Zmiany prędkości wiatru w rejonie Svalbardu w latach 1948-2008

Praca charakteryzuje prędkości wiatru w oparciu o dane pochodzące z reanaliz NCEP/NCAR. Zmiany prędkości prześledzono w dwunastu punktach gridowych z rejonu Svalbardu. W przebiegu rocznym stwierdzono większe prędkości w miesiącach zimowych i mniejsze latem, przy czym amplituda tych zmian jest ponad dwukrotnie większa w południowej części rozpatrywanego obszaru. W przebiegach wieloletnich (1948-2008) obserwuje się istotny statystycznie wzrost rocznej prędkości wiatru w ośmiu gridach. W ostatnich trzy-dziestu latach wzrost ten przybierał na sile. Największe zmiany odnotowano w rejonie na północ od Svalbardu.

The aim of this work was to analyse the surface wind speed changeability in twelve grids points situated in the vicinity of Svalbard (Fig. 1) Gridded surface data from NCEP Reanalysis Derived data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA from their Web site at http://www. cdc.noaa.gov/ were used for statistical analysis over the period 1948–2008. The highest annual wind speed values (8.0 mźs–1) were noted in the south of area (75°N), the lowest in situated over land grid [80, 20] and in the northern part of area at 82.5°N (5.9-6.0 mźs–1). During the year maximum wind speed were noted in winter months, minimum in June or July in all grid points. The differences between winter and summer values are over two times higher at 75°N than in north (82.5°N) – see Tab. 1., Fig. 2. Maximum difference (3.9 mźs–1) was noted in [75, 10], minimum (1.6 mźs–1) in [82.5, 30] grid point. Differences in wind speed between selected grid points are bigger during winter and smaller in summer. Statistically significant positive trends in annual wind speed values were found in years 1948-2008 in whole area, except at 77.5°N and [80, 20] grid point.. The trend value is the greatest in [82.5, 10] grid (+0.017 mźs–1 per year) – see Tab. 3. At latitudes 75 and 80°N values of linear trend coefficients are lower (from +0.006 to +0.01 mźs–1 per year). In shorter 30-year periods continuous significant increase in wind speed is observed at 82.5°N from 60. to the present. The highest positive trend value was noted in [82.5, 10] grid over the 1978-2008 period (+0.032 mźs–1 per year). During the last 30 years significant positive trends in wind speed are present at latitude 80°N and in grid points [77.5, 20]; [77.5, 30].