Equinox tidal heating of the upper atmosphere

Evaluations are presented of the time-average heating at different latitudes and heights due to energy flux divergence of the equinox diurnal and semidiurnal tides calculated by Forbes (1982a,h)from 0 to 400 km.It is found that diurnal tidal heating maximizes in the region of 80 km and semidiurnal has a sharp maximum at 108 km. Thermospheric diurnal oscillations give rise to a second region of heating that maximizes at 200 km and effectively transports energy from low to high latitudes.Global means are evaluated for the time-averaged vertical energy fluxes and heating rates: below 130 km, the results for the diurnal tide agree with those for the (1,1) mode alone, and for the semidiurnal tide, heating rates below 130 km are the same as those that would he obtained without the thermospheric semidiurnal excitation.Comparisons are made from 90 to 170 km between the combined diurnal and semidiurnal heating rates and previously reported rates due to e.u.v. radiation, S_q currents and gravity waves.