• refractive index;
  • anomalous propagation;
  • rainfall;
  • Gulf of Guinea


The propagation of electromagnetic waves emitted from ground-based meteorological radar is determined using high-resolution radiosonde data. In this work, a detailed analysis of surface ducts has been undertaken to determine the anomalous propagation days on the coastal site of Douala in Cameroon (4 °N, 9.7 °E) over the Gulf of Guinea. The median duct strength shows that the strongest ducts are seen in the rainy season and that the surface duct occurs more frequently during the day than at night. The duct strength seasonal variability shows a value over Douala of about − 7.2 M-units for 1200 UTC and − 4.5 M-units for 0000 UTC in January, whereas in July the duct strengths are stronger during the day (−12.8 M-units at 1200 UTC) than at night (−9.8 M-units at 0000 UTC). The Cloudsat data products for Douala and neighbouring areas during the days of 26 January 2009 at 233525 UTC and 5 July 2009 at 233552 UTC were also analysed in association with the statistical discussion. Copyright © 2012 Royal Meteorological Society