The misuse and misinterpretation of the ACE and PDI indices for hurricane energetics

The Accumulated Cyclone Energy (ACE) index and the Power Dissipation (PDI) Index are widely used as

metrics to quantify seasonal hurricane activity both in the Atlantic basin and worldwide.

It can be shown that both of these indices are based on inaccurate assumptions that lead

to a misuse and misinterpretation of the resulting index. Towards advancing the indices of

hurricane energetics that are associated with potential damage, we develop a new methodology for calculating

an integrated kinetic

energy (IKE) climatology. A simple, observation and dynamical – based radial wind

speed model is used with the Extended Best Track dataset to calculate IKE for North

Atlantic Hurricanes from 1988 to 2008. The method is evaluated against previous

methods of tropical cyclone intensity analysis, and the results are compared to traditionally misinterpreted

indices in terms of characterizing storm energetics and relating it to storm surge. It is

shown that the traditional indices are inaccurate measurements of hurricane energetics,

and the assumptions that they are based on are not valid.