Constraints on energy dissipation in the Earth's body tide from satellite tracking and altimetry

The phase lag by which the Earth's body tide follows the tidal potential is estimated for the principal lunar semi-diurnal tide M-2. The estimate resu lts from combining recent tidal solutions from satellite tracking data and from Topex/Poseidon satellite altimeter data. Each data type is sensitive t o the body tide lag: gravitationally for the tracking solutions, geometrica lly for the altimetry. Allowance is made for the lunar atmospheric tide. Fo r the tidal potential Love number k(2), we obtain a lag epsilon of 0.20 deg rees +/- 0.05 degrees, implying an effective body tide Q of 280 and body ti de energy dissipation of 110+/-25 GW.