MPE webinars – week 10: Tommaso Alberti – Nonlinear decomposition of the Pleistocene climate …

MPE: Analysis and Modelling – week 10, 10th July 2020

Tommaso Alberti (INAF-IAPS)

“Nonlinear decomposition of the Pleistocene climate record and the response to orbital forcing”

We use the Hilbert-Huang transform to investigate the climate variability across the Pleistocene and to describe the glacial cycle shift from the ”41-kyr world” to the ”100-kyr world” through the mid-pleistocene transition (MPT). We find that the climate record is decomposed into only 10 empirical modes, the first mode representing the high frequency climatic noise, and the next eight grouped into three groups of modes with time scales in the ranges around 13-51 kyr, 87-222 kyr and 340-837 kyr, together with a residual trend over the 2 Myr period. By summing the empirical modes in each group, we obtain three climate components R 41 (t), R 100 (t) and R L (t) which we
suggest to be loosely associated with the astronomical parameters representing precession and obliquity, the eccentricity, and long geological time scales. By the Hilbert spectral analysis we obtain the time varying amplitudes showing significant variations across the Pleistocene and characterizing the MPT. The correlation results and the spectral coherence suggest that the MPT is characterized by changes in the amplitude of the different components and not in their frequency.