By measuring the vertical component of velocity in the height range 74--90 km above Troms¿ (69 ¿N, 19 ¿E), with a 1 km height resolution, we are able to estimate characteristic wavenumbers, m*. In turn, using well-established theory, these m* may be interpreted in terms of wave energy and an upper limit of the energy dissipation rate, &egr;. The time-variation of &egr; derived in this way is in general agreement with other radar, model and in situ results. These estimates, although now available with good seasonal coverage, are nevertheless for a limited height range only. In order to overcome this restriction to some degree, the results are combined with a season and height dependent model of the eddy diffusion coefficient, K to generate a picture of the seasonal variability of energy dissipation in the height regime 60--90 km. ¿ 1998 American Geophysical Union