Fig. 5: Glacial–interglacial sea ice variability and periodicity–variance spectrum of sea ice extent in the Labrador Sea (Lr), Irminger–Iceland basin (Ir–Ic), and Central North Pacific (CNP) sectors.
From: Northern Hemisphere sea ice variability in a transient CGCM simulation of the past 2.6 Ma
The first EOF of sea ice explains 59.7%, 62.9%, and 55.6% of total variance during the post-MPT, MPT, and pre-MPT periods, respectively. The (a) post-MPT, (b) MPT, and (c) pre-MPT periods show detrended sea ice concentration regressed onto the normalized first Principal Component (PC1) (units are in percentage of sea ice concentration). a Dashed boxes demarcate the Lr, Ir–Ic, and CNP regions. Green and blue dots indicate the locations of sea ice records, i.e., core HLY0503-06JPC (HLY-6) (78° 17.6290´ N, 176° 59.1690´ W; 800 m water depth) and MD01-2414 (53° 11.77´ N, 149° 34.80´ E; 1123 m water depth), respectively. a–c Solid black lines represent the sea ice extent boundary, and purple lines represent the perennial sea ice boundary. d–f The periodicity–variance spectrum of sea ice extent in the Lr (40° N–70° N, 80° W–40° W) and Ir–Ic (55° N–70° N, 40° W–25° E) regions are shown in black and blue lines, respectively. g–i The periodicity–variance spectrum of sea ice extent in the CNP (40° N–60° N, 145° E–160° W) region is shown in green lines. Orange (red) lines indicate the red noise with a 95% confidence interval for the sea ice extent in the Ir–Ic region (Lr and CNP regions).
