Interannual variability of atmospheric CO2 in the Mediterranean: Measurements at the island at Lampedusa

P. Chamard, F. Thiery, A. Di Sarra, L. Ciattaglia, L. De Silvestri, P. Grigioni, F. Monteleone, S. Piacentino

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Abstract

The atmospheric concentration of carbon dioxide and other greenhouse gases has been measured weekly since 1992 at the island of Lampedusa, in the Mediterranean sea. Lampedusa is a small island located approximately 100 km east of Tunisia, and 250 km south of Sicily. The 10-yr CO2 data set has been analysed to quantify trends, and characterize semi-annual, annual and inter-annual variability. The data show an average trend of + 1.7 ppmv yr-1; the average annual cycle has an amplitude of about 9 ppmv. In the period of investigation the annual growth rate varies between 0.5 and 4.5 ppmv yr-1, and the amplitude of the annual cycle between 7 and 11 ppmv yr-1. By comparing the observed growth rate with recent estimates of carbon dioxide emissions, it is calculated that 58-61% of the emitted CO2 remains in the atmosphere. The CO2 growth rate appears to be related to large-scale dynamic phenomena, primarily El Nin̄o/Southern Oscillation (ENSO). An evident signature of the 1997-98 El Nin̄o is apparent in the CO2 record, and corresponds to a weakening of the exchange with the biosphere. A high correlation between the global average temperature and the 12-month average carbon dioxide growth rate is also found. Wind direction displays a significant inter-annual variability throughout the measurement period, possibly influencing the observed evolution of the CO2 concentration.
Original languageEnglish
Pages (from-to)83 - 93
Number of pages11
JournalTellus, Series B: Chemical and Physical Meteorology
Volume55
Issue number2
DOIs
Publication statusPublished - Apr 2003
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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