| Type: | Package |
| Title: | Calculation of SSEBI and Evaporative Fraction from Raster Data |
| Version: | 1.0.1 |
| Date: | 2025-10-21 |
| Description: | Calculates a modified Simplified Surface Energy Balance Index (SSEBI) and the Evaporative Fraction (EF) using geospatial raster data such as albedo and surface-air temperature difference (TS–TA). The SSEBI is computed from albedo and TS–TA to estimate surface moisture and evaporative dynamics, providing a robust assessment of surface dryness while accounting for atmospheric variations. Based on Roerink, Su, and Menenti (2000) <doi:10.1016/S1464-1909(99)00128-8>. |
| License: | GPL-3 |
| Encoding: | UTF-8 |
| RoxygenNote: | 7.3.2 |
| Imports: | dplyr, stats, terra |
| Suggests: | testthat (≥ 3.0.0) |
| NeedsCompilation: | no |
| Packaged: | 2025-10-28 17:51:10 UTC; hamelin |
| Author: | Gaelle Hamelin [aut, cre] |
| Maintainer: | Gaelle Hamelin <gaelle.hamelin@institut-agro.fr> |
| Repository: | CRAN |
| Date/Publication: | 2025-11-03 08:20:02 UTC |
Calculate the Evaporative Fraction (EF)
Description
This function calculates the EF from two rasters: albedoand the surface-air temperature difference (TS-TA). It saves the resultingEF raster to the specified output path.
Usage
calculate_EF( albedo_path, TS_TA_path, output_path, n_intervals = 20, percentile = 0.01)Arguments
albedo_path | Character. File path to the albedo raster.Must have the sameCRS and extent as the TS-TA raster. |
TS_TA_path | Character. File path to the raster of TS-TA (surface-air temperature difference).TS and TA must have the same unit of measurement (Kelvin preferably). |
output_path | Character. File path where the EF raster will be saved. |
n_intervals | Integer. Number of intervals for splitting albedo values(default: 20). |
percentile | Numeric. Percentage used for identifying wet and dry edges(default: 0.01). |
Details
The input rasters (
albedoandTS-TA) must have the same CRS (Coordinate Reference System) and extent.If they differ, the function will attempt to reproject and resample the rasters automatically.
Value
A raster object representing the Evaporative Fraction (EF).
Examples
# Paths to example data included in the packagelibrary(terra)albedo_raster <- rast(system.file("extdata", "albedo_reduced.tif", package = "ssebiEF"))TS_TA_raster <- rast(system.file("extdata", "TS_TA_reduced.tif", package = "ssebiEF"))# Output path (temporary file for example purposes)output_path <- tempfile(fileext = ".tif")# Run the functioncalculate_EF( albedo_path = albedo_raster, TS_TA_path = TS_TA_raster, output_path = output_path, n_intervals = 20, percentile = 0.01)# Print the output pathprint(output_path)Calculate the Simplified Surface Energy Balance Index (SSEBI)
Description
This function calculates the SSEBI from two rasters: albedoand the surface-air temperature difference (TS-TA). It saves the resultingSSEBI raster to the specified output path.
Usage
calculate_SSEBI( albedo_path, TS_TA_path, output_path, n_intervals = 20, percentile = 0.01)Arguments
albedo_path | Character. File path to the albedo raster.Must have the sameCRS and extent as the TS-TA raster. |
TS_TA_path | Character. File path to the raster of TS-TA (surface-air temperature difference).TS and TA must have the same unit of measurement (Kelvin preferably). |
output_path | Character. File path where the SSEBI raster will be saved. |
n_intervals | Integer. Number of intervals for splitting albedo values(default: 20). |
percentile | Numeric. Percentage used for identifying wet and dry edges(default: 0.01). |
Details
The input rasters (
albedoandTS-TA) must have the same CRS (Coordinate Reference System) and extent.If they differ, the function will attempt to reproject and resample the rasters automatically.
Value
A raster object representing the Simplified Surface Energy Balance Index (SSEBI).
Examples
# Paths to example data included in the packagelibrary(terra)albedo_raster <- rast(system.file("extdata", "albedo_reduced.tif", package = "ssebiEF"))TS_TA_raster <- rast(system.file("extdata", "TS_TA_reduced.tif", package = "ssebiEF"))# Output path (temporary file for example purposes)output_path <- tempfile(fileext = ".tif")# Run the functioncalculate_SSEBI( albedo_path = albedo_raster, TS_TA_path = TS_TA_raster, output_path = output_path, n_intervals = 20, percentile = 0.01)# Print the output pathprint(output_path)