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Uwarunkowania klimatyczne aktywności geomorficznej, Wyspa Króla Jerzego, Szetlandy Południowe

Zwoliński Z.

Problemy Klimatologii Polarnej

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2002

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nr 12

33-63

EN

The paper presents the proposal of a method for an indirect evaluation of geomorphic activity on ice-free areas on King George Island (South Shetlands, West Antarctica) through analysis of climatic conditions affecting the mobility of mineral matter. It was assumed that weather conditions affected the movement of mineral matter, which in turn determined geomorphic activity on ice-free areas, which currently occupy over 25 km2 of Admiralty Bay. On the basis of encoded values of six variables: air temperature, wind speed, rainfall, sunshine, ground temperature, and thickness of snow cover, diurnal types of the efficiency of mineral matter circulation were determined which were then clustered using the k-means method. After the cumulation of results for 7-day periods, a total of 59 homogeneous periods were obtained characterised by diurnal types of geomorphic activity (1, 2 and 3) in the observation period from April 10, 1990 to January 13, 1994. The summer season is a period with a high efficiency of mineral matter circulation and geomorphic activity, while winter time is one with a low efficiency of mineral matter circulation and geomorphic activity. Periods with an average efficiency of mineral matter circulation and geomorphic activity correspond to ascending and descending transition times. It is possible to associate the descending period with the autumn season in the temperate zone, while the ascending period, with spring-time.

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Przebieg wartości wskaźnika oceanizmu na Szetlandach Południowych według zweryfikowanych danych połączonego ciągu Deception-Bellingshausen (1944-2000)

Styszyńska A., Zblewski S.

Problemy Klimatologii Polarnej

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2002

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nr 12

21-32

EN

This article presents the characteristic of the course of oceanicity index (Oc) in the region of the South Shetlands and its correlation with ENSO. The research made use of reconstructed by Lagun and Marshall (2001) series of monthly air temperatures at Bellingshausen station (1947-2000). The values of Oc have been calculated both for a calendar and hydrologic years (May - April) with a formulae given by Marsz (1995). Series of Southern Oscillation indexes (SOI) obtained from CRU has been used to examine correlation between Oc and ENSO. Periods of smaller and greater changes in Oc index were observed to take place one following another in the said period (Fig. 1) and a good proportion of the years was marked by ultraoceanicity. A posotive trend appearing in the series turned to be not statistically significant (Fig. 3). The analysis showed 2-year and 6-year periodiciy in the series of Oc index. Correlation between oceanicity index and mean annual air temperature (Fig. 2) and minimum temperature is characterised by high statistical significance. The fact that most significant correlation occurs in winter may prove that changes in ice condition have great influence on the increase in the frequency of occurrence of fresh sea air masses. The obtained results point to a tendency that the increase in air temperature in the region of the South Shetlands and the northern coast of the Antarctic Peninsula is followed by the increase in the transport of heat from the ocean to the atmosphere, represented by the increase in oceanicity index. At this stage we obtain quite paradoxical picture, i.e. the increase in the transfer of heat from the surface of the ocean should be accompanied by great rise in air temperature in winter, that is in the period when the intensity of heat transfer from the ocean to the atmosphere reaches greatest values. However, the analysis of trends indicated that the greatest rise in temperature was observed in the warmest month and in summer temperatures, that is in the periods when the heat transfer from the ocean to the atmosphere was least intensive. This means, that a possible cause ? effect sequence relating the increase in air temperature to the intensity of ocean influence observed in this area must be more comlicated than it is usually observed. Quite clear correlations may by noted here, although occurring with a long, 2-year time shift between the Oc and SOI. Such a great time shift suggests that the correlation between those variables cannot by governed by direct atmospheric circulation but there must be an in direct inertion linking element that retards the effect of temperature increase. The only possible link of this type ocean. The mechanisms that cause the shift of the maximum increase in the transfer of heat from the ocean to the air in winter to the increase in air temperature in summer are not clear. The co-author research results obtained so far seem to indicate that the mechanism responsible for the shift may be attributed to large scale changes in sea surface temperature reflected in changes in sea ice cover extent and its concentration.

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Zjawiska lodowe na Zatoce Admiralicji w roku 1999 (Wyspa Króla Jerzego, Szetlandy Południowe)

Zblewski S.

Problemy Klimatologii Polarnej

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2001

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nr 11

113-120

EN

In 1999 hydrometeorological observations were carried out at H. Arctowski Station. Ice phenomena in the Admiralty Bay and in the visible neighbouring area of the Bransfield Strait were, among others, the subject of these observations. The Admiralty Bay is a typical fjord and is the biggest bay in the Southern Shetlands archipelago, covering 122.08 km2. Winter ice cover formation of this area varies in different years. Once every 4-5 years the waters of the Bay do not freeze and the ice observed there originates from the Bransfield Strait. During the whole year glacial ice (brash ice, growlers, bergy bits and icebergs) originating from local sources and from other sea areas can be observed in the Admiralty Bay. In 1999 the process of the ice cover formation was characterised by variability both in time and space. During the observational period floating ice formed ice fields of different shapes and concentration. Brash ice and growlers often covered the weatter shore during high tidal waters. The icebergs in the said period are mainly observed at the entrance of the Bay (in the region of the Syrezol Rocks) less frequently inside the Bay. They usually drifted in the axial part of the Bay hardly ever reaching its central part. The autochthonous sea ice formed only near the shore and during the whole year it was the inflowing ice which was predominant. First forms of new ice in the waters of the Admiralty Bay occurred in the second decade of June. These forms were initial stage forms (frazil ice and grease ice) which never changed into more advanced form of sea ice. At the end of June the process of ice inflow from the Bransfield Strait started. The allochthonous ice reached mainly the axial and central parts of the Bay, however there were few cases noted in which the ice reached the auxiliary bays. The observations showed that the character of the main features of the winter sea ice cover of the Admiralty Bay was predominantly influenced by wind and ice conditions of the Bransfield Strait. In 1999 the Admiralty Bay was not covered by consolidated ice but by drifting ice which changed its position and edge very quickly. The course of ice phenomena in winter season 1999 had a mild character and according to Kruszewski's categories (1999) defining the ice conditions in the Admiralty Bay may be classed as number one.

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Procesy deglacjacji na obszarze SSSI No. 8 i ich uwarunkowania klimatyczne oraz hydrologiczne (Zatoka Admiracji, Wyspa Króla Jerzego, Szetlandy Południowe)

Battke Z., Marsz A. A., Pudełko R.

Problemy Klimatologii Polarnej

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2001

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nr 11

121-135

EN

This work deals with the processes of deglaciation occurring in the region of SSSI No 8 (Site of Special Scientific Interests No 8) located on the western coast of the in the vicinity of Polish H. Arctowski Station over the period 1979-1999. The location of the SSSI is shown in Fig. 1. The basis of this work is comparison between the category of the surface of the area on the charts from 1979 (Furmańczyk & Marsz, 1980) and on the chart from 1986 (Battke, 1990) and the ground measurements carried out in that area in 1999 (Battke & Pudełko, unpubl.). The categories of area were computed on maps with the help of a planimeter: - glaciated areas, - non-glaciated areas (formed by mineral grounds), - sea areas. The accuracy of total measurements of the area is not lower than about 0.2 km2. The results of cartometric measurements are given in Table 1. Over the period 1979-1999 the area of SSSI decreased by 0.86 km2 as an effect of regression of icy cliffs both of Ecology and Baranowski Glaciers and due to accompanied abrasion process. At the same time the glaciated area within the borders of SSSI decreased by 6.93 km2 and the ice free area increased by 6.08 km2. In this way the mean rate of deglaciation of the 21-year period reaches about 0.33 km2 per year. Over the 21-year period the ice free area within the borders of SSSI incresed three times (from 2.98 km2 to 9.06 km2) which results in various consequences on the physico-geographical and biological prosesses in the region of the Admiralty Bay. In the period 1978-1986 the processes of deglaciation observed north of SSSI in the region of Ecology Glacier were faster than in other regions. Over the period 1986-1999 much faster decrease in the glaciated area was noted in the south of the area, in the region of Baranowski Glacier and Tower Glacier spatial changes are presented in Fig. 2. The analysis of reasons having influence on so advance processes of deglaciation indicated to two factors i.e. climatic and hydrological that are both responsible for the process. Over the period 1978-1998 in region of the Admiralty Bay the increase in air temperature during the Antarctic summer (period December - February; trend +0.022°C/year, statistically not significant) was noted. At the same time the period in which ablation was observed (warmer November and March) was longer. The annual sums of precipitation in the same period indicate to the presence of statistically significant negative trend (-5.7 mm/year, p < 0.005). This resulted in the change in the glacier mass balance at the level 2 m. above sea level: from -115 g/cm2/year in 1979 to -146 g/cm2/year in 1998 (Fig. 3). The evaluated trend of change in mass balance is -1.56 g/cm2/year and is not statistically significant. The period during which sea ice cover is not observed also lasts longer and the ice conditions there became visibly milder. This enables the thermal abrasion to last longer and causes more active regression of ice cliffs. On the shore of the Bransfield Strait, between the Admiralty Bay and the Maxwell Bay entrance a deep cove was formed in the ice coast over the period 1985-1988. This resulted in the increase in inclination of the southern slopes of ice forming the Warszawa Ice cap and forced the volume of ice flowing towards the Bransfield Strait to increase. In this way the volume of ice flowing down the Warszawa Ice Cap eastward, to SSSI No. 8 area, decreased. The explanation of reasons responsible for the ice conditions becoming milder can be found in large scale changes in sea surface temperature of the Southern Ocean of the sea area located West of the Antarctic Peninsula (a strong positive trend SST is marked in the period from October to January; in December +0.058°C/year) and in changes in atmospheric circulation. Both these factors, i.e. the increase in the negative values of the ice masses balance and the decrease in the volume of ice flowing down on the SSSI No. 8 area act in the same direction, causing that the deglaciation process in that region occurs in an exceptionally intensive way. Due to such great intensity of the deglaciation processes occurring on the surface of SSSI in that area, this area can be regarded as a unique object of ecological and environmental research.

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Ujemny trend rocznych sum opadowych na Stacji im. H. Arctowskiego (Wyspa Króla Jerzego, Szetlandy Pd., Antarktyka Zach.)

Marsz A. A.

Problemy Klimatologii Polarnej

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1998

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nr 8

63--77

EN

The paper treats variabiliry of annual precipitation sum registred at the Arctowski Station for the 1978-1996 time period. The annual sum of precipitation show a big variability, its to possible to distinguish three periods in their course. For the period 1978-1985 mean annua1 precipitation sum amounted 560 mm (δn = 26 mm), for the next period (1986-1989) precipitation sum was characterised by a very strong variability (min = 377, max = 630 mm) mean precipitation sum amounted 472 mm,where δn = 95.4 mm. For the last, third period (1990-1996) mean precipitation sum amounted 456 mm (o n = 26.1 mm) (tab. l, fig. 1). Occurrence of strong periodicty every 6.0, 2.0, 4.50, 2.57 and 9.0 years has been found for the course of annual precipitation sum (fig. 2). Also, the spectrum analysis of a course of monthly precipitation sum in March (maximum of precipitation) and August (minimum of precipitation) has been led. Analysis showed the existence strong common periodicity (for annual and month sum: maximum and minimum) every 2.00, 3.60 and 6.00 years. Analysis of amplitudes and phases of periodicity do not explain the occurrence of so big variability of observed precipitation sum. The strong negative trend of annual precipitation sum, significant from the statistic point of view occurs here (fig. 3, formula l). Negative trends were also found in: the course of mean monthly precipitation sum for 8 from 12 monts of a year (the strongest and significant in February), in the course of number of days with measurable precipitation, in the mean annual twenty-four-hours precipitation sum. The negative trend of precipitation sum at Arctowski Station is not conformable to signalised (Ackley S., Bentley C., Foldvik A., Clarke A., King J, Priddle J. 1996.) positive trend of precipitation sum, which appears on the west coast of the Antarctic Peninsula. The examination of relation between precipitation sum at the Arctowski Station with walues of SOI shows, that the strongest relations between annual and maximum precipitation sum in a given year appears with one year delay (SOI of the previous year - precipitation of the present year), whereas in case of minimum sum the strongest relation appears with three years defay (tab. 2). The significant relation between monthly precipitation sum at the Arctowski Station and values of SOI appears in January and February (fig. 4, the strongest correlation with values of SOI are the end of winter and spring of the previous year). The negative trend of SOI correspond with the negative annual precipitation sum at the Arctowski Station. The observed environmental results, which confirms decrease of precipitation sum at the Arctowski Station has been shortly discussed (decrease of fields of permanent snow, disapperance of lakes and seasonal streams, drying of seashore terraces, hastening of ablation of glaciers ice from a surrounding glaciers, hastening of deglaciation processes).

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Pokrywa śnieżna w rejonie Stacji H. Arctowskiego (Szetlandy Pd., Antarktyka) w latach 1978-1996

Kejna M., Láska K.

Problemy Klimatologii Polarnej

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1998

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nr 8

79--93

PL

Pokrywa śnieżna jest istotnym czynnikiem klimatotwórczym. Długość jej zalegania oraz jej miąższość wpływają również na wegetację roślinną i przebieg procesów peryglacjalnych w gruncie (Krajewski 1986; Kejna i Laska 1999b). W klimacie subantarktycznym pokrywa śnieżna tworzy się w warunkach ogromnej zmienności pogody. We wszystkich porach roku występują dodatnie i ujemne temperatury powietrza oraz stałe i ciekłe opady atmosferyczne. Silne wiatry przenoszą śnieg, znacznie modyfikując pokrywę śnieżną. Na Stacji H. Arctowskiego (Wyspa Króla Jerzego, Szetlandy Południowe) prowadzono systematyczne pomiary miąższości i czasu zalegania pokrywy śnieżnej w latach 1978-1990 oraz w 1992 i 1996 r. Jednak pokrywie śnieżnej poświęcono tylko niezbyt obszerne akapity w artykułach podsumowujących kolejne wyprawy, np. Nowosielski 1980; Kratke i Wielbińska 1981; Kowalski 1986; Kejna i Laska 1997. Zagadnienie to nie było poruszane nawet w opracowaniach o charakterze monografii klimatu tego obszaru, np. Marsz i Rakusa-Suszczewski 1986; Marsz i Styszyńska 2000. Badania nad zróżnicowaniem przestrzennym miąższości pokrywy śnieżnej w okolicach Stacji H. Arctowskiego oraz na Lodowcu Ekologii prowadzono jedynie w 1991 r. (Gonera i Rachlewicz 1997) oraz w 1996 r. (Caputa i in. 1997).

EN

The snow cover was investigated at the Arctowski Station (King George Island, Antarctic) in the period 1978-1996. During the 20th Polish Antarctic Expedition in 1996 the snow cover was measured in 32 places on the Sile of Special Scientific Interest No. 8 in the vicinity of the Arctowski Station (King George Island, Antarctic). On the King George Island the snow cover can occur around the year. In the summer months the snow cover is unstable. On the average 230 days with snow cover occurred at the Arctowski Station. The permanent snow cover began at 7th May and ended at 23th November. The mean snow cover thickness in the years 1978-1996 was between 40 to 50 cm, but the maximum reached 131 cm in 1980. The accumulation of snow was disturbed by frequent midwinter thawing and snow drift. In 1996 at the Arctowski Station permanent snow cover was formed on 6 June and stayed till 31 October. It reached its maximal thickness, 73 cm in September. The snow cover on the SSSI No 8 area showed great spatial differentiation. This is the effect not only the different sums of precipitation, but also the redistribution of the snow by wind. On the nonglaciated area the biggest thickness of snow cover was measured in depressions, in the filled up valleys of streams and on the snow patches. Heights and mountain peaks are without snow because of the wind. On the Ecology Glacier in 1996 the thickness of snow cover increased with the altitude. The biggest thickness of snow cover (177 cm) was measured at 165 m above sea level. In summer the snow cover melts, on the glaciers the snow border runs from 150 to 300 m above sea level in dependence on the weather conditions. On the nonglaciated areas the snow stays until the middle of summer in the form of snow patches.