The Sun-Climate Effect: The Winter Gatekeeper Hypothesis (I). The search for a solar signal
Posted on July 31, 2022 by curryja | 64 Comments
by Javier Vinós and Andy May
“Probably no subfield of meteorology has had as much effort devoted to it as the effects of solar variability on weather and climate. And none has had as little to show for the research labor.” Helmut E. Landsberg (1982)
1.1 Introduction
The sun has been identified as the source of climate since the dawn of human intelligence, and consequently the sun was worshipped in many ancient cultures. Large sunspots are visible with the naked eye when the sun is low on the horizon and partially obscured by dust or smoke. Several myths and iconography suggest sunspots were known to ancient cultures from America, Africa, and Asia; however, the first written mention of a sunspot comes from Theophrastus’ De Signis Tespestatum c. 325 BC. This first written record of solar variability was already linked to a climatic effect, as Theophrastus mentions its association to rain. Theophrastus is considered the father of botany and was the student of Aristotle that succeeded him as the head of the Lyceum when Aristotle, teacher of Alexander the Great, had to flee Athens due to anti-Macedonian sentiment. Theophrastus mention in passing of sunspots must have referred to common knowledge from the past, since he lived through the Greek grand solar minimum of 390–310 BC (Usoskin 2017) and it is very unlikely that anybody at that time could have seen a sunspot with their naked eyes. Most naked-eye sunspot observations known to us come from China, where records have been found starting from 165 BC. The oldest known drawing of actual sunspots is from the Chronicon ex chronicis by John of Worcester, dated in the manuscript to December 1128, during the Medieval grand maximum in solar activity.
Aurorae are an atmospheric light phenomenon that results from the interaction of solar wind and the geomagnetic field, usually produced between 10-20° from the geomagnetic poles. Aurora is the Roman goddess of the dawn, sibling of Sol and Luna. Every morning she would open the gates of heaven for the sun to rise and then race across the early morning sky in her chariot to alert of a new day. The name aurora borealis was given to the atmospheric phenomenon by Galileo in 1619, indicating its northern (boreal) direction. Aurorae are occasionally seen in mid-latitudes and rarely in low latitudes, when a geomagnetic storm temporarily enlarges the auroral oval. Aurorae have been observed since antiquity. The first records of aurora appear to be three Assyrian clay tablets c. 660 BC (Hayakawa et al. 2019). The prophet Ezekiel also recorded an aurora c. 593 BC in the Bible, and Aristotle wrote about aurorae in his treatise Meteorologica in 340 BC. However, the association of aurorae to solar activity was impossible to make until the arrival of modern science. Anders Celsius was the first to propose that aurorae were linked to the Earth’s magnetic field in 1733, but the solar link had to wait until the Carrington event of 1859, when the solar flare detected by Richard Carrington and Richard Hodgson that caused a great geomagnetic perturbation was followed by the most intense and lowest latitude reaching aurora in recorded history. Aurorae historic records since antiquity are used, together with naked-eye historic sunspot records, to study past solar activity.
https://judithcurry.com/2022/07/31/the-sun-climate-effect-the-winter-gatekeeper-hypothesis-i-the-search-for-a-solar-signal%ef%bf%bc/#more-28883
