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    Humans are an integral component of the Earth system as conceptualised by IGBP. João Morais recalls key milestones in IGBP’s engagement with the social sciences and offers some words of advice for Future Earth.
  • IGBP and Earth observation:
    a co-evolution

    The iconic images of Earth beamed back by the earliest spacecraft helped to galvanise interest in our planet’s environment. The subsequent evolution and development of satellites for Earth observation has been intricately linked with that of IGBP and other global-change research programmes, write Jack Kaye and Cat Downy .

Meridional ozone gradients in the African upper troposphere

Geophysical Research Letters (2007)
Sauvage B, Thouret V, Cammas J-P, Brioude J, Nedelec P and Mari C
Doi: 10.1029/2006GL028542
Vol 34; Issue 3

This study presents regular observations from the MOZAIC data base over Africa (1994–2004) to highlight the role of Hadley cells in tropical ozone production. We show the presence in the African upper troposphere (9–12 km) of a minimum of ozone and of a maximum of relative humidity that both follow the meridional migration of the Inter-Tropical Convergence Zone (ITCZ). We suggest that mechanisms contributing to meridional ozone gradients (0.3 to 1.5 ppbv deg−1) on both sides of the ozone minimum in the 20°S–20°N latitude band are (1) the vertical transport of relatively poor ozone air masses by tropical convection, and (2) the photochemical production of ozone in upper-level branches of the Hadley circulation. Depending on the season and on the meridional side of the ITCZ, ozone precursors injected in the ascending branch of the ITCZ include biomass burning, biogenic, lightning and anthropogenic emissions.

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