Amazon forests did not green-up during the 2005 drought
Arindam
Samanta, Boston University, arindam@bu.edu
(Presenting)
Sangram
Ganguly, NASA AMES/BAERI, sangram.ganguly@gmail.com
Hirofumi
Hashimoto, CSUMB, hirofumi.hashimoto@gmail.com
Sadashiva
Devadiga, Sigma Space Corporation/ NASA GSFC, sadashiva.devadiga-1@nasa.gov
Eric
Vermote, University of Maryland, eric@ltdri.org
Yuri
Knyazikhin, Boston University, jknjazi@bu.edu
Ramakrishna
R
Nemani, NASA AMES, nemani911@gmail.com
Ranga
B
Myneni, Boston University, ranga.myneni@gmail.com
The sensitivity of Amazon rainforests to dry-season droughts is still poorly understood, with reports of enhanced tree mortality and forest fires on one hand, and excessive forest greening on the other. Here, we report that the previous results of large-scale greening of the Amazon, obtained from an earlier version of satellite-derived vegetation greenness data – Collection 4 (C4) Enhanced Vegetation Index (EVI), are irreproducible, with both this earlier version as well as the improved, current version (C5), owing to inclusion of atmosphere-corrupted data in those results. We find no evidence of large-scale greening of intact Amazon forests during the 2005 drought – approximately 11%-12% of these drought-stricken forests display greening, while, 28%-29% show browning or no-change, and for the rest, the data are not of sufficient quality to characterize any changes. These changes are also not unique – approximately similar changes are observed in non-drought years as well. Changes in surface solar irradiance are contrary to the speculation in the previously published report of enhanced sunlight availability during the 2005 drought. There was no co-relation between drought severity and greenness changes, which is contrary to the idea of drought-induced greening. Thus, we conclude that Amazon forests did not green-up during the 2005 drought.
Presentation Type: Poster
Poster Session: Ecosystems Science
NASA TE Funded Awards Represented:
Myneni, Ranga
Global Products of Leaf Area Index and Fraction Vegetation Absorbed PAR from the Terra/Aqua MODIS and NPP VIIRS Sensors: Algorithm Refinement and Cal/Val for ESDR Proposal