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 SAS/IML 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:

\ast 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

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