i.eb.netrad(1)

✨ i.eb.netrad — the net radiation approximation page ✨

okay bestie, welcome to i.eb.netrad from the GRASS GIS User's Manual 💖 this is the net radiation approximation, straight from Bastiaanssen, 1995. no cap.

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🌈 KEYWORDS 🌈

imagery, energy balance, net radiation, SEBAL

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🎀 SYNOPSIS 🎀

i.eb.netrad
i.eb.netrad --help
i.eb.netrad albedo=name ndvi=name temperature=name localutctime=name
temperaturedifference2m=name emissivity=name
transmissivity_singleway=name dayofyear=name sunzenithangle=name
output=name  [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]

🦋 Flags 🦋

• --overwrite — bestie this one lets output files overwrite existing files. iconic, but use with intention 💅
• --help — prints the usage summary, i.e. the little cheat sheet
• --verbose — verbose module output, she's chatty
• --quiet — quiet module output, she's giving silence 🤫
• --ui — forces launching the GUI dialog

🌸 Parameters 🌸

• albedo=name [required] — name of the albedo raster map, range [0.0;1.0]
• ndvi=name [required] — name of the NDVI raster map, range [-1.0;+1.0]
• temperature=name [required] — name of the surface temperature raster map, in [K]
• localutctime=name [required] — name of the time of satellite overpass raster map [local time in UTC]
• temperaturedifference2m=name [required] — name of the difference map of temperature from surface skin to about 2 m height, in [K]
• emissivity=name [required] — name of the emissivity map [-]
• transmissivity_singleway=name [required] — name of the single-way atmospheric transmissivitymap [-]
• dayofyear=name [required] — name of the Day Of Year (DOY) map [-]
• sunzenithangle=name [required] — name of the sun zenith angle map [degrees]
• output=name [required] — name of the output net radiation layer 🫶

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💜 DESCRIPTION 💜

so i.eb.netrad calculates the net radiation at the time of satellite overpass — the way it is in the SEBAL model of Bastiaanssen (1995). that's the whole vibe.

it takes input of Albedo, NDVI, Surface Skin temperature, time of satellite overpass, surface emissivity, difference of temperature from surface skin and about 2 m height (dT), instantaneous satellite overpass single-way atmospheric transmissivity (tsw), Day of Year (DOY), and sun zenith angle. literally all of it. 😌

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🔥 NOTES 🔥

ngl, in the old methods, dT was taken as flat images (dT=5.0). so if you don't have a dT map from ground data, you would want to try something in this line — this is to calculate atmospherical energy balance. same energy with tsw: a standard tsw is used in those equations.

Refer to r_net.c for that and for other non-used equations, but stored in there for further research convenience. the lore is archived, periodt 📚

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😭 TODO 😭

Add more explanations. (yes that's the whole thing, she's a work in progress, we love her anyway)

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⭐ REFERENCES ⭐

• Bastiaanssen, W.G.M., 1995. Regionalization of surface flux densities and moisture indicators in composite terrain; a remote sensing approach under clear skies in mediterranean climates. PhD thesis, Wageningen Agricultural Univ., The Netherland, 271 pp. (PDF)
• Chemin, Y., 2012. A Distributed Benchmarking Framework for Actual ET Models, in: Irmak, A. (Ed.), Evapotranspiration - Remote Sensing and Modeling. InTech. (PDF)

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👑 SEE ALSO 👑

i.eb.soilheatflux, i.eb.hsebal01, i.albedo

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💖 AUTHOR 💖

Yann Chemin, International Rice Research Institute, The Philippines

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🌟 SOURCE CODE 🌟

Available at: i.eb.netrad source code (history)

Accessed: Saturday Jan 17 05:41:39 2026

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and that's the whole page, bestie 🧚 this was GRASS GIS 8.4.2 Reference Manual energy, © 2003-2025 GRASS Development Team, and the footer vibes are GRASS 8.4.2 — i.eb.netrad(1). go calculate some net radiation, you absolute icon 💅✨