Fuhrhop, Rolf (1988) Einfluß von Wellenstörungen auf die konvektive Bewölkung im Bereich der innertropischen Konvergenzzone über Afrika. (Diploma thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 105 pp.

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Abstract

This study is concerned with the influence of wave disturbances on deep convective cloudiness over the African continent and the adjacent Atlantic Ocean in the region of the ITCZ. It is supposed, that the growth of cloud clusters is stimulated by wave disturbances. The diurnal march of cloudiness can be intensified or suppressed by convergence and divergence of these disturbances. For this study IR- satellite pictures (METEOSAT 1) from May 2 until July 3, 1979 are used to construct Hovmoeller-diagrams and to derive time records of cloud cover for 2.5° *2.5° areas. The Hovmoeller-diagrams show a systematic westward motion of cloud clusters more frequently in June than May. Some of these cloud systems are connected with the 6 easterly waves derived by EBERZ (1987). In most cases the position of the wave trough is found west of the clusters. From the Hovmoeller-diagrams in can be concluded, that the other moving cloud systems are also connected with wave disturbances. A spectral analyse of the time records is performed, the statistical significance of the results is weak. Different periods of cloudiness for the ocean and continent are found. For periods greater than 8 days the spectral variance over the ocean is much larger than over the continent. Over the west african coast the coherence analysis shows an east-west orientated wave track for periods in the domain of 3 days and a northeast-southwest orientated wave track for periods in the domain of 10 days.

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