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 results from combining recent tidal solutions from satellite tracking data and from Topex/Poseidon satellite altimeter data. Each data type is sensitive to the body tide lag: gravitationally for the tracking solutions, geometrically for the altimetry. Allowance is made for the lunar atmospheric tide. For the tidal potential Love number k(2), we obtain a lag epsilon of 0.20 degrees +/- 0.05 degrees, implying an effective body tide Q of 280 and body tide energy dissipation of 110+/-25 GW.