HeatIndex

Zusammenfassung

Calculates apparent temperature based on ambient temperature and relative humidity. The apparent temperature is often described as how hot it feels to the human body.

Diskussion

The formula that the Heat Index function uses to compute heat index is as follows:

``````Heat Index = ( -42.379 + (2.04901523 * T) + (10.14333127 * R)
- (0.22475541 * TR) - (6.83783e-3 * TT) - (5.481717e-2 * RR)
+ (1.22874e-3 * TTR) + (8.5282e-4 * TRR) - (1.99e-6 * TTRR) )``````

where:

• T = Air temperature
• R = Relative humidity

For more information about how this function works, see the Heat Index 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.

Syntax

`HeatIndex (temperature_raster, relative_humidity_raster, {temperature_unit}, {heat_index_unit})`
 Parameter Erläuterung Datentyp temperature_raster Ein Einzelband-Raster, in dem Pixelwerte die Umgebungslufttemperatur darstellen. Raster relative_humidity_raster A single-band raster where pixel values represent relative humidity as a percentage value between 0 and 100. Raster temperature_unit Die mit dem Eingabe-Temperatur-Raster verknüpfte Maßeinheit. Die verfügbaren Eingabeeinheiten lauten Celsius, Fahrenheit und Kelvin.(Der Standardwert ist Fahrenheit) String heat_index_unit Die mit dem Ausgabe-Raster verknüpfte Maßeinheit. Die verfügbaren Ausgabeeinheiten lauten Celsius, Fahrenheit und Kelvin.(Der Standardwert ist Fahrenheit) String
Rückgabewert
 Datentyp Erläuterung Raster The output raster.

Codebeispiel

HeatIndex example 1

This example calculates the heat index based on ambient temperature and relative humidity from the input raster.

``````from arcpy.sa import *
out_heatindex_raster = HeatIndex("temperature", "relative_humidity", "Celsius", "Kelvin")
out_heatindex_raster.save("C:/arcpyExamples/outputs/heat_index_K.tif")``````
HeatIndex example 2

This example calculates the heat index based on ambient temperature and relative humidity 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_relative_humidity_raster  = "relativehumid.tif"

# Execute the HeatIndex function
out_heat_index_raster = HeatIndex(in_temperature_raster, in_relative_humidity_raster, "", "Celsius")

# Save the output
out_heat_index_raster.save("C:/arcpyExamples/outputs/heat_index_C.tif")``````