Modulation of African waves from the advection of upper level moisture from the Tropical Easterly Jet

Many Atlantic hurricanes develop from African waves and moves westward over the Atlantic Ocean. The impact of upper level moisture from the Asian summer monsoon region on the African waves is addressed in this study. Sensitivity experiments were done with the PSU/NCAR MM5 model to see the impact of upper level moisture from the Tropical Easterly Jet on the African waves. The integration domain spanned the whole of Africa and run with 5 km resolution. Results show that reducing the moisture at the eastern African boundary decreases the rainfall over Africa and modulates the amplitude of the African waves. Forecasts from the FSU Global Spectral model was used to compute the kinetic energy of the African waves. Numerical experiments were separately performed when the monsoonal upper level moisture is low and then compared when it is high. The kinetic energy and the magnitude of the waves were more when the upper level moisture was greater. Our studies indicate that the growth and development of the African waves is modulated by the advection of moisture from the Asian summer monsoon. The study clearly shows the connection between the Asian summer monsoon and African waves and thus affecting the hurricanes in the Atlantic.