Structure of Variability of Surface Level Pressure above Arctic for 1958–1997

The weather of the northern countries depends from statement of the atmosphere above the Arctic. We decide to find out the structure of variability of SLP above the Arctic, the synoptic nature of her components and temporal tendency of their changing. The daily SLP fields (2592 grid-points of WCRP database) above the Arctic for 1958-1997 was researched with using method of the Empirical Orthogonal Function (EOF). The basis of the investigations was a annual EOF of SLP for 1958-1997 and the variability of the factors of the EOF decomposition of the daily SLP fields. The next results was received: 1. The meanings of the mean month’s factors for 1958-1997 had a identical character for 8 five-year periods. It gives evidence about a stability of received results. 2. The amount of earliest 6 factors of decomposition describes the meaning of the SLP variability from 80% (August) to 88% (February). 3. The variability of the mean month’s factors allow to determine the nature of given variability. It was very surprisingly that maximum contribution to the total SLP variability carry in not solar radiation (her contribution is a meaning from 17% (September) to 21% (March)) but processes connected with development of the Arctic anti-cyclone (AA). Their contribution is a meaning from 22% (July) to 38% (January). 4. The mean annual factors had a good pronounced temporal tendency for 1958-1997, which could characterize a relaxation of AA with proper consequences for future weather of the northern countries. 5. The variability of the mean month’s meanings for both the factor 1 and factor 2 has a contrary character for spring, summer and autumn that don’t allow to unite the given season’s synoptic processes in the single classification. 6. The repeatability of the blocking’s anti-cyclone penetrations from Europe and Eastern Siberia has a good pronounced contrary periodical character (3-4 year). 7. The restoration of the mean month’s SLP fields using the factors and EOF allowed to determine a synoptic nature of the given factors: - the increase of the factor 1 from –0.9 (October) to 1.7 (April) characterize a intensification of AA (lat.=80.0 and lon.=190.0) and filling in of the cyclone above the Norway sea; - the increase of the factor 2 from –1.2 (August) to 1.6 (January) characterize a Intensification of AA (77.5/190.0) and deepening of the cyclone (72.0/0.0); - the increase of the factor 3 from –0.5 (May) to 0.5 (August) characterize a the relaxation of AA and changing of his center position from 77.5/220 to 75.0/150.0 and , also, deepening of the cyclone and changing of his center position from 75.0/50.0 to 70.0/0.0. The given factor describes the total SLP variability from 12% (January) to 15% (July); - the increase of the factor 4 from –0.4 (October) to 0.5 (February) characterize a small intensification of AA and changing of his center position from 77.0/220.0 to 77.0/160.0 and, also, a small filling in of cyclone without changing of his center position. The given factor describes the total SLP variability from 9% (February) to 11% (July); - the increase of the factor 5 and factor 6 describe a small changing of SLP in the climate cyclone and AA and their position but the amount contribution of given factors to total SLP variability changes from 8.7% (January) to 13.5% (July). Thus, the received results could be useful for understanding of the nature of SLP variability and future temporal tendency of climate changing.