@Article{MaedaGalv:2015:SuGeEf,
author = "Maeda, Eduardo Eiji and Galv{\~a}o, L{\^e}nio Soares",
affiliation = "{University of Helsink} and {Instituto Nacional de Pesquisas
Espaciais (INPE)}",
title = "Sun-sensor geometry effects on vegetation index anomalies in the
Amazon rainforest",
journal = "GIScience and Remote Sensing",
year = "2015",
volume = "52",
number = "3",
pages = "332--343",
keywords = "bidirectional effects, MODIS, view-illumination effects,
viewing-illumination geometry, Vegetation Indices, Amazon.",
abstract = "The capacity of orbital sensors to monitor vegetation functioning
and phenology in the Amazon rainforest using vegetation indices
(VIs) has been broadly challenged in recent years. In particular,
recent studies indicate that artifacts associated with sun-sensor
geometry are likely to have major influence on the variability of
some VIs. Nevertheless, the magnitude of this influence and the
impacts on different VIs are still poorly understood. This study
evaluates the scaling and magnitude of the phase angle variation
effects on six different VIs, as well as in the individual
spectral bands used for computing these indices. Our results show
a significant and consistent relationship between phase angle and
VI anomalies. The scaling (i.e. the change rate of VI anomaly with
phase angle) of this relationship varies according to spectral
bands and VIs. Median anomalies in individual Moderate Resolution
Imaging Spectroradiometer (MODIS) bands showed a variation of up
to \−0.045 degree\−1 , while median VI anomaly
variations reached \−0.047 degree\−1 . The scaling
of all relationships was shown to be constant throughout the year.
Average phase angle values in the Amazon basin ranged from
approximately 25 degrees in October to 41 degrees in June. Such
variation can, on average, cause changes of up to 0.75 in some
VIs, therefore having major impacts on the interpretation of the
relationships between VIs and forest phenology.",
doi = "10.1080/15481603.2015.1038428",
url = "http://dx.doi.org/10.1080/15481603.2015.1038428",
issn = "1548-1603",
label = "lattes: 5507769922001047 2 MaedaGalv:2015:SuGeEf",
language = "en",
urlaccessdate = "27 abr. 2024"
}