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Overview of the Sample Data

This example shows how you can use SAS/IML Studio to explore data about North Atlantic tropical cyclones. (A cyclone is a large system of winds that rotate about a center of low atmospheric pressure.) The data were recorded by the U.S. National Hurricane Center at six-hour intervals during the years 1988 to 2003.

The example analyzes the following variables:

category: indicator variable that corresponds to the Saffir-Simpson wind intensity scale
latitude: latitude of observation, in degrees north latitude
min_pressure: minimum central sea-level pressure, in hPa
radius_eye: radius of eye (if an eye exists), in nautical miles
wind_kts: maximum low-level sustained wind speed, in knots

The category variable is a measure of wind intensity, corresponding to the Saffir-Simpson wind intensity scale in Table 2.1.

Table 2.1 The Saffir-Simpson Intensity Scale
Category	Description	Wind Speed (Knots)
TD	Tropical depression	22–33
TS	Tropical storm	34–63
Cat1	Category 1 hurricane	64–82
Cat2	Category 2 hurricane	83–95
Cat3	Category 3 hurricane	96–113
Cat4	Category 4 hurricane	114–134
Cat5	Category 5 hurricane	135 or greater

The analysis presented in this chapter is based on Mulekar and Kimball (2004) and Kimball and Mulekar (2004). A full description of the Hurricanes data set is included in Appendix A, Sample Data Sets.