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.