Sample Data Sets

Hurricanes Data

The U.S. National Hurricane Center records intensity and track information for tropical cyclones at six-hour intervals. The Hurricanes data set is an "extended best-track" (EBT) data set that adds six measured size parameters to the best-track data. The data were prepared by DeMaria, Pennington, and Williams (2004). The cyclones from 1988 to 2003 are included.

The version distributed with Stat Studio is Version 1.6, released February 2004. An earlier version of the EBT data was analyzed in Mulekar and Kimball (2004) and Kimball and Mulekar (2004).

The data as assembled by DeMaria include the following variables.

name

storm name

date

date of observation, in SAS date format

hms

time of observation (UTC), in SAS time format

latitude

latitude of observation, in degrees north latitude

longitude

longitude of observation. Note: DeMaria encodes this variable as degrees west longitude. For ease of plotting, this variable is recoded as a (usually) negative value in degrees east longitude.

wind_kts

maximum low-level sustained wind speed, in knots

min_pressure

minimum central sea-level pressure, in hPa

pressure_outer_isobar

pressure of outer closed isobar, in hPa

radius_eye

radius of eye (if an eye exists), in nautical miles. Note: A nautical mile is one minute of latitude, or approximately 1.15 statute miles.

radius_max_wind

radius at which maximum wind speed was measured, in nautical miles

radius_64kt

average radius of 64-knot (hurricane strength) winds, in nautical miles

radius_50kt

average radius of 50-knot winds, in nautical miles

radius_34kt

average radius of 34-knot (tropical storm strength) winds, in nautical miles

radius_outer_isobar

radius of outer closed isobar, in nautical miles

storm_type

indicator of whether the system was purely tropical, subtropical, or extra-tropical

month

month

day

day of the month

time

time of day (UTC)

year

year

ID

storm identification number

radius_34kt_ne

radius of 34-knot (tropical storm strength) winds northeast of the storm's center, in nautical miles

radius_34kt_se

radius of 34-knot (tropical storm strength) winds southeast of the storm's center, in nautical miles

radius_34kt_sw

radius of 34-knot (tropical storm strength) winds southwest of the storm's center, in nautical miles

radius_34kt_nw

radius of 34-knot (tropical storm strength) winds northwest of the storm's center, in nautical miles

radius_50kt_ne

radius of 50-knot winds northeast of the storm's center, in nautical miles

radius_50kt_se

radius of 50-knot winds southeast of the storm's center, in nautical miles

radius_50kt_sw

radius of 50-knot winds southwest of the storm's center, in nautical miles

radius_50kt_nw

radius of 50-knot winds northwest of the storm's center, in nautical miles

radius_64kt_ne

radius of 64-knot (hurricane strength) winds northeast of the storm's center, in nautical miles

radius_64kt_se

radius of 64-knot (hurricane strength) winds southeast of the storm's center, in nautical miles

radius_64kt_sw

radius of 64-knot (hurricane strength) winds southwest of the storm's center, in nautical miles

radius_64kt_nw

radius of 64-knot (hurricane strength) winds northwest of the storm's center, in nautical miles

The storm_type variable is encoded as follows:

	Tropical system
W	Tropical wave
D	Tropical disturbance
S	Subtropical storm
E	Extra-tropical storm
L	Remnant low

In addition to these variables, the data set contains the following variables, suggested in the analyses of Mulekar and Kimball (2004) and Kimball and Mulekar (2004). Missing values were converted to the SAS missing value.

category

indicator variable corresponding to the Saffir-Simpson wind intensity scale

wind_mph

maximum low-level sustained wind speed, in miles per hour. This variable is computed as wind_kts times 1.15.

radius_64kt

average of nonmissing values of the 64-knot radii in the northeast, southeast, southwest, and northwest directions

radius_50kt

average of nonmissing values of the 50-knot radii in the northeast, southeast, southwest, and northwest directions

radius_34kt

average of nonmissing values of the 34-knot radii in the northeast, southeast, southwest, and northwest directions

The category variable is encoded according to the value of wind_kts (wind speed) as in Table A.1.

Table 35.1: 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