Title

Spectral Indications of Unexpected Contributors to Atmospheric CO₂ Variability?

Author Info

Gary B. Hughes, University of PennsylvaniaFollow
Robert Gigengack, University of Pennsylvania
Haralambos N. Kritikos, University of Pennsylvania

Recommended Citation

Preprint version. Published in International Journal of Climatology, Volume 19, Issue 8, June 30, 1999, pages 813-819.

NOTE: At the time of publication, the author Gary B. Hughes was not yet affiliated with Cal Poly.

The definitive version is available at https://doi.org/10.1002/(SICI)1097-0088(19990630)19:8<813::AID-JOC387>3.0.CO;2-#.

Abstract

The frequency spectrum of Northern Hemisphere atmospheric CO₂ concentration shows strong periodicities at 6.2, 1.0 and 0.5 years. The 6.2 year cyclicity has been attributed to non-linear interactions between the annual cycle and the atmospheric pole tide. The yearly signal is linked to terrestrial photosynthesis; phase analysis shows that annual CO₂ minima occur at a lag of approximately 85 days from insolation maxima. Variations in the nominal yearly period occur during times of anomalous anthropogenic CO₂ production. Periodicity at 6 months represents a deviation of the yearly signal from an annual sinusoid. If the yearly signal is largely sinusoidal, a plausible source of the 6 month periodicity could be cyclic phytoplankton productivity driven by natural insolation modes. Together, the three largest spectral peaks account for over 99% of the variation in detrended CO₂ data.

Disciplines

Statistics and Probability

Copyright

1999 Royal Meteorological Society.

Publisher statement

This is the pre-peer reviewed version of the following article:Spectral indications of unexpected contributors to atmospheric CO₂ variability?, Gary B. Hughes, Robert Giegengack, and Haralambos N. Kritikos International Journal of Climatology, 19:8, Published by Wiley-Blackwell.