county_wind {hurricaneexposure}

Hurricane exposure by wind for counties

Description

This function takes a list of US counties, based on their 5-digit Federal Information Processing Standard (FIPS) codes, boundaries on the range of years to be considered, and thresholds for wind speed (in meters per second) (or, alternatively, duration of winds at or above 20 m / s in minutes) for each county to be considered "exposed" to the storm. Based on these inputs, the function returns a dataframe with the subset of Atlantic basin storms meeting those criteria for each of the listed counties.

Usage

county_wind(
  counties,
  start_year,
  end_year,
  wind_limit,
  wind_var = "vmax_sust",
  wind_source = "modeled"
)

Arguments

counties

Character vector of the five-digit Federal Information Processing Standard (FIPS) codes for counties for which the user wants to determine storm exposure.

start_year

Four-digit integer with first year to consider.

end_year

Four-digit integer with last year to consider.

wind_limit

A numeric vector of length one giving the minimum wind speed (in meters per second) or duration of winds of 20 m / s or more (in minutes) to use in the filter. The units of this variable will depend on the user's choice for the wind_var parameter. If the Extended Best Tracks wind radii are used as the source of the wind data, the sustained winds will only be available for cutpoints of 34 knots, 50 knots, and 64 knots, so these values should be used (e.g., to get all counties with winds of 34 knots or higher, you could use wind_limit = 17.4, with the limit given as a value just below 34 knots in the units meters per second).

wind_var

A character string giving the wind variable to use. Choices are "vmax_sust" (maximum sustained winds; default), "vmax_gust" (maximum gust winds), "sust_dur" (minutes of sustained winds of 20 m / s or higher) and "gust_dur" (minutes of gust winds of 20 m / s or higher). If the Extended Best Tracks wind radii are used as the source of wind data, the "gust_dur" option cannot be selected.

wind_source

A character string specifying the source to use for the winds. Options are "modeled", for estimates based on running a wind model from Best Tracks data inputs, and "ext_tracks", for estimates based on the wind radii in the Extended Best Tracks data. See the help files for the datasets storm_winds and ext_tracks_wind in the hurricaneexposuredata package for more details on each of these sources for wind estimates. For the gust wind estimates, these are based on applying a gust factor of 1.49 to the sustained wind estimates in both wind data sources.

Details

For more information on how wind speeds are modeled in this data, see the documentation for the stormwindmodel R package.

Value

Returns a dataframe with a row for each county-storm pair and with columns for:

• storm_id: Unique storm identifier with the storm name and year, separated by a hyphen(e.g., "Alberto-1988", "Katrina-2005")

• fips: County's 5-digit Federal Information Processing Standard (FIPS) code

• max_sust: Maximum sustained wind speed (in m / s)

• max_gust: Maximum gust wind speed (in m / s)

• sust_dur: Minutes sustained wind speed was 20 m / s or higher

• gust_dur: Minutes gust wind speed was 20 m / s or higher (only returned if the modeled winds are requested using wind_source)

• usa_atcf_id: United States Automated Tropical Cyclone Forecasting storm identifier

• closest_time_utc: Time, in UTC, of the closest approach of the storm to the county's population mean center, based on storm tracks linearly interpolated to 15-minute increments.

• storm_dist: Minimum distance (in kilometers) between the storm's track and the county's population mean center.

• local_time: Local time of the closest approach of the storm to the county's population mean center, based on storm tracks linearly interpolated to 15-minute increments.

• closest_date: Date (based on local time) of the closest approach of the storm to the county's population mean center.

Note

Only counties in states in the eastern half of the United States can be processed by this function. Winds are modeled at 15-minute increments, so all duration estimates (sust_dur and gust_dur in the output) will be divisible by 15.

Examples

# Ensure that data package is available before running the example.
#  If it is not, see the `hurricaneexposure` package vignette for details
# on installing the required data package.
if (requireNamespace("hurricaneexposuredata", quietly = TRUE)) {

county_wind(counties = c("22071", "51700"),
            start_year = 1988, end_year = 2005,
            wind_limit = 20, wind_var = "vmax_sust")
}