Closing a heat budget: effect of internal waves

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Date of Original Version



Based on the accuracy and noise levels of today's moored instrument technology, it appears that we can estimate the vertical heat flux and its divergence in (or into) the ocean if we measure the horizontal heat fluxes. However, we do not know the effect of oceanographic noise (e.g. internal waves) on the calculation of horizontal heat fluxes and their divergence. In this study, the magnitude of the error in a horizontal flux calculation for a control volume due to the presence of internal waves is investigated. We used a simple internal wave model (W. Munk, in Evolution of physical oceanography, MIT Press, pp. 264-291, 1981) to generate time series of velocity and temperature data representative of those from moorings and a simple method to determine the mean horizontal heat flux divergence. The size of the control volume and averaging time for the heat flux calculation were varied. Our results imply that a vertical heat flux difference greater than 25 W m-2 between the top and bottom of a control volume 40 km × 40 km × 40 m could be determined for averaging periods greater than 48h. We found that the magnitude of the error in the horizontal heat flux divergence, presented in terms of a vertical heat flux per unit area, increased linearly with the vertical extent of the control volume and decreased linearly with the horizontal size of the control volume. The magnitude of the error decreased with the averaging time, δQH ∞ (tavg)- 1 2. © 1994.

Publication Title, e.g., Journal

Deep-Sea Research Part I