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Combined approach to the analysis of near-surface wind speed tendencies at the Vernadsky Station, West Antarctic Peninsula

Gorbachova Liudmyla, Khrystiuk Borys, Shpyg Vitalii, Pishniak Denys

Meteorology Hydrology and Water Management. Research and Operational Applications

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2024

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Vol. 12, Iss. 2

58--73

EN

In Antarctica, studying the near-surface wind regime is important because its dynamics directly affect the continent’s ice shelves. The nearsurface wind is also important for analyzing global and regional climate. Vernadsky Station has a fairly long observation series of nearsurface wind speed. These data are widely used to research changes, variability, and trends in the near-surface wind regime on the Antarctic Peninsula. The observation series, however, has gaps and incorrect values associated with periodical updates of measurement devices. Thus, the observation data require careful evaluation of homogeneity and stationarity. The objective of this study was to investigate the homogeneity, stationarity, and tendencies of the near-surface wind speed in the area of the Vernadsky Station based on a combined approach using several statistical and graphical methods. The methods’ diverse properties support more robust estimates. Consequently, five statistical tests (standard normal Alexandersson test, Buishand test, Pettitt test, von Neumann relation, and Mann-Kendall test) and three graphical methods (chronological graph, mass curve, and residual mass curve) were employed. Most of the observation series is homogeneous and stationary, except the mean annual and February mean monthly near-surface wind speeds, which display both decreasing and increasing phases in their long-term cyclical fluctuations, which are continuing. Violation of homogeneity and stationarity results from the comparison of different phases of cyclic fluctuations (decrease and increase), which have different statistical characteristics. We show that over the past 20 years at the station, the near-surface wind speed has tended to increase in all months of the year.

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Trends and fluctuations of river ice regimes in the Prypiat Basin, within Ukraine

Gorbachova Liudmyla, Afteniuk Oleksandr, Khrystiuk Borys, Lobodzinskyi Oleksandr

Meteorology Hydrology and Water Management. Research and Operational Applications

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2023

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Vol. 11, Iss. 1

62--75

EN

Information about the formation, destruction, and duration of river ice regimes is especially important for hydropower, shipping, fisheries, etc. Research into modern trends in river ice regimes and their spatial and temporal fluctuations is essential, especially in a changing climate. This study examines the trends and fluctuations of air temperature and ice regimes based on series of observations in the Prypiat River basin within Ukraine. Air temperature data from 17 meteorological stations and ice data from 29 water gauges were analyzed. A complex analytical approach involving statistical and graphical methods was employed. The Mann-Kendall statistical test, mass curve, residual mass curve, and combined graphs were used in the study. In the Prypiat River basin within Ukraine, observations of mean monthly air temperature, ice occurrence, freeze-up, and their duration are homogeneous (quasi-homogeneous) and stationary (quasi-stationary). The quasi-homogeneous and quasi-stationary characteristics are explained by the presence in the observation series of only increasing and decreasing phases of long-term cyclical fluctuations, which are incomplete. The trends of air temperature and ice regime correspond strongly, indicating the defining role of air temperature in the formation of ice occurrence and freeze-up. Since the end of the 1990s, the warming phase of air temperature in the autumn-winter period determines the appearance of ice and freeze-up later in the year. In March, the warming trend in air temperature, which began after 1988, determines the freezeup, break-up, and disappearance of ice earlier in the year. Thus, the duration of ice and freeze-up on the rivers has decreased.

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Changes in extreme temperature indices at the Ukrainian Antarctic Akademik Vernadsky station, 1951-2020

Khrystiuk Borys, Gorbachova Liudmyla, Shpyg Vitalii, Pishniak Denys

Meteorology Hydrology and Water Management. Research and Operational Applications

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2022

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Vol. 10, Iss. 1

95--106

EN

In the late 20th century, warming on the Antarctic Peninsula was most pronounced compared to other parts of Antarctica. However, air temperature showed a significant variability, which has become especially evident in recent decades. Thus, the investigation of air temperature trends on the Antarctic Peninsula is important. This study examines the extreme air temperature at the Ukrainian Antarctic Akademik Vernadsky station, located on Galindez Island, Argentine Islands Archipelago, near the Antarctic Peninsula. For 1951 to 2020, based on the daily air temperature data, the temporal trends of extreme air temperature were analyzed, using 11 extreme temperature indices. Based on linear trend analysis and the Mann-Kendall trend test, the TXn, TNn, TN90p, and TN90p indices showed an upward trend, whereas theFD0, ID0, TN10p, TX10p, and DTR indices showed a downward trend. Among them, annually, FD0, ID0, and TN10p significantly decreased by –0.427 days, –0.452 days, and -0.465%, respectively, whereas TXn and TNn increased by 0.164℃ and 0.201℃, respectively. The indices TXx and TNn showed no statistically significant trends. The average annual difference between TX and TN (index DTR) showed a nonsignificant decreasing trend at –0.029℃ year-1 . Thus, for the period of 1951-2020, the Ukrainian Antarctic Akademik Vernadsky station was subjected to warming.

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Application of the commensurability method for long-term forecasting of the highest summer floods on the Danube River at Bratislava

Khrystiuk Borys, Gorbachova Liudmyla, Pekárová Pavla, Miklánek Pavol

Meteorology Hydrology and Water Management. Research and Operational Applications

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2020

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Vol. 8, Iss. 1

70--76

EN

This paper reports the use of the commensurability method for long-term forecasting of the highest summer floods on the Danube River at Bratislava. Bratislava is the capital of the Slovak Republic, as well as its major administrative and industrial centre. In the past, Bratislava has suffered from dangerous floods. The highest floods have occurred most frequently in the summer. Consequently, long-term forecasting of summer floods on the Danube River at Bratislava has important scientific and practical significance. We used the dates of the highest summer floods for the period 1876-2018, as well as historical information about the highest summer floods that occurred before the beginning of regular hydrometric observations. The commensurability method supports prediction of various natural phenomena, including floods and other dangerous events. It is characterized by the simplicity of the calculations and minimum needs for input information. Four methods of forecasting were used: (1) the calculated value of commensurability; (2) the two-dimensional and three-dimensional graphs of commensurability; (3) the time intervals between floods that have occurred in the past; and (4) the number of commensurability equations with three components. The results indicate that the highest summer floods are likely to occur on the Danube at Bratislava in 2020, 2025, and 2030.

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Estimation of the long-term cyclical fluctuations of snow-rain floods in the Danube basin within Ukraine

Zabolotnia Tetiana, Gorbachova Liudmyla, Khrystiuk Borys

Meteorology Hydrology and Water Management. Research and Operational Applications

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2019

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Vol. 7, Iss. 2

3--11

EN

Floods are a periodic natural phenomenon, often accompanied by negative consequences for the local population and the economy as a whole. Therefore, knowledge of the trends of maximum flow have great practical importance, because it is the basis for planning and designing various hydraulic structures, hydrological forecasting, the mapping of flood risk, etc. In this paper, we analysed the long-term cyclical fluctuations of the maximum flow of snow-rain floods of the Danube basin within Ukraine (5 large rivers, 14 medium and 5 small). The database includes time series (34 gauging stations) of the maximum discharges of the cold period from the beginning of the observations up to 2015. The methodological approaches (developed by Gorbachova) are based on the use of hydro-genetic methods − namely the mass curve, the residual mass curve, and combined graphs. The presented results illustrate that the longterm fluctuations of the maximum flow of snow-rain floods are synchronous at all study gauging stations in the Danube basin within Ukraine, but these fluctuations are not always in the synchronous phase. We found that the maximum flow of snow-rain floods in the Danube basin within Ukraine have four types of long-term fluctuations, each with a different cycle duration.