The diurnal variation of the rate of dissipation of turbulent energy over Arecibo (18¿N, 67¿W) for the 1989 Arecibo Initiative on Dynamics of the Atmosphere (AIDA '89) campaigns from 1--10 April and 2--9 May 1989 have been estimated using the random velocity field deduced from imaging Doppler interferometry data. A method for extraction of the vertical component of the gravity wave spectrum has been applied to the random velocity. There is a tendency for the turbulence to maximize at dawn and dusk. Estimates of the RMS vertical gravity wave component range from 2 to 5 m s-1, and estimates of the RMS turbulent energy range from 5 to 100 mW kg-1. Estimates of the vertical eddy diffusivity have also been calculated, ranging from <50 to 300 m2 s-1. The buoyancy scale ranges from <100 m to 1 km. A cautionary note is added regarding the applicability of the Kolmogorov theory above 100 km.