Comments on "Isentropic Analysis of a Simulated Hurricane"

TL;DR

This paper critiques previous methods of plotting moist-air isentropes in hurricanes, proposing a thermodynamically accurate definition based on the third law to improve clarity and precision.

Contribution

It introduces a new definition of moist-air entropy using the third law, enabling unambiguous isentropic analysis of hurricanes.

Findings

The third law-based entropy definition improves isentrope accuracy.

Application to hurricane DUMILE demonstrates clearer isentropic surfaces.

Most existing equivalent potential temperatures are inadequate for precise isentropic analysis.

Abstract

This paper describes Comments to the paper of Mrowiec et al. published in the J. Atmos. Sci. in May 2016 (Vol 73, Issue 5, pages 1857-1870) and entitled "Isentropic analysis of a simulated hurricane". It is explained that the plotting of isentropic surfaces (namely the isentropes) requires a precise definition of the specific moist-air entropy, and that most of existing "equivalent potential temperatures" lead to inaccurate definitions of isentropes. It is shown that the use of the third law of thermodynamics leads to a definition of the specific moist-air entropy (and of a corresponding potential temperature) which allow the plotting of unambigous moist-air isentropes. Numerical applications are shown by using a numerical simulation of the hurricane DUMILE.