Slow Quasi Periodical Oscillations in North Atlantic-Arctic-North Pacific Climate System

Lead Author Oleg, Pokrovsky
Institution Contact Russian State Hydrometeorological University
Theme Theme 1: Vulnerability of Arctic Environments
Session Name 1.1 Climate Change and Environmental Management in the Arctic
Datetime Wed, Sep 14, 2016 01:00 PM - 01:20 PM
Presentation Type Oral
Abstract text A coherence between the oscillations responded to various climate system components was evaluated. The ocean is a principal climate component as it is the major heat container on the Earth. The climate fluctuations of the Atlantic Multidecadal Oscillation (AMO) are most evident in the North Atlantic and take roughly 60-80 years to complete. The studies of paleoclimate proxies have shown that oscillations similar to those observed instrumentally have been occurring for at least the last millennium. In the 20th century, the climate oscillations of the AMO have alternately camouflaged and exaggerated the greenhouse warming, and made attribution of global warming more difficult to ascertain. The data sets of the ice extents in the Russian marginal seas for 1900-1999 have been prepared in the Russian AARI. Our smoothing technique allows us to filter out the high frequency components presented in original time series and to reveal a 60-year AMO cycle in a more transparent mode. The AMO wavelet power spectrum demonstrates very strong anomaly area corresponding to a cycle of about 60-70 years, confirming the result based on the AMO series smoothing. Moreover, a statistical analysis showed the 60-year cycle to be a significant phenomenon at the 95% probability level. A smoothed ice extent curve for the Barents and Kara Sea September monthly data demonstrates slow multi-decadal oscillations similar to AMO, but opposite in phase. Wavelet analysis exhibits a power spectrum structure similar to those for AMO. The Pacific Decadal Oscillation (PDO) is defined as the leading principal component (the first empirical orthogonal function) of North Pacific monthly sea surface temperature (SST) variability north of 20° N for the period started from 1900. The PDO is detected as warm or cool surface waters in the Pacific Ocean. During a "warm", or "positive", phase, the west Pacific becomes cool and part of the eastern ocean warms; during a "cool" or "negative" phase, the opposite pattern occurs. It turned out that there is strong coherence between the PDO and ice extent in Chukcha Sea. Physical mechanism is based on wind impact of atmospheric circulation regime on ice extent in Pacific sector of Arctic generated by the SST anomalies in Northern Pacific. This relationship was confirmed by both techniques: smoothing and wavelet analysis. The 60-year cycle in PDO was revealed. The AMO phase delay with account to the PDO for 17-19 years. Similar is valid for ice extent in Atlantic and Pacific sectors of Arctic.
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