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<h2>NAME</h2>
<em><b>i.albedo</b></em>  - Computes broad band albedo from surface reflectance.
<h2>KEYWORDS</h2>
<a href="imagery.html">imagery</a>, <a href="topic_albedo.html">albedo</a>, <a href="keywords.html#reflectance">reflectance</a>, <a href="keywords.html#satellite">satellite</a>, <a href="keywords.html#Landsat">Landsat</a>, <a href="keywords.html#ASTER">ASTER</a>, <a href="keywords.html#AVHRR">AVHRR</a>, <a href="keywords.html#MODIS">MODIS</a>
<h2>SYNOPSIS</h2>
<div id="name"><b>i.albedo</b><br></div>
<b>i.albedo --help</b><br>
<div id="synopsis"><b>i.albedo</b> [-<b>mnl8acd</b>] <b>input</b>=<em>name</em>[,<i>name</i>,...] <b>output</b>=<em>name</em>  [--<b>overwrite</b>]  [--<b>help</b>]  [--<b>verbose</b>]  [--<b>quiet</b>]  [--<b>ui</b>] 
</div>

<div id="flags">
<h3>Flags:</h3>
<dl>
<dt><b>-m</b></dt>
<dd>MODIS (7 input bands:1,2,3,4,5,6,7)</dd>

<dt><b>-n</b></dt>
<dd>NOAA AVHRR (2 input bands:1,2)</dd>

<dt><b>-l</b></dt>
<dd>Landsat 5+7 (6 input bands:1,2,3,4,5,7)</dd>

<dt><b>-8</b></dt>
<dd>Landsat 8 (7 input bands:1,2,3,4,5,6,7)</dd>

<dt><b>-a</b></dt>
<dd>ASTER (6 input bands:1,3,5,6,8,9)</dd>

<dt><b>-c</b></dt>
<dd>Aggressive mode (Landsat)</dd>
<dd>Albedo dry run to calculate some water to beach/sand/desert stretching, a kind of simple atmospheric correction</dd>

<dt><b>-d</b></dt>
<dd>Soft mode (MODIS)</dd>
<dd>Albedo dry run to calculate some water to beach/sand/desert stretching, a kind of simple atmospheric correction</dd>

<dt><b>--overwrite</b></dt>
<dd>Allow output files to overwrite existing files</dd>
<dt><b>--help</b></dt>
<dd>Print usage summary</dd>
<dt><b>--verbose</b></dt>
<dd>Verbose module output</dd>
<dt><b>--quiet</b></dt>
<dd>Quiet module output</dd>
<dt><b>--ui</b></dt>
<dd>Force launching GUI dialog</dd>
</dl>
</div>

<div id="parameters">
<h3>Parameters:</h3>
<dl>
<dt><b>input</b>=<em>name[,<i>name</i>,...]</em>&nbsp;<b>[required]</b></dt>
<dd>Name of input raster map</dd>

<dt><b>output</b>=<em>name</em>&nbsp;<b>[required]</b></dt>
<dd>Name for output raster map</dd>

</dl>
</div>
<div class="toc">
<h4 class="toc">Table of contents</h4>
<ul class="toc">
    <li class="toc"><a href="#description" class="toc">DESCRIPTION</a></li>
    <li class="toc"><a href="#notes" class="toc">NOTES</a></li>
    <li class="toc"><a href="#example" class="toc">EXAMPLE</a></li>
    <li class="toc"><a href="#todo" class="toc">TODO</a></li>
    <li class="toc"><a href="#see-also" class="toc">SEE ALSO</a></li>
    <li class="toc"><a href="#references" class="toc">References</a></li>
    <li class="toc"><a href="#author" class="toc">AUTHOR</a></li>
</ul>
</div>
<h2><a name="description">DESCRIPTION</a></h2>

<em>i.albedo</em> calculates the albedo, that is the Shortwave surface
reflectance in the range of 0.3-3 micro-meters.  It takes as input
individual bands of surface reflectance originating from MODIS, AVHRR, Landsat
or Aster satellite sensors and calculates the albedo for those.  This is
a precursor to <em>r.sun</em> and any energy-balance processing.

<h2><a name="notes">NOTES</a></h2>

It uses for Landsat 8 the weighted average reflectance (temporary solution
until an algorithm is found).
<p>
It assumes MODIS product surface reflectance in [0;10000].

<h2><a name="example">EXAMPLE</a></h2>
The following example creates the raster map "albedo_lsat7_1987" from the 
LANDSAT-TM5 bands in the North Carolina dataset:
<div class="code"><pre>
g.region raster=lsat5_1987_10 -p
i.albedo -l input=lsat5_1987_10,lsat5_1987_20,lsat5_1987_30,lsat5_1987_40,lsat5_1987_50,lsat5_1987_70 output=albedo_lsat7_1987
</pre></div>
<p>
<center>
<img src="i_albedo_landsat5.png" alt="i.albedo LANDSAT-TM5 1987 example"><br>
<i>Figure: Resulting albedo map from LANDSAT 5</i>
</center>
<p>
The following example creates the raster map "albedo_lsat7_2000" from the 
LANDSAT-TM7 bands in the North Carolina dataset:
<div class="code"><pre>
g.region raster=lsat7_2000_10 -p
i.albedo -l input=lsat7_2000_10,lsat7_2000_20,lsat7_2000_30,lsat7_2000_40,lsat7_2000_50,lsat7_2000_70 output=albedo_lsat7_2000
</pre></div>
<p>
<center>
<img src="i_albedo_landsat7.png" alt="i.albedo LANDSAT-TM7 2000 example"><br>
<i>Figure: Resulting albedo map from LANDSAT 7</i>
</center>

<h2><a name="todo">TODO</a></h2>

Maybe change input requirement of MODIS to [0.0-1.0]?

<h2><a name="see-also">SEE ALSO</a></h2>

<em>
<a href="r.sun.html">r.sun</a>,
<a href="i.vi.html">i.vi</a>
</em>

<h2><a name="references">References</a></h2>
For a 2 band determination of the Aster BB Albedo see the following:
<p>
Salleh and Chan, 2014. Land Surface Albedo Determination: Remote Sensing
and Statistical Validation. in proceedings of FIG 2014
(<a href="https://www.fig.net/resources/proceedings/fig_proceedings/fig2014/papers/ts05g/TS05G_salleh_chan_6910.pdf">PDF</a>)

<h2><a name="author">AUTHOR</a></h2>

Yann Chemin

<!--
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<i>Last changed: $Date$</i>
--><h2>SOURCE CODE</h2>
<p>Available at: <a href="https://github.com/OSGeo/grass/tree/master/imagery/i.albedo">i.albedo source code</a> (<a href="https://github.com/OSGeo/grass/commits/master/imagery/i.albedo">history</a>)</p>
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&copy; 2003-2020
<a href="http://grass.osgeo.org">GRASS Development Team</a>,
GRASS GIS 7.8.5 Reference Manual
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