Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

Changes in atmospheric carbon-14 attributed to a variable sun

Journal Article · · Science; (United States)
;

The /sup 14/C production rate in the upper atmosphere changes with time because the galactic cosmic-ray flux responsible for /sup 14/C production is modulated by the changes in solar wind magnetic properties. The resulting changes in the atmospheric /sup 14/C level are recorded in tree rings and are used to calculate past /sup 14/C production rates from a carbon reservoir model that describes terrestrial carbon exchange between the atmosphere, ocean, and biosphere. These past /sup 14/C production rate changes are compared with /sup 14/C production rates determined from 20th-century neutron flux measurements, and a theory relating /sup 14/C production and solar variability, as given by geomagnetic Aa indices and sunspot numbers, is developed. This theory takes into account long-term solar changes that were previously neglected. The 860-y /sup 14/C record indicates three episodes when sunspots apparently were absent: A.D. 1654 to 1714 (Maunder minimum), 1416 to 1534 (Spoerer minimum), and 1282 to 1342 (Wolf minimum). A less precisely defined minimum occurred near A.D. 1040. The part of this record after A.D. 1645 correlates well with the basic features of the historical record of sunspot numbers. The magnitude of the calculated /sup 14/C production rates points to a further increase in cosmic-ray flux when sunspots are absent. This flux was greatest during the Spoerer minimum. A record of approximate sunspot numbers and Aa indices for the current millennium is also presented.

Research Organization:
Univ. of Washington, Seattle
OSTI ID:
5688183
Journal Information:
Science; (United States), Journal Name: Science; (United States) Vol. 207:4426; ISSN SCIEA
Country of Publication:
United States
Language:
English

Similar Records

The variable sun
Journal Article · Wed Jan 31 23:00:00 EST 1990 · Scientific American; (USA) · OSTI ID:6609318
Maunder minimum
Journal Article · Fri Jun 18 00:00:00 EDT 1976 · Science; (United States) · OSTI ID:7350906
Evidence in the auroral record for secular solar variability
Journal Article · Fri Aug 01 00:00:00 EDT 1980 · Rev. Geophys. Space Phys.; (United States) · OSTI ID:5155240

Related Subjects

500101* -- Environment
Atmospheric-- Basic Studies-- Radiometric Techniques-- (-1989)
54 ENVIRONMENTAL SCIENCES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON 14
CARBON ISOTOPES
COSMIC RAY FLUX
EARTH ATMOSPHERE
EVEN-EVEN NUCLEI
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MAGNETIC PROPERTIES
NATURAL OCCURRENCE
NEUTRON FLUX
NUCLEI
PHYSICAL PROPERTIES
RADIATION FLUX
RADIOISOTOPES
SOLAR ACTIVITY
SOLAR WIND
SUNSPOTS
YEARS LIVING RADIOISOTOPES