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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ISPRS-Archives</journal-id>
<journal-title-group>
<journal-title>The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences</journal-title>
<abbrev-journal-title abbrev-type="publisher">ISPRS-Archives</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">2194-9034</issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/isprsarchives-XL-7-W3-337-2015</article-id>
<title-group>
<article-title>Performance of the Enhanced Vegetation Index to Detect Inner-annual Dry Season and Drought Impacts on Amazon Forest Canopies</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Brede</surname>
<given-names>B.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Verbesselt</surname>
<given-names>J.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Dutrieux</surname>
<given-names>L.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Herold</surname>
<given-names>M.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Laboratory of Geo-Information Science and Remote Sensing, Wageningen University, Droevendaalsesteeg 3, 6708PB, Wageningen, The Netherlands (benjamin.brede@wur.nl, jan.verbesselt@wur.nl, Loic.Dutrieux@wur.nl)</addr-line>
</aff>
<pub-date pub-type="epub">
<day>29</day>
<month>04</month>
<year>2015</year>
</pub-date>
<volume>XL-7/W3</volume>
<fpage>337</fpage>
<lpage>344</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2015 B. Brede et al.</copyright-statement>
<copyright-year>2015</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/3.0/">https://creativecommons.org/licenses/by/3.0/</ext-link></license-p>
</license>
</permissions>
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<self-uri xlink:href="https://isprs-archives.copernicus.org/articles/XL-7-W3/337/2015/isprs-archives-XL-7-W3-337-2015.pdf">The full text article is available as a PDF file from https://isprs-archives.copernicus.org/articles/XL-7-W3/337/2015/isprs-archives-XL-7-W3-337-2015.pdf</self-uri>
<abstract>
<p>The Amazon rainforests represent the largest connected forested area in the tropics and play an integral role in the global carbon cycle.
In the last years the discussion about their phenology and response to drought has intensified. A recent study argued that seasonality in
greenness expressed as Enhanced Vegetation Index (EVI) is an artifact of variations in sun-sensor geometry throughout the year. We
aimed to reproduce these results with the Moderate-Resolution Imaging Spectroradiometer (MODIS) MCD43 product suite, which
allows modeling the Bidirectional Reflectance Distribution Function (BRDF) and keeping sun-sensor geometry constant. The derived
BRDF-adjusted EVI was spatially aggregated over large areas of central Amazon forests. The resulting time series of EVI spanning the
2000-2013 period contained distinct seasonal patterns with peak values at the onset of the dry season, but also followed the same pattern
of sun geometry expressed as Solar Zenith Angle (SZA). Additionally, we assessed EVI’s sensitivity to precipitation anomalies. For that
we compared BRDF-adjusted EVI dry season anomalies to two drought indices (Maximum Cumulative Water Deficit, Standardized
Precipitation Index). This analysis covered the whole of Amazonia and data from the years 2000 to 2013. The results showed no
meaningful connection between EVI anomalies and drought. This is in contrast to other studies that investigate the drought impact
on EVI and forest photosynthetic capacity. The results from both sub-analyses question the predictive power of EVI for large scale
assessments of forest ecosystem functioning in Amazonia. Based on the presented results, we recommend a careful evaluation of the
EVI for applications in tropical forests, including rigorous validation supported by ground plots.</p>
</abstract>
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