A5067454009- Solar and Space Plasma Dynamics
- Geology and Paleoclimatology Research
- Geomagnetism and Paleomagnetism Studies
- Archaeology and ancient environmental studies
- Tree-ring climate responses
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Pacific and Southeast Asian Studies
- Gamma-ray bursts and supernovae
- Ionosphere and magnetosphere dynamics
- Earthquake Detection and Analysis
- Radioactivity and Radon Measurements
- Radioactive contamination and transfer
- Historical Astronomy and Related Studies
- Graphite, nuclear technology, radiation studies
- Radioactive Decay and Measurement Techniques
- Atmospheric chemistry and aerosols
- Plant Water Relations and Carbon Dynamics
- Geological and Geochemical Analysis
- Solar Radiation and Photovoltaics
- Radiation Detection and Scintillator Technologies
- X-ray Spectroscopy and Fluorescence Analysis
- Magnetic confinement fusion research
- Ancient and Medieval Archaeology Studies
- Climate variability and models
Nagoya University
2016-2025
University of Arizona
2020-2023
Institut de l'Information Scientifique et Technique
2020-2023
New York University Press
2023
The University of Tokyo
2016-2019
Institute for Cosmic Ray Research
2019
Earth and Space Research
2016-2019
Hirosaki University
2016
National Institute of Polar Research
2016
RIKEN Nishina Center
2016
ABSTRACT Radiocarbon ( 14 C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating fluctuations in atmospheric C concentration. Although curves are constructed from independently archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume international both Northern...
Abstract In 2024 May, the scientific community observed intense solar eruptions that resulted in a great geomagnetic storm and auroral extensions, highlighting need to document quantify these events. This study mainly focuses on their quantification. The source active region (AR; NOAA Active Region 13664) evolved from 113 2761 millionths of hemisphere between May 4 14. AR 13664’s magnetic free energy surpassed 10 33 erg 7, triggering 12 X-class flares 8–15. Multiple interplanetary coronal...
Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale. Moreover, it is unknown if atmospheric radiocarbon enrichment events of cosmogenic origin leave spatiotemporally consistent fingerprints. Here we measure 14C content in 484 individual tree rings formed periods 770-780 and 990-1000 CE. Distinct excursions starting boreal summer 774 spring 993 ensure precise 44 records from five continents. We also identify a meridional...
Abstract Sporadic solar energetic particle (SEP) events affect the Earth’s atmosphere and environment, in particular leading to depletion of protective ozone layer atmosphere, pose potential technological even life hazards. The greatest SEP storm known for last 11 millennia (the Holocene) occurred 774–775 AD, serving as a likely worst-case scenario being 40–50 times stronger than any directly observed one. Here we present systematic analysis impact such an extreme event can have on...
Annual rings record the intensity of cosmic rays (CRs) that had entered into Earth's atmosphere. Several rapid 14C increases in past, such as 775 CE and 994CE spikes, have been reported to originate from extreme solar proton events (SPEs). Another increase, also known ca. 660 BCE event German oak tree well 10Be 36Cl ice cores, was presumed similar event; however, increase approximately 10‰ taken a rather longer rise time 3-4 years compared event, occurrence could not be simply associated an...
14C content in tree rings and 10Be concentration records polar ice core provide information about past cosmic ray intensities. The A.D. 774–775 event has been identified by measurement several from all over the world. Although quasi-decadal Dome Fuji data Antarctic also shows a sharp peak around 775, annual variations or other cores have not revealed. We measured quasi-annual concentrations approximately 763–794 core, detected clear increase (~80% above baseline) 775. However, an accurate...
Significance Carbon-14 contents in tree rings tell us information of the past cosmic ray intensities because rays produce 14 C atmosphere. We found a signature quite large increase incoming intensity mid-Holocene (the 5480 BC event) from measurement content North American rings. The cause this event is supposed to be an extremely weak sun, or combination successive strong solar bursts and variation magnetic activity. In any case, extraordinary Holocene, indicates abnormal activity compared...
The annual
Abstract The Sun is magnetically active and often produces eruptive events on different energetic temporal scales. Until recently, the upper limit of such was unknown believed to be roughly represented by direct instrumental observations. However, two types extreme were discovered recently: solar particle multi-millennial time scale super-flares sun-like stars. Both discoveries imply that might rarely produce events, called (ESE), whose energy could orders magnitude greater than anything we...
ABSTRACT We present two new millennium-long tree-ring oxygen isotope chronologies for central and northern Japan, based on 9693 annually resolved measurements of isotopes from 39 unearthed samples consisting mainly Japanese cedar ( Cryptomeria japonica ). These were developed through cross-dating widths δ 18 O data multiple covering the periods 2349–1009 BCE (1341 yr) 1412–466 (947 respectively. In combination with our published chronology dataset currently available covers past 4354 yr...
Abstract The so-called Millennium Eruption of Baitoushan Volcano is one the largest Common Era but its date has been uncertain. Recently, Oppenheimer et al. (2017) reported eruptive year as late AD 946 using a new method called carbon-14 spike matching. However, it necessary to verify their result confirm year, since only wood sample was used in study. We verified by measuring 14 C contents tree rings from another buried during eruption. succeeded reproducing 774–775 (Miyake 2012), and...
A rapid yearly increase in the radiocarbon content has been detected for period from AD 993 to 994. However, this event is supported by 14 C measurements of only one cedar tree sample, and verification necessary confirm more reliably. For purpose, study measured Japanese Hinoki rings corresponding 988 997 using accelerator mass spectrometry system at Yamagata University (YU-AMS). The result shows a significant 994, consistent with previously data tree. This marks second case detecting an...
Abstract The Carrington event of 1859 has been the strongest solar flare in observational history. It plays a crucial role shedding light on frequency and impacts past future Solar Energetic Particle (SEP) events human societies. We address impact by measuring tree‐ring 14 C with multiple replications from high‐latitude locations around comparing them mid‐latitude measurements. A transient offset following is observed high statistical significance. Our state‐of‐the‐art production transport...
ABSTRACT Two radiocarbon ( 14 C) excursions are caused by an increase of incoming cosmic rays on a short time scale found in the Late Holocene (AD 774–775 and AD 993–994), which widely explained as due to extreme solar proton events (SPE). In addition, larger event has also been reported at 5480 BC (Miyake et al. 2017a), is attributed special mode grand minimum, well another 660 (Park 2017). Clearly, other must exist, but could have different causes. order detect more such possible events,...
Single-year spikes in radiocarbon production are caused by intense bursts of radiation from space. Supernovae emit both high-energy particle and electromagnetic radiation, but it is the latter that most likely to strike atmosphere all at once cause a surge 14C production. In 1990s, was claimed supernova 1006 CE produced exactly this effect. With years 775 994 now attributed extreme solar events, attention has returned question whether historical supernovae indeed detectable using annual...
ABSTRACT The radiocarbon ( 14 C) calibration curve so far contains annually resolved data only for a short period of time. With accelerator mass spectrometry (AMS) matching the precision decay counting, it is now possible to efficiently produce large datasets annual resolution purposes using small amounts wood. intercomparison on single-year tree-ring samples presented here first investigate specifically offsets between AMS laboratories at high precision. results show that are capable...
To investigate the radiocarbon concentration of atmospheric CO 2 over past few millennia in Japan, we measured 14 C age annual rings from 3 Japanese trees with calendar dates ranging ∼2000 yr old to present, and compared tree-ring corresponding IntCal09. In some instances, ages are not consistent IntCal09 data sets. Often, tree older than those IntCal09, but younger SHCal04 The average shifts Nagoya sets 1σ errors were determined be +26 ± 36, +24 30, +16 22, +5 21, +14 22 for intervals AD...
Abstract Cosmogenic nuclides are good indicators of past cosmic ray events and variations. To verify such phenomena, it is important to evaluate them using multiple from different archives. The event in 993–994 Common Era (CE) has already been confirmed with 14 C 10 Be data, which show rapid increases the concentrations. However, data were obtained Greenland ice cores Northern Hemisphere. investigate extent increase Southern Hemisphere, we measured quasi‐annual concentrations between 980...
Abstract Prominent excursions in the number of cosmogenic nuclides (e.g., 10 Be) around 774 CE/775 document most severe solar proton event (SPE) throughout Holocene. Its manifestation ice cores is valuable for geochronology, but also solar‐terrestrial physics and climate modeling. Using ECHAM/MESSy Atmospheric Chemistry (EMAC) model combination with Warning System Aviation Exposure to SEP (WASAVIES), we investigate transport, mixing, deposition nuclide Be produced by SPE. By comparing...
In May 2024, the scientific community observed intense solar eruptions that resulted in an extreme geomagnetic storm and auroral extension, highlighting need to document quantify these events. This study mainly focuses on their quantification. The source active region (AR 13664) evolved from 113 2761 millionths of hemisphere between 4 14 2024. AR 13664's magnetic free energy surpassed 1033 erg 7 triggering 12 X-class flares. Multiple interplanetary coronal mass ejections (ICMEs) came out...
Abstract Radiocarbon ( 14 C) is produced in the atmosphere by galactic cosmic rays, which are modulated solar magnetic activity. Its content tree rings retained and provides a record of past ray intensity We have measured, with 2 year resolution, C Japanese cedar for period A.D. 600 to 760, includes small grand minimum seventh eighth centuries. Periodicity analysis data shows that there component frequency band Schwabe cycle, 12–13 years continuing throughout minimum. This fourth case an...