir. In 2002, the water level was reduced. Changes of water retention in Niepruszewskie Lake influenced water discharge of the Samica Stęszewska River. The results indicate that changes in water retention have significantly influenced water quality in the river, particularly total and reactive phosphorus concentrations; however, this influence was not observed in respect to potassium concentrations. Nutrient concentrations in river strongly depend on water quality of the lake ecosystem and their buffering capacity. Additionally, by improving water quality, increased oxygen concentrations, and decreasing dissolved nutrient concentrations, as well as increased amplitude of water level fluctuations in lakes may increase P-fixation rates in outlet streams.
The paper presents water temperature fluctuations in coastal rivers (Rega, Parsęta, Słupia, Łupawa, Łeba) located in the southern Baltic Sea area in Poland. Based on the available detailed data on daily values of the analysed characteristic in the years 1971-2015, tendencies of changes in the period were determined. It includes an analysis of temperature fluctuations in reference to mean annual and mean monthly values. In all of the five cases, the mean annual temperature showed an increasing tendency. The value of water warming in particular rivers was approximate, and ranged from 0.26 °C∙dec-1 to 0.31°C∙dec-1. At the monthly scale, the highest increase was recorded in April, and amounted to 0.46°C∙dec-1 on average. Water temperature fluctuations were particularly determined by climatic changes, and strongly correlated with air temperature. Local factors characteristic for coastal rivers, i.e. presence of infrastructure of small water power plants and predominance of groundwater alimentation, had a secondary effect on changes in the thermal regime of the analysed rivers.
During field research work an attempt was made to use an infrared camera in alpine conditions without the use of a plane. The images received as thermal pictures are of high value because they show a continuous record of temperature on the whole water surface. The scale of temperature diversity is very high and amounts to approximately 6°C. It is necessary to take photos of this type at short time intervals. It will enable the circulation of waters which results in a change in water temperature to be captured. This research will also allow seasonal changes of water temperature to be seized, for example during summer stagnation, water freezing, destruction of the ice layer and also the influence of the coastal zone on shaping thermal conditions in the zone of coastal waters.