Carvill Hurricane Index

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The Carvill Hurricane Index (CHI) is an index which describes the potential for damage from an Atlantic hurricane. The CHI is used as the basis for trading hurricane futures and options on the Chicago Mercantile Exchange (CME).

Contents 1 Index Calculation 2 Index History and Data 3 Data 4 Notes

[edit] Index Calculation

The CHI takes as input two variables: the maximum sustained wind speed of a hurricane in miles per hour and the radius to hurricane force winds of a hurricane in miles (i.e. how far from the center of the hurricane winds of 74mph or greater are experienced). If the maximum sustained wind speed is denoted by V and the radius to hurricane force winds is denoted by R then the CHI is calculated as follows:

where the subscript 0 devotes reference values. For use on the CME, the reference values of 74mph and 60 miles are used for the maximum sustained wind speed and radius of hurricane force winds respectively.

[edit] Index History and Data

The development of the CHI was based on work published by Lakshmi Kantha at the Department of Aerospace Studies at the University of Colorado in Boulder, Colorado. Kantha's paper^[1] in Eos developed a number of indices based on various characteristics of hurricanes. The ReAdvisory team at the reinsurance broker RK Carvill^[2] used the basics of the Kantha paper to develop an index which became the CHI.

The data for the CHI comes from the Public Advisories issued for named storms by the National Hurricane Center. Specifically, to determine the maximum sustained wind speed, the following verbiage is looked for:

MAXIMUM SUSTAINED WINDS ARE NEAR XX MPH

To determine the radius to hurricane force winds, the following phrase is looked for:

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO XX MILES

For example, Advisory 23A^[3] for Hurricane Katrina at 1pm Central Daylight Time on Sunday, August 28th, 2005, gave the maximum sustained wind speed of 175mph and the radius of hurricane force winds of 105 miles resulting in a CHI value of 27.9.

[edit] Data

Public Advisories from the National Hurricane Center are archived back to 1998. The table below lists the CHI values for all the landfalling hurricanes since 1998 based on the NHC Public Advisories.

Table 1: Historical storms and the CHI (1998 to 2005)

Name	Year	Landfall	NHC Advisory Number	V(mph)	R(miles)	Saffir-Simpson Category	CHI
Bonnie	1998	North Carolina	31B	115	115	3	10.7
Earl	1998	Florida	11	80	115	1	4.6
Georges	1998	Mississippi	51B	105	45	2	5.1
Bret	1999	Texas	17	140	40	4	10.4
Floyd	1999	North Carolina	34A	110	115	2	9.6
Irene	1999	Florida	9	75	30	1	1.8
Lili	2002	Louisiana	48A	100	60	2	5.2
Claudette	2003	Texas	27A	75	30	1	1.8
Isabel	2003	North Carolina	49A	100	115	2	7.7
Charley	2004	Florida	18	145	30	4	10.4
Frances	2004	Florida	44A	105	75	2	6.6
Ivan	2004	Alabama	55B	130	105	3	13.5
Jeanne	2004	Florida	49B	115	70	3	8.0
Dennis	2005	Florida	25B	120	40	3	6.9
Katrina	2005	Florida	9	75	15	1	1.4
Katrina	2005	Louisiana	26A	145	120	4	19.0
Rita	2005	Texas	26B	120	85	3	9.9
Wilma	2005	Florida	36	125	90	3	11.2

Prior to 1998, the data becomes sparse. However, using data from the HURSAT^[4] database at NOAA it is possible to construct a set of CHI values for storms back to 1983.

Modeled data is available from a number of sources:

• Seasonal data, suitable for use in the insurance and reinsurance community, is provided by Applied Insurance Research
• Atmospheric and Environmental Research, Inc. provide CHI values for live storms through their hCast-SR product
• MDA Federal provide a real-time CHI forecasting product

[edit] Notes

1. ^ L. Kantha, "Time to Replace the Saffir-Simpson Hurricane Scale?", Eos, Vol. 87, No. 1, 3 January 2006
2. ^ RK Carvill website
3. ^ Katrina Advisory 23A
4. ^ Hurricane Satellite