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Atmosphere 2012, 3(3), 377-399; doi:10.3390/atmos3030377
Article

Spatio-Temporal Variability of Western Central African Convection from Infrared Observations

Received: 17 June 2012; in revised form: 16 July 2012 / Accepted: 1 August 2012 / Published: 8 August 2012
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Abstract: The present study has used Meteosat infrared brightness temperature images to investigate the regional and interannual variability of Central African cloudiness. Spatial and temporal variability were investigated using half–hourly data from the Meteosat-7 during June–July–August (JJA) of 1998–2002. The full domain of study (1.5E–17E, 1N–15N) was divided into six regions and statistics in each region were derived. Analysis of the dependence of cloud fraction to the brightness temperature threshold is explored both over land and ocean. Three diurnal cycle regimes (continental, oceanic, and coastal) are depicted according to the amplitude and peak time. Over regions of relatively flat terrain, results indicate enhancement of deep convection in the afternoon followed by a gradual decrease in the night. The diurnal cycle of convection is characterised by afternoon and early evening (around 15:00–18:00 LST) maxima located mainly downwind of the major mountain chains, and a more rapid nighttime decay. In terms of the harmonic amplitude, the diurnal signal shows significant regional contrast with the strongest manifestation over the Adamaoua Plateau and the weakest near the South Cameroon Plateau. This remarkable spatial dependence is clear evidence of orographic and heterogeneous land-surface impacts on convective development. Oceanic region exhibits weak activity of convective cloudiness with a maximum at noon. It is suggested that daytime heating of the land surface and moist environment may play a role in determining the spatial distribution of cloud fraction. This study further demonstrates the importance of the Cameroon coastline concavity and coastal mountains in regulating regional frequencies of convection and their initialization. The strength of the diurnal cycle of convective activity depends on mountain height, mean flow, coastal geometry.
Keywords: convection; cloud coverage; diurnal cycle; meteosat convection; cloud coverage; diurnal cycle; meteosat
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Vondou, D.A. Spatio-Temporal Variability of Western Central African Convection from Infrared Observations. Atmosphere 2012, 3, 377-399.

AMA Style

Vondou DA. Spatio-Temporal Variability of Western Central African Convection from Infrared Observations. Atmosphere. 2012; 3(3):377-399.

Chicago/Turabian Style

Vondou, Derbetini A. 2012. "Spatio-Temporal Variability of Western Central African Convection from Infrared Observations." Atmosphere 3, no. 3: 377-399.


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