Century-Scale Intensity Modulation of Large-Scale Variability in Long Historical Temperature Records

Abstract

arge-scale variability in long historical temperature records around the North Atlantic Ocean is analyzed by means of power spectral density (PSD) analysis and detrended fluctuation analysis (DFA). It is found that the intensity of large-scale variability is changeable with time, and long memory analysis can be used to detect this possible intensity variation quantitatively. By estimating long-term memory (LTM) in subrecords of different time intervals, a century-scale variation of LTM is revealed, which further indicates a century-scale intensity modulation of the large-scale temperature variability. At the beginning of the nineteenth and twentieth centuries, the large-scale variability is more apparent, whereas in the second half of the nineteenth and twentieth centuries the large-scale variability becomes less significant. Considering the importance of large-scale variability, the findings herein suggest a new perspective on the understanding of climatic change.