i.eb.netrad(1grass)

💖 i.eb.netrad — the net radiation bestie 💖

okay so welcome to i.eb.netrad(1grass), aka your GRASS User's Manual entry for the net radiation approximation module. it's giving SEBAL energy balance era and honestly? we're obsessed. 🦋

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✨ NAME ✨

i.eb.netrad — Net radiation approximation (Bastiaanssen, 1995). no cap, that's literally it. 👑

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🌸 KEYWORDS 🌸

imagery, energy balance, net radiation, SEBAL

like... the vibe tags for this module, iykyk. 🎀

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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]

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🚩 Flags:

• --overwrite — bestie this lets your output files overwrite existing files. use with intention, ok? 💅
• --help — prints the usage summary. your lil cheat sheet. ✨
• --verbose — verbose module output, so it tells you EVERYTHING. main character energy. 👑
• --quiet — quiet module output. shhh. 🤫
• --ui — forces launching the GUI dialog. for when you want the pretty buttons. 🎀

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🧚 Parameters:

• albedo=name [required] — Name of albedo raster map [0.0;1.0]
• ndvi=name [required] — Name of NDVI raster map [-1.0;+1.0]
• temperature=name [required] — Name of surface temperature raster map [K]
• localutctime=name [required] — Name of 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 [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, exactly the way it's done in the SEBAL model of Bastiaanssen (1995). it's faithful, it's iconic, it ate. 💅

what does it want from you? a whole lil friend group of inputs:

• 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)
• sun zenith angle

that's the whole squad. bring all of them or the module's not going anywhere. 🫶

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📝 NOTES 📝

okay history lesson, bestie. 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'd probably wanna try something in this line — because this is to calculate atmospherical energy balance. ✨

in the same way, a standard tsw is used in those equations. refer to r_net.c for that, and for other non-used equations — they're stored in there for further research convenience. so like, they're not lost, they're just chillin'. 💜

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🚧 TODO 🚧

Add more explanations.

yeah. that's the whole todo. the author said "we'll expand later" and honestly? relatable. 😭

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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)

academic baddies, both of them. 🎓✨

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👀 SEE ALSO 👀

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

go read those next, bestie, they're the extended universe. 🦋

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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)

Latest change: Friday Apr 17 01:04:26 2026 in commit: 32a143358df26b2e518b03c7e0d79541e8d1e5b1

Main index | Imagery index | Topics index | Keywords index | Graphical index | Full index

© 2003-2026 GRASS Development Team, GRASS 8.5.0 Reference Manual

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and that's the whole page, bestie!! 🎀 this was i.eb.netrad(1grass) from the GRASS 8.5.0 Reference Manual, footer date Friday Apr 17 01:04:26 2026, and that commit hash is not gonna memorize itself. slay, hydrate, and go compute some net radiation. 💅✨🦋 periodt.