WindChill

Synthèse

Identifies dangerous winter conditions that, depending on exposure times to the elements, can result in frostbite or hypothermia.

Discussion

The formula the function uses to compute wind chill is as follows:

Wind Chill = 35.74 + (0.6215 * T) - (35.75 * WS^0.16) + (0.4275 * T * WS^0.16)

• T = Air Temperature in degrees Fahrenheit
• WS = Wind speed in miles per hour

For more information about how this function works, see the Wind Chill raster function.

The referenced raster dataset for the raster object is temporary. To make it permanent, you can call the raster object's save method.

Syntaxe

WindChill (temperature_raster, wind_speed_raster, {temperature_units}, {wind_speed_units}, {wind_chill_units})

Paramètre	Explication	Type de données
temperature_raster [temperature_raster,...]	Raster monocanal où les valeurs de pixel représentent la température de l’air ambiant.	Raster
wind_speed_raster [wind_speed_raster,...]	A single-band raster where pixel values represent wind speed.	Raster
temperature_units	Unité de mesure associée au raster de température en entrée. Les unités disponibles en entrée sont Celsius, Fahrenheit et Kelvin. (La valeur par défaut est Fahrenheit)	String
wind_speed_units	Defines the unit of measurement for the wind-speed raster: mph—Miles per hour km/h—Kilometers per hour m/s—Meters per second ft/s—Feet per second kn—Knots (La valeur par défaut est mph)	String
wind_chill_units	Unité de mesure associée au raster en sortie. Les unités disponibles en sortie sont Celsius, Fahrenheit et Kelvin. (La valeur par défaut est Fahrenheit)	String

Valeur renvoyée

Type de données	Explication
Raster	The output raster.

Exemple de code

WindChill example 1

Calculates wind chill based on the temperature and wind speed from the input raster.

from arcpy.sa import *
out_windchill_raster = WindChill("temperature.tif", "windspeed.tif", "",
                                 "km/h", "Celsius")
out_windchill_raster.save("C:/arcpyExamples/outputs/wind_chill_C.tif")

WindChill example 2

Calculates wind chill based on the temperature and wind speed from the input raster.

# Import system modules
import arcpy
from arcpy.sa import *

# Set the analysis environments
arcpy.env.workspace = "C:/arcpyExamples/data"

# Set the local variables
in_temperature_raster = "temperature.tif"
in_wind_speed_raster  = "windspeed.tif"

# Execute WindChill function
out_windchill_raster = WindChill(in_temperature_raster, in_wind_speed_raster,
                                 "", "knots", "Kelvin")
# Save the output
out_windchill_raster.save("C:/arcpyExamples/outputs/wind_chill_K.tif")