Ancient Auroral Records Compiled From Korean Historical Books

Abstract

Aurora provides an essential diagnostic to spatial and temporal variations of terrestrial space environment and is also an important proxy of solar and geomagnetic activities. Contemporary auroral observations have just continued for more than half a century. Visual auroral phenomena recorded in historical books provide key clues to understand the solar and geomagnetic activities in the long history prior to modern era. In this study, we compiled a new auroral catalog from ancient Korean historical books, including 2013 auroral records with day‐level resolution from 1012 to 1811 CE, especially for the records searched from the Seungjeongweon Ilgi. The number of auroral records in this new catalog is greatly enlarged compared with previous lists. The occurrence of the aurora in the new catalog is generally consistent with previous data sets. This extended data set provides valuable support for various studies related to solar‐terrestrial space weather and ancient climates in the past millennium.

The 8‐Year Solar Cycle During the Maunder Minimum

“…There exist several frequently used auroral list in the past, which have been created by the community for different purposes and therefore show different emphasis on either origin of ancient books or geographic location or span of time (Dai & Chen, 1980; Hayakawa et al., 2017; Lee et al., 2004; Lockwood & Barnard, 2015; Stephenson & Willis, 2008; Usoskin et al., 2015; Willis et al., 1996, 2007; Yau et al., 1995; Zhang, 1985). In a recent teamwork, we compiled a new auroral catalog from ancient Korean historical books of the Koryo‐Sa, the Choson Wangjo Sillok and the Seungjeongwon Ilgi through automatic retrieval from the digital books with formatted keywords and manual confirmation for each record (Wang et al., 2021). The new catalog contains a considerably greater number of auroral observations than previous lists.…”

“…However, past polar aurora records during the Maunder Minimum did not give a convincing, definitive conclusion about the solar cycle length due to the small sample size. Hence, to explore the periodicity of solar activity during the Maunder Minimum, we concentrated our studies on a particular class of red equatorial auroras compiled from historical books (He et al., 2020; Wang et al., 2021) and found a significant ∼8‐year cycle, providing important clues for future investigation of solar dynamo during the GM.…”

“…The geomagnetic field intensity in the WPA is low enough to allow energetic particles to penetrate deep into the atmosphere and excite dynamic equatorial aurora during storm time, and therefore can be used as a proxy of the solar activity. This kind of auroras during the Maunder Minimum was fortunately observed by the naked eyes of ancient Korean professional astronomers and routinely recorded on daily resolution, from which a large equatorial auroral catalog was compiled (Wang et al., 2021), providing a unique way to investigate solar activity during the Maunder Minimum.…”

Interdecadal to Multidecadal Variability of East Asian Summer Monsoon Over the Past Half Millennium

“…The criteria for proxy selection are (a): The data developer utilized the proxy record to characterize EASM variability; (b) the indicators can capture the EASM variability or precipitation variability; (c) the timespan of the proxy record exceeds 100 years, and it covers the 1880–1998 CE initial calculation period; (d) the temporal resolution of the proxy record is less than 10 years or better. We screened 23 proxy records including 2 tree ring width chronologies (Sun et al., 2021; Yang et al., 2014) and 10 tree ring δ 18 O chronologies (Liu, Cobb, et al., 2017; Liu, Wang, et al., 2019; Nakatsuka et al., 2020; Sano et al., 2012; Seo et al., 2019; Xu, Sano, et al., 2013; Xu, Zheng, et al., 2013; Xu et al., 2015; Xu et al., 2016; Yang et al., 2021), 7 speleothem δ 18 O records (Cai et al., 2010; Hu et al., 2008; Tan et al., 2010, 2018, 2020; Wang et al., 2005; Zhang et al., 2008), and 4 historical documentary records (Ge et al., 2008; Mizukoshi, 1993; Shi, Zhao, et al., 2017; Wang et al., 2021) (Figure 3). The historical documentary records are in the monsoon core area, and the natural proxy records are mainly distributed in the monsoon fringe area.…”

Evaluation of the 900‐Year European Auroral Records With Extreme Value Theory

“…Nowadays, the long‐term solar activity before the telescope age can be reconstructed by tree rings (e.g., Solanki et al., 2004), ice‐core data (Beer et al., 2003; Usoskin et al., 2003) or by studying Sun‐like stars (Wood et al., 2002), but its resultant disturbances in the space environment can only be inferred from the auroral records in historical books. These books are mainly from Europe, China, Korea and Japan, and cover the past two thousand years (e.g., Krivský & Pejml, 1988; Lee et al., 2004; Wang et al., 2021; Yau et al., 1995). Several predecessors have tried to study the long‐term trend of the solar‐terrestrial relationship using the historical auroral records (e.g., Krivský, 1984; Lee et al., 2004; Scafetta & Willson, 2013; Siscoe, 1980; Vázquez et al., 2016; Willis et al., 2005, 2007).…”