Fig 6. Comparison of stable carbon isotope time series with East Atlantic Pattern (EAP) and local wind forcing on the NIS.

(A) Cross Wavelet Transform (XWT) analysis between δ¹³C time series of N. pachyderma and PC2 SLP 20CR over the North Atlantic domain: 2nd principal component from 20th Century sea-level pressure data [84], (i.e. the EAP), (B) Wavelet coherence analysis (WTC) between the two time series. The thick black contour designates the 5% significance level against red noise and the cone of influence where edge effects might distort the picture is shown as a lighter shade; the relative phase relationship is shown as arrows (with anti-phase pointing left), (C) Crossplot between the lowpass filtered N. pachyderma δ¹³C and PC2 SLP time series displaying the anticorrelation between the data; using the Stats Linear Correlation Test from IGOR PRO 6 software. The timeline displays that their antiphase relationship disappears from the 1950s onwards when the Marine Suess effect dominates. (D) Cross Wavelet Transform (XWT) analysis and (E) WTC between δ¹³C time series of N. pachyderma the surface easterly wind component (Vwind) of ERA-20C data of the 20th century from 1900–2010 [87] for winter months (NDJ) from a narrow 3 by 3-degree grid box (65–68 °N, 19–22 °W) North of Iceland over the core location; the relative phase relationship is shown as arrows (with in-phase pointing right), (F) Crossplot between the bandpass filters of N. pachyderma δ¹³C and the surface easterly wind component (Vwind) of ERA-20C data of the 20th century.