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Spectral indications of unexpected contributors to atmospheric CO 2 variability?
Author(s) -
Hughes Gary B.,
Giegengack Robert,
Kritikos Haralambos N.
Publication year - 1999
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/(sici)1097-0088(19990630)19:8<813::aid-joc387>3.0.co;2-#
Subject(s) - climatology , environmental science , atmospheric sciences , meteorology , geology , geography
The frequency spectrum of Northern Hemisphere atmospheric CO 2 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 CO 2 minima occur at a lag of approximately 85 days from insolation maxima. Variations in the nominal yearly period occur during times of anomalous anthropogenic CO 2 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 CO 2 data. Copyright © 1999 Royal Meteorological Society