Abstract :
An analysis of CO2 (carbon dioxide) concentrations (monthly values and their 12-month running means) at various locations during 1970–2001 indicated a general increase of 10% in 2–3 decades. It was not uniform and was smaller (only 1.5% in 5 years) during 1990–1995. When the long-term (3 years or more) variation was estimated by calculating 3-year running means and was subtracted from the 12-month running means, small oscillations (range less than 0.2%) were noticed with peak spacings in the QBO, QTO (quasi-biennial and quasi-triennial oscillations, 2–3 and 3–4 year) ranges. In latitudes north of 30°N, the peaks resembled the QBO of stratospheric low latitude winds (peak spacings of 28 months). For latitudes south of 30°N, CO2 changes seemed to be associated with ENSO phenomenon, though the major El Niños of 1982–1983 and 1997–1998 seemed to have caused abnormal variations ( exceeding 0.2%) only in one or two latitude belts.
