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Image : Arctic Ocean Oscillation Index (AOO)


Figure 3 AOO index and circulation regimes. Panels (a) and (b) show typical annual distributions of SLP and surface winds for cyclonic and anticyclonic atmospheric circulation regimes, respectively; red arrows show prevailing cyclone tracks, summarized from panel (c).

(c) Greenland Sea cyclone trajectories for 1949–2002 (this is fig. 2 from Sortenberg and Walsh [2008]).White dots indicate the start of each cyclone trajectory and the white and grey lines show two different paths identified by cluster analysis and well supporting SLP distributions corresponding to circulation regimes shown in (a) and (b), respectively. This means that annual SLP distribution patterns express statistics of cyclone counts—prevailing cyclone trajectories.

(d) 1946–2013 mean wind-forced simulated sea surface height (SSH) distribution.

(e) First EOF mode (48% of the variance) of the annual sea surface height pattern.

(f ) AOO indices. The thick black line depicts the 5-year-running-mean time series of the AOO index derived manually following the approach of Proshutinsky & Johnson [1997] and definition provided above. Positive (blue bars) AOO indices correspond to years with ACCRs and negative (red) bars show cyclonic regimes. Coefficients of the annual first EOF mode of the simulated wind-driven sea surface heights as the 5-year running mean are shown as the blue solid line. GSA years are shown as shaded boxes.

(g) Spectra of the AOO calculated from the timeseries of the detrended annual AOO index from 1946 to 2013 using the Tukey window with band width 0.279 rad yr−1. The vertical blue bar denotes the 95% confidence interval of the peak with corresponding frequency ω =0.551 rad yr−1 (11.4 years).

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Last updated: November 6, 2019
 


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