Reply to comment by T. Gerkema on "internal-tide energy over topography"

Here we have examined Kelly et al.'s [2010] and Gerkema's [2011] definitions of internal-tide pressure in a wedge connected to a flat abyss. We have found that Gerkema's [2011] definition of internal-tide pressure: (1) does not allow for wave drag, (2) is incompatible with the accepted baroclinicity condition over a flat bottom, and (3) does not produce physically relevant energy flux. Conversely, Kelly et al.'s [2010] definition of internal-tide pressure is free from these problems. We therefore conclude that Gerkema's [2011] objections to Kelly et al. [2010] are unfounded, and internal-tide pressure is most accurately defined by Kelly et al. [2010]. Contrary to the conclusions of Gerkema and van Haren [2007] and Gerkema [2011], horizontal pressure gradients are not necessary for computing depth profiles of energy flux. The method for calculating energy fluxes proposed by Kunze et al. [2002] (and modified by Kelly et al. [2010]) remains the most accurate means of assessing energetics from conductivity-temperature-depth/lowered acoustic Doppler current profiler (CTD/lowered ADCP) data.