Fig 1.1.6.8.1: Tropospheric vertical column concentrations of O3 over Africa measured by the GOME instrument in September 1997.
Image: AT2-ELS
The large signal above the Atlantic Ocean was first observed in TOMS data in earlier years.
In effect, the NO2 produced by biomass burning, other pollution and, to some extent, by lightning, results in enormous O3 plumes off the east and west coast of Africa.