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1 Problemy Klimatologii Polarnej

1 2009

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Ciśnienie atmosferyczne w Arktyce w okresie Pierwszego Międzynarodowego Roku Polarnego 1882/83

Przybylak R., Wyszyński P.

Problemy Klimatologii Polarnej

2009

nr 19

99-114

W artykule przedstawiono szczegółową charakterystykę ciśnienia atmosferycznego w Arktyce w okresie trwania Pierwszego Międzynarodowego Roku Polarnego 1882/83, do której wykorzystano cogodzinne obserwacje z 9 stacji reprezentujących większość regionów klimatycznych w Arktyce. Analizą objęto następujące parametry ciśnienia atmosferycznego: średnie dobowe, maksymalne i minimalne wartości dobowe oraz ich ekstrema. Szczegółowo omówiono rozkłady przestrzenne, przebiegi roczne oraz zmienność międzydobową. Uzyskane wyniki porównano ze współczesnymi (1961-1990) warunkami barycznymi. Ponadto zbadano współzależności między ciśnieniem atmosferycznym a innymi elementami meteorologicznymi takimi jak temperatura powietrza i stopień zachmurzenia ogólnego nieba.

The paper describes atmospheric pressure characteristics of the Arctic during the First Interna-tional Year 1882/83 based on hourly data gathered for nine stations representing almost all climatic regions of that area (Figure 1). For the analysis the following parameters have been used: mean daily atmospheric pressure (p, calculated from 24 hourly data), daily maximum (p max) and minimum (p min) pressures (selected from 24 hourly data) and extreme values (p max abs, p min abs). The main focus of the paper is directed to the spatial distribution, annual courses of pressure parameters and day-to-day variability of atmospheric pressure. The historical air pressure data were also compared with modern (1961-1990) data. Furthermore, correlation between atmospheric pressure and other meteorological elements (air temperature and cloudiness) has been examined. The spatial distribution (Table 1 and Figure 2) of atmospheric pressure over the Arctic during the First International Polar Year was similar to modern. The Siberian region and the Canadian Arctic had the highest pressure, while the Norwegian Arctic, and areas around the Baffin Bay, showed the lowest average values. The pressure fields in particular seasons reflected pressure patterns that are known today. In the annual course (Table 1 and Figure 3), the lowest monthly means of air pressure occurred during the months of February or March in the Atlantic Arctic and the region of Baffin Bay. Low pressure was also noted in January. In contrast, maxima in pressure occurred mainly in spring. A greater range of variation of air pressure was observable in wintertime than in summertime. The annual courses were different in Siberian and Pacific regions, where the minimum pressure occurred in June and August respectively, in turn maxima occurred in April and February. However, the extent of variation in pressure in the cool season in the Siberian and Pacific regions corresponded with the results obtained for other regions in the Arctic. Monthly averages of day-to-day variability (Figure 4) in atmospheric pressure across the Arctic, with the exception of the Siberian station Sagastyr, showed a maximum in the wintertime. On the other hand, the lowest variability occurred during the summer months. The atmospheric pressure in the Arctic during the First International Polar Year was, on average, lower by 0.7 hPa than today (Table 2). Positive pressure anomalies occurred during the spring, autumn and summer in the Atlantic sector, whereas in the Canadian region and Alaska negative anomalies dominated in nearly all months. However, the differences between the historical and the modern period were not significant. Pressure anomalies in 90% lies within the two standard deviations (Figure 5) from the multi-annual average of the modern period. In the Arctic in the study period, a slight negative but statistically significant correlation between atmospheric pressure and cloudiness was found (Figure 6). Generally, the increase in pressure caused a decrease in cloudiness. The relationship between atmospheric pressure and air temperature was mixed. The increase or decrease of air temperature was mainly influenced by the atmospheric circulation.