Abstract
Annual rings record the intensity of cosmic rays (CRs) that had entered into the Earth’s atmosphere. Several rapid
14
C increases in the past, such as the 775 CE and 994CE
14
C spikes, have ...been reported to originate from extreme solar proton events (SPEs). Another rapid
14
C increase, also known as the ca. 660 BCE event in German oak tree rings as well as increases of
10
Be and
36
Cl in ice cores, was presumed similar to the 775 CE event; however, as the
14
C increase of approximately 10‰ in 660 BCE had taken a rather longer rise time of 3–4 years as compared to that of the 775 CE event, the occurrence could not be simply associated to an extreme SPE. In this study, to elucidate the rapid increase in
14
C concentrations in tree rings around 660 BCE, we have precisely measured the
14
C concentrations of earlywoods and latewoods inside the annual rings of Japanese cedar for the period 669–633 BCE. Based on the feature of
14
C production rate calculated from the fine measured profile of the
14
C concentrations, we found that the
14
C rapid increase occurred within 665–663.5 BCE, and that duration of
14
C production describing the event is distributed from one month to 41 months. The possibility of occurrence of consecutive SPEs over up to three years is offered.
The Sun exhibits centennial-scale activity variations and sometimes encounters grand solar minimum when solar activity becomes extremely weak and sunspots disappear for several decades. Such an ...extreme weakening of solar activity could cause severe climate, causing massive reductions in crop yields in some regions. During the past decade, the Sun's activity has tended to decline, raising concerns that the Sun might be heading for the next grand minimum. However, we still have an underdeveloped understanding of solar dynamo mechanisms and hence precise prediction of near-future solar activity is not attained. Here we show that the 11-year solar cycles were significantly lengthened before the onset of the Maunder Minimum (1645-1715 CE) based on unprecedentedly high-precision data of carbon-14 content in tree rings. It implies that flow speed in the convection zone is an essential parameter to determine long-term solar activity variations. We find that a 16 year-long cycle had occurred three solar cycles before the onset of prolonged sunspot disappearance, suggesting a longer-than-expected preparatory period for the grand minimum. As the Sun has shown a tendency of cycle lengthening since Solar Cycle 23 (1996-2008 CE), the behavior of Solar Cycle 25 can be critically important to the later solar activity.
Understanding the temporal variation of cosmic radiation and solar activity during the Holocene is essential for studies of the solar-terrestrial relationship. Cosmic-ray produced radionuclides, such ...as 10Be and 14C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia. Although records from different archives basically agree, they also show some deviations during certain periods. So far most reconstructions were based on only one single radionuclide record, which makes detection and correction of these deviations impossible. Here we combine different 10Be ice core records from Greenland and Antarctica with the global 14C tree ring record using principal component analysis. This approach is only possible due to a new high-resolution 10Be record from Dronning Maud Land obtained within the European Project for Ice Coring in Antarctica in Antarctica. The new cosmic radiation record enables us to derive total solar irradiance, which is then used as a proxy of solar activity to identify the solar imprint in an Asian climate record. Though generally the agreement between solar forcing and Asian climate is good, there are also periods without any coherence, pointing to other forcings like volcanoes and greenhouse gases and their corresponding feedbacks. The newly derived records have the potential to improve our understanding of the solar dynamics and to quantify the solar influence on climate.
Carbon‐14 in tree rings have suggested there had been multiple extreme solar proton events (SPEs) in the past. While the largest events such as in 774–775 CE can be significantly detected by the ...typical precision of accelerator mass spectrometry, smaller but possibly more frequent events have been difficult to be detected. Thus, the frequency or any characteristics of such relatively smaller events are still largely unknown. In this paper, we report that large SPEs had occurred in 1261–1262, 1268–1269, and 1279–1280 CE before the onset of the Wolf minimum based on high‐precision carbon‐14 analyses. It is suggested that they had occurred at the maximum and the declining phase of solar cycles, and that they had occurred during the transition time of solar activity into a deep minimum. We propose that this episode may provide a unique opportunity to elucidate a potential interaction between the solar dynamo and extreme solar flares.
Plain Language Summary
The Sun is a magnetically active star and occasionally cause intense bursts that sometimes accompany the ejection of energetic protons, described as the solar proton events. In this paper, we report that there were three intense solar proton events in the thirteenth century, just before the onset of the Wolf grand minimum. We propose that these events may be related to the weakening of solar activity during that time.
Key Points
Multiple abrupt increases in carbon‐14 content were found during the transition time of solar activity into the grand minimum state
They occurred at solar activity maximum or at the declining phase of solar cycles, suggesting that they originate from solar proton events
The Wolf minimum may provide a unique opportunity to potentially deepen the understanding of the solar dynamo
In 2009, Yamagata University installed a compact 14C accelerator mass spectrometry (YU-AMS) system and an automated graphitization line. The YU-AMS system is based on a 0.5 MV pelletron accelerator ...(1.5SDH-1) developed by National Electrostatics Corporation (NEC). A second automated graphitization line and an additional ion source of the YU-AMS system were installed in 2014. Approximately 2,000 samples have been measured per year using the system since 2010. The long-term stability of the system from 2010 to 2021 was assessed by measuring the IAEA-C6 and IAEA-C7 standard samples graphitized by the automated graphitization line.
The 10Be record in laminated travertines is a potential proxy for reconstructing past solar activity down to the annual scale; however, correcting for the potential influence of climatic or ...environmental variations remains challenging. Here, we present an annually resolved 10Be record using travertines from Baishuitai, China, covering the period from 1510 to 1701 CE, along with environmental proxies, to evaluate climatic influences and implement corrections to accurately reconstruct solar activity. We demonstrate that the 10Be deposition in travertines exhibits two environmental impacts: the transport efficiency of atmospheric 10Be into travertine and the additional 10Be inflow from overland flow associated with rainfall. We show that these impacts can be corrected based on iron and potassium contents. The resulting corrected record agrees with ice‐core and tree‐ring records, demonstrating the feasibility of using such carbonate sediment 10Be records to reconstruct past solar activity.
Plain Language Summary
The travertine 10Be record has great potential as a proxy for high‐resolution reconstruction of past solar activity; however, the methodology for correcting the potential influence of climatic or environmental variations has not been fully established. This study presents a new high‐precision annual 10Be record using travertines from Baishuitai, China, covering the period 1510–1701 CE, together with records of environmental proxies, allowing us to evaluate the climatic influences and establish a methodology for correcting them to facilitate accurate solar activity reconstruction. We find that there are two environmental impacts on the deposition of 10Be in travertine: one is the transport efficiency of atmospheric 10Be into travertine, and the other is the additional 10Be inflow from the runoff following rainfall events, and we use iron (Fe) and potassium (K) contents to correct these impacts. The corrected travertine 10Be record exhibits good agreement with ice‐core 10Be and tree‐ring 14C records, supporting that the 10Be record in Baishuitai travertine reliably reflects the atmospheric radionuclide production rate as regulated by solar activity. This result demonstrates the feasibility of using such carbonate sediment 10Be records to reconstruct annual solar activity and suggests the possibility of extending the annual records further back in time than previously obtained.
Key Points
A high‐precision annual record of travertine 10Be from 1510 to 1701 CE was obtained to assess its potential as a proxy for solar activity
Climatological and environmental impacts on 10Be deposition were found to be correctable based on the content of trace elements
The travertine 10Be record corrected for climatological impacts reasonably preserves the decadal and centennial‐scale solar cycles
Ice-rafting evidence for a “1500-year cycle” sparked considerable debate on millennial-scale climate change and the role of solar variability. Here, we reinterpret the last 70,000 years of the ...subpolar North Atlantic record, focusing on classic DSDP Site 609, in the context of newly available raw data, the latest radiocarbon calibration (Marine09) and ice core chronology (GICC05), and a wider range of statistical methodologies. A ∼1500-year oscillation is primarily limited to the short glacial Stage 4, the age of which is derived solely from an ice flow model (ss09sea), subject to uncertainty, and offset most from the original chronology. Results from the most well-dated, younger interval suggest that the original 1500 ± 500 year cycle may actually be an admixture of the ∼1000 and ∼2000 cycles that are observed within the Holocene at multiple locations. In Holocene sections these variations are coherent with 14C and 10Be estimates of solar variability. Our new results suggest that the “1500-year cycle” may be a transient phenomenon whose origin could be due, for example, to ice sheet boundary conditions for the interval in which it is observed. We therefore question whether it is necessary to invoke such exotic explanations as heterodyne frequencies or combination tones to explain a phenomenon of such fleeting occurrence that is potentially an artifact of arithmetic averaging.
► The last glacial chronology of DSDP Site 609 is updated to Marine09 and GICC05. ► Hematite stained grain cycles occur primarily at 1000- and 2000-year intervals. ► Variability is consistent with Holocene cosmogenic nuclide oscillations. ► 1500 is likely an artifact of arithmetic averaging with little statistical justification.
Frequent consumption of a diet high in fat and sucrose contributes to lifestyle-related diseases. However, limited information is available regarding the short-term effects of such a diet on the ...onset of obesity-associated metabolic abnormalities.
Male C57BL/6 J mice were divided into two groups and fed a standard chow diet (control group) or a high fat-high sucrose diet containing 21% fat and 34% sucrose (HF-HS diet group) for 2 or 4 weeks.
The HF-HS diet significantly induced body weight gain beginning at week 1 and similarly increased mesenteric white adipose tissue weight and plasma insulin levels at weeks 2 and 4. Plasma resistin levels were notably elevated after feeding with the HF-HS diet for 4 weeks. Measurement of hepatic triglycerides and Oil Red O staining clearly indicated increased hepatic lipid accumulation in response to the HF-HS diet as early as 2 weeks. Quantitative PCR analysis of liver and white adipose tissue indicated that, starting at week 2, the HF-HS diet upregulated mRNA expression from genes involved in lipid metabolism and inflammation and downregulated genes involved in insulin signalling. Although plasma cholesterol levels were also rapidly increased by the HF-HS diet, no differences were found between the control and HF-HS diet-fed animals in the expression of key genes involved in cholesterol biosynthesis.
Our study demonstrates that the rapid onset of hepatosteatosis, adipose tissue hypertrophy and hyperinsulinemia by ingestion of a diet high in fat and sucrose may possibly be due to the rapid response of lipogenic, insulin signalling and inflammatory genes.
A significant carbon-14 enhancement has recently been found in tree rings for the year 994, suggesting an extremely strong and brief cosmic ray flux event. The origin of this particular cosmic ray ...event has not been confirmed, but one possibility is that it might be of solar origin. Contemporary historical records of low-latitude auroras can be used as supporting evidence of intense solar activity around that time. We investigate previously reported as well as new records that have been found in contemporary observations from the 990s to determine potential auroras. Records of potential red auroras in late 992 and early 993 were found around the world,
i.e.
in the Korean Peninsula, Saxonian cities in modern Germany, and the Island of Ireland, suggesting the occurrence of an intense geomagnetic storm driven by solar activity.
Abstract
A magnetic storm around 1859 September 2, caused by a so-called Carrington flare, was the most intense in the history of modern scientific observations, and hence is considered to be a ...benchmark event concerning space weather. The magnetic storm caused worldwide observations of auroras, even at very low latitudes, such as Hawaii, Panama, or Santiago. Available magnetic-field measurements at Bombay, India, showed two peaks: the main was the Carrington event, which occurred in day time in East Asia; a second storm after the Carrington event occurred at night in East Asia. In this paper, we present results from surveys of aurora records in East Asia, which provide new information concerning the aurora activity of this important event. We found some new East Asian records of low-latitude aurora observations caused by a storm which occurred after the Carrington event. The size of the aurora belt of the second peak of the Carrington magnetic storm was even wider than that of usual low-latitude aurora events.
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