First Ideas/Initial Proposal

Revising Hurricane Intensity Indexes

The intensity of tropical systems has long been determined simply by the maximum wind speed within a storm; both accumulated cyclone energy (ACE) and the Saffir-Simpson Scale only utilize maximum wind speed as a factor in their calculation. These scales both fail to take into account the wind radii of a tropical system, which can affect the area of damage, the storm surge caused by the system, and the overall power of the cyclone. The project aims to redefine and update the ACE index, and perhaps the Saffir-Simpson Scale (a secondary goal) to make wind speed radii a factor in determining cyclone energy.

The potential impact of this project is the creation of an index that would be more accurately classify hurricanes and hurricane seasons by not just maximum wind speed, but a more general measurement of storm intensity based on the size of the storm and size of the wind radii. It would be helpful in determining the overall intensity and impact of a storm to a much greater extent than our current systems of measurement allow. In the past 10 years, there has been a great push in the development of a system that would account for the overall strength of a system. In a paper by Power and Reinhold (2007), the pair of researchers describe all of the attempts to update hurricane intensity indexes, saying “Alternative measures to assess hurricane destructive potential include accumulated cyclone energy (ACE; Bell et al. 2000), hurricane outer- and inner-core strengths (Weatherford and Gray 1988; Croxford and Barnes 2002), roof cladding fatigue damage index (Mahendran 1998), turbulence kinetic energy dissipation (Businger and Businger 2001), power (Emanuel 2005), and hurricane intensity and hazard indices (Kantha 2006).” There seems to be a growing consensus in the scientific community that something is wrong with the current system – both that it is not an accurate portrayal of overall hurricane intensity, and that a system that goes by merely one characteristic can produce misleading results. The paper later goes on to say that “Most of these measures have limitations related to the lack of information on the spatial extent of damaging winds. For example ACE and power are computed from the square or cube of [maximum velocity] without considering storm structure.” An update to ACE would include the storm structure as well as the maximum velocity in consideration to measure overall storm intensity.

To collect the data, I would use the same data set I used for the second part of my paper, utilizing the wind radii for storms combined with the maximum wind speed. Similarly, there is a project by the Hurricane Research Department called “surface wind analysis”, which produces some beautiful maps and represents the radii of the wind speeds incredibly well. More information on the project can be found at - http://www.aoml.noaa.gov/hrd/data_sub/wind.html. Another possibility would be hand-drawn (or computer drawn) images of storms, as well as a reconstruction of past storms and hurricane seasons using my newly developed system.

Sources:

Powell, M. D., & Reinhold, T. (2007). Tropical Cyclone Destructive Potential by Integrated Potential Energy . American Meteorological Society , 513-526.

Papers mentioned by Powell and Reinhold, as well as a version of an updated ACE index, referenced next.

Jia-Yuh Yu, C. C.-G. (2009). A Revised Accumulated Cyclone Energy Index. Geophysical Research Letters .