Solar variability between 650 CE and 1900 - Novel insights from a global compilation of new and existing high-resolution 14C records. (15th September 2022)

• Record Type: Journal Article
• Authors: Kaiser Kudsk, Sabrina Gjødvad; Knudsen, Mads Faurschou; Karoff, Christoffer; Baittinger, Claudia; Misios, Stergios; Olsen, Jesper
• Is Part Of: Quaternary science reviews. Volume 292(2022)
• Publication Date: 2022-09-15
• Subjects: Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2022.107617
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: This study investigates solar variability between 650 CE and 1900 based on new and published 14 C records with a time resolution of two years or higher. The new high-resolution 14 C data presented here are derived from Danish oak and span the period 1058–1250 CE. We determine the durations of past solar minima and periods with moderate solar activity from the solar modulation potential calculated using a carbon-box model with the high-resolution 14 C records as input. The observed intervals of solar minima and intermittent periods with moderate activity levels suggest that a Maunder-type minimum occurred in 656–707 CE. We tentatively propose to name this minimum the Horrebow Minimum after Christian Horrebow, an early Danish astronomer who studied the occurrence of sunspots and was the first to propose that they follow a cyclic behaviour. Changes in amplitude and cycle length of the 11-year solar cycle are investigated by bandpass filtering 23 individual 14 C records. The filtered 14 C data indicate that the length of the 11-year solar cycle may be prolonged before the onset of the Oort, Maunder, and Spörer minima. The amplitude of the 11-year solar cycle associated with solar minima and periods with moderate solar activity between 650 CE and 1900 is estimated to 1.1‰. A two-sample Kolmogorov-Smirnov goodness-of-fit test indicates that there is no significant difference between the amplitude distribution of 11-year solar cycles during solar minima and periods of moderate solar activity. A review of the high-resolution 14 C records encompassing the near-Earth supernova events that occurred in 1006 CE, 1054, 1181, 1572, and 1604 suggests that these events were not accompanied by distinct changes in the 14 C production rate. Nonetheless, an unusual increase of c. 10‰ in Δ 14 C between 1048 CE and 1055 is observed and discussed. Highlights: Solar variability between 650 CE and 1900 is investigated using all available high-resolution 14 C records. An unnamed solar minimum has been detected between 656–707 CE. The name Horrebow Minimum is proposed for this minimum. The cycle length of the 11-year solar cycle was generally longer before the onset of the Oort, Maunder, and Spörer minima. The amplitude of the 11-year solar cycle during solar minima and periods with moderate activity is estimated to 1.1‰ in Δ 14 C. Excursions linked to supernovas are not observed, but an increase of ca. 10‰ in Δ 14 C is found between 1048 CE and 1055.