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Meteorol Atmos Phys (2012) 118:2129 DOI 10.1007/s00703-012-0208-6
ORIGINAL PAPER
On hurricane energy
Louis M. Michaud
Received: 23 June 2011 / Accepted: 13 August 2012 / Published online: 5 September 2012 Springer-Verlag 2012
Abstract Warm seawater is the energy source for hurricanes. Interfacial sea-to-air heat transfer without spray ranges from 100 W m-2 in light wind to 1,000 W m-2 in hurricane force wind. Spray can increase sea-to-air heat transfer by two orders of magnitude and result in heat transfers of up to 100,000 W m-2. Drops of spray falling back in the sea can be 24 C colder than the drops leaving the sea, thus transferring a large quantity of heat from sea to air. The heat of evaporation is taken from the sensible heat of the remainder of the drop; evaporating approximately 0.3 % of a drop is sufcient to reduce its temperature to the wet bulb temperature of the air. The heat required to evaporate hurricane precipitation is roughly equal to the heat removed from the sea indicating that sea cooling is due to heat removal from above and not to the mixing of cold water from below. The paper shows how case studies of ideal thermodynamic processes can help explain hurricane intensity.
1 Introduction
Several methods of establishing hurricane maximum potential intensity (MPI) have been proposed; the two leading methods are E-MPI (Emanuel 1986) and H-MPI (Holland 1997). Persing and Montgomery (2003) and Bell and Montgomery (2008) noted that E-MPI has gained
much acceptance, but that E-MPI cannot account for the observed super-intensities. E-MPI is based on the heat transfer from sea to air multiplied by a Carnot efciency calculated using the temperatures of the sea for the hot source temperature and the temperature at the top of the hurricane for the cold source temperature. H-MPI is based on the pressure at the bottom of a column of air approaching equilibrium with the underlying water at the reduced eyewall pressure. Camp and Montgomery (2001) reviewed the Holland and Emanuel MPI methods; they noted that H-MPI tends to overestimate the intensity of strong hurricanes, while E-MPI tends to underestimate the same. Persing and Montgomery (2003) suggested that a new MPI formulation from rst principles is required; this paper shows that thermodynamic case...