Weak interaction in the African Easterly Jet

Abstract. Low-frequency, African Easterlies Waves (AEW) are examined as disturbances embedded in the mid-tropospheric easterly jet of the African low troposphere. The solution to the nonlinear vorticity equation relevant to the description of waves is sought in the form of triplet waves. The latest suggest a unified method to determine their kinetics characteristic and to explain the mechanism of energy exchange between their different modes. The period of energy interaction between different modes of the global wave is equal to 3.5 days when the wave packet is moving with a group velocity dependent on the mean basic flow. The effects of nonlinearity are also identified, and it is noted that the horizontal shears of mean flow, as well as the temporal variation of the amplitude wave functions, are the controlling factors.

Keywords. Meteorology and atmospheric dynamics (Synoptic-scale meteorology; Tropical meteorology; Waves and tides)