i.emissivity(1grass) | Grass User's Manual | i.emissivity(1grass) |
i.emissivity - Computes emissivity from NDVI, generic method for sparse land.
imagery, emissivity, land flux, energy balance
i.emissivity
i.emissivity --help
i.emissivity input=name output=name
[--overwrite] [--help] [--verbose] [--quiet]
[--ui]
i.emissivity calculates the emissivity in the longwave radiation spectrum, according to the semi-empirical equation related to NDVI by Caselles et al. (1997), valid in the NDVI range of 0.16 to 0.74 (Bastiaanssen, 1995).
Caselles et al. (1997) give reference (in Table 3 and Figure 2) to both the NDVI range used (0.15 - 0.71) and the corresponding emissivity range used (0.97 - 0.99).
The emissivity is the efficiency of longwave energy returning to the atmosphere from the skin surface. The skin surface receives heat from the thermal infrared radiation of the Sun, through atmospheric interaction. A part is returned to the atmosphere fastly, and another part is kept in the surface skin to be returned later. In more scientific terms, the grey body radiation is equal to the black body radiation times the emissivity.
i.eb.netrad
Yann Chemin, GRASS Development Team
Last changed: $Date: 2016-06-06 23:50:02 +0200 (Mon, 06 Jun 2016) $
Available at: i.emissivity source code (history)
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