Skip to contents

Narrow-to-broadband albedo conversion

Source: R/albedo_sat.R
albedo_broad.Rd

This function converts narrowband to broadband albedo of snow and ice surfaces using the empirical relationships developed by Knap et al. (1999) , Liang (2001) , and Feng et al. (2023) .

Usage

albedo_Knap(albedo_green, albedo_NIR, saturated = FALSE)

albedo_Liang(albedo_blue, albedo_red, albedo_NIR, albedo_SWIR1, albedo_SWIR2)

albedo_Feng(albedo_blue, albedo_green, albedo_red, albedo_NIR)

Arguments

albedo_green

SpatRaster. Green band albedo (0.53-0.59 um).

albedo_NIR

SpatRaster. Near-infrared band albedo (0.85-0.88 um).

saturated

logical. If TRUE, the green band is saturated, and an expression that is only a function of the near-infrared band is used.

albedo_blue

SpatRaster. Blue band albedo (0.43-0.45 um).

albedo_red

SpatRaster. Red band albedo (0.64-0.67 um).

albedo_SWIR1

SpatRaster. Shortwave-infrared band albedo (1.57-1.65 um).

albedo_SWIR2

SpatRaster. Shortwave-infrared band albedo (2.11-2.29 um).

Value

broadband albedo (i.e., the albedo integrated over the entire solar spectrum).

References

Feng S, Cook JM, Onuma Y, Naegeli K, Tan W, Anesio AM, Benning LG, Tranter M (2023). “Remote sensing of ice albedo using harmonized Landsat and Sentinel 2 datasets: validation.” International Journal of Remote Sensing, 1–29. doi:10.1080/01431161.2023.2291000 .

Knap WH, Reijmer CH, Oerlemans J (1999). “Narrowband to broadband conversion of Landsat TM glacier albedos.” International Journal of Remote Sensing, 20(10), 2091–2110. doi:10.1080/014311699212362 .

Liang S (2001). “Narrowband to broadband conversions of land surface albedo I: Algorithms.” Remote Sensing of Environment, 76(2), 213–238. doi:10.1016/S0034-4257(00)00205-4 .

See also

preproc(), albedo_sat()

Examples

library(terra)
#> terra 1.8.60
outline <- system.file("extdata/athabasca_outline.shp", package = "SatRbedo")
blue <- system.file("extdata/athabasca_B02_20200911.tif", package = "SatRbedo")
green <- system.file("extdata/athabasca_B03_20200911.tif", package = "SatRbedo")
red <- system.file("extdata/athabasca_B04_20200911.tif", package = "SatRbedo")
nir <- system.file("extdata/athabasca_B8A_20200911.tif", package = "SatRbedo")
swir1 <- system.file("extdata/athabasca_B11_20200911.tif", package = "SatRbedo")
swir2 <- system.file("extdata/athabasca_B12_20200911.tif", package = "SatRbedo")
blue <- preproc(blue, outline)
green <- preproc(green, outline)
red <- preproc(red, outline)
nir <- preproc(nir, outline)
swir1 <- preproc(swir1, outline)
swir2 <- preproc(swir2, outline)

# Broadband albedo using Knap et al. (1999)
albedo_Knap(green, nir)
#> class       : SpatRaster 
#> size        : 207, 216, 1  (nrow, ncol, nlyr)
#> resolution  : 30, 30  (x, y)
#> extent      : 477840, 484320, 5778300, 5784510  (xmin, xmax, ymin, ymax)
#> coord. ref. : WGS 84 / UTM zone 11N (EPSG:32611) 
#> source(s)   : memory
#> varname     : athabasca_B03_20200911 
#> name        :       Green 
#> min value   : -0.05468608 
#> max value   :  1.05072313 

# Broadband albedo using Liang (2001)
albedo_Liang(blue, red, nir, swir1, swir2)
#> class       : SpatRaster 
#> size        : 207, 216, 1  (nrow, ncol, nlyr)
#> resolution  : 30, 30  (x, y)
#> extent      : 477840, 484320, 5778300, 5784510  (xmin, xmax, ymin, ymax)
#> coord. ref. : WGS 84 / UTM zone 11N (EPSG:32611) 
#> source(s)   : memory
#> varname     : athabasca_B02_20200911 
#> name        :       Blue 
#> min value   : -0.0753151 
#> max value   :  1.0227364 

# Broadband albedo using Feng et al. (2023)
albedo_Feng(blue, green, red, nir)
#> class       : SpatRaster 
#> size        : 207, 216, 1  (nrow, ncol, nlyr)
#> resolution  : 30, 30  (x, y)
#> extent      : 477840, 484320, 5778300, 5784510  (xmin, xmax, ymin, ymax)
#> coord. ref. : WGS 84 / UTM zone 11N (EPSG:32611) 
#> source(s)   : memory
#> varname     : athabasca_B02_20200911 
#> name        :      Blue 
#> min value   : 0.1658235 
#> max value   : 0.8302532