On the alleged coherence between the global temperature and the sun's movement

TL;DR

This paper critically examines claims of coherence between global temperature variations and the sun's movement, revealing that previous spectral analyses were based on assumptions invalidated by time-frequency analysis, and finds limited coherence only around 15-17 years.

Contribution

It demonstrates that previous claims of temperature-solar coherence are based on flawed spectral assumptions and provides a more accurate analysis showing limited coherence.

Findings

Spectral peaks in temperature data are not time-invariant.

Coherence is only observed around 15-17 years.

Previous claims of coherence at 10-60 years are not supported.

Abstract

It has recently been claimed that there is significant coherence between the spectral peaks of the global temperature series over the last 160 years and those of the speed of the solar center of mass at periods of 10-10.5, 20-21, 30 and 60-62 years. Here it is shown that these claims are based on a comparison between spectral peaks in spectral estimates that assume that the global temperature data contains time-invariant spectral lines. However, time-frequency analysis using both windowed periodograms and the maximum entropy method shows that this is not the case. An estimate of the magnitude squared coherence shows instead that under certain conditions only coherence at a period of 15-17 years can be found in the data. As this result builds on a low number of independent averages and also is unwarranted from any physical model it is doubtful whether it is significant.