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

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.