R: Get top of atmosphere solar irradiance using readily...

calcTOAIrradTable {satellite} | R Documentation

## Get top of atmosphere solar irradiance using readily tabulated values

### Description

Get mean extraterrestrial solar irradiance (ESun) using published values.

### Usage

    ## S4 method for signature 'Satellite'
    calcTOAIrradTable(x, normalize = TRUE, esd)

    ## S4 method for signature 'factor'
    calcTOAIrradTable(x, normalize = TRUE, esd)

    ## S4 method for signature 'character'
    calcTOAIrradTable(x, normalize = TRUE, esd)

### Arguments

`x` | A Satellite object or sensor id ("LT4, LT5, LE7") as character.
`normalize` | Logical; if `TRUE`, ESun is normalized to mean earth-sun distance.
`esd` | Earth-sun distance (AU, can be estimated using `calcEarthSunDist`). If x is a Satellite object and esd is not supplied and necessary for normalization, it is tried to take it from the metadata, otherwise it is estimated by the day of the year using `calcEarthSunDist`.

### Details

Currently implemented sensors are Landsat 4, 5 and 7.

If results should not be normalized to a mean earth-sun distance, the actual earth-sun distance is approximated by the day of the year using `calcEarthSunDist`.

Please note that ESun values are not required for converting Landsat 8 data to reflectance as the corresponding metadata files provide coefficients necessary to convert digital numbers to radiance and reflectance (taken from https://landsat.usgs.gov/where-can-i-find-solar-exoatmospheric-spectral-irradiances-esun-values-landsat-8-oli-data.

### Value

Satellite object with ESun information added to the metadata

Vector object containing ESun for the respective band(s)

Vector object containing ESun for the respective band(s)

### References

Tabulated values of the solar irradiance for all Landsat sensors are taken from https://landsat.usgs.gov/esun.

### See Also

`calcTOAIrradRadRef` for the computation of the solar irradiance based on maximum radiation and reflection values of the dataset or `calcTOAIrradModel` for the computation of the solar irradiance based on look-up tables for the sensor's relative spectral response and solar irradiation spectral data.

See `calcEarthSunDist` for calculating the earth-sun distance based on the day of the year which is called by this function if ESun should be corrected for actual earth-sun distance.

### Examples

    path <- system.file("extdata", package = "satellite")
    files <- list.files(path, pattern = glob2rx("LE07*.TIF"), full.names = TRUE)
    sat <- satellite(files)
    calcTOAIrradTable(sat)

    calcTOAIrradTable(x = "LE7", normalize = FALSE,
                      calcEarthSunDist("2015-01-01"))

[Package satellite version 1.0.1 Index]