Ocean Heat Content: Quotation

Metrics of hurricane-ocean interaction: vertically-integrated or vertically-averaged ocean temperature?

J. F. Price

Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA


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The first ocean metric that took account of the subsurface ocean temperature, called upper Ocean Heat Content (OHC), was written down by Leipper and Volgenau (1972) almost forty years ago OHC(x, y) = ρoCp integral 0 - Z26 (Ti(x, y, z) − 26)dz, (3) and is today widely used in operational, hurricane forecasting (Goni and Trinanes, 2003; DeMaria et al., 2005; and see especially the informative, recent review by Mainelli et al., 2008). The leading factors, ρo=1025 kg m−3 and Cp=4.0×103 J kg−1 ◦C −1 are sea water density and heat capacity and the lower limit of integration is the depth of the 26◦C isotherm, Z26. The reference temperature, 26◦C, is an average (dry bulb) temperature in the subtropical atmospheric boundary layer and so Ti(x, y, z=0)−26 is a measure of the thermal disequilibrium between the atmosphere and the initial state of the ocean. Aside from ρo and Cp, which are effectively constants, OHC has an obvious interpretation as how much (temperature × thickness) ocean temperature at a given (x, y) exceeds the reference temperature, 26◦C, and expressed as a heat content. Notice that in the usual case that ocean temperature is monotonically increasing toward the surface, water having a temperature less than 26◦C will make no contribution to OHC. A consequence is that OHC can not show how far below the reference temperature the ocean temperature may be, an issue that arises in Sect. 3.1.2.1


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Ocean Sci., 5, 351–368, 2009 www.ocean-sci.net/5/351/2009/ © Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License.