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Regulated large‐scale annual shutdown of Amazonian isoprene emissions?
Author(s) -
Barkley Michael P.,
Palmer Paul I.,
De Smedt Isabelle,
Karl Thomas,
Guenther Alex,
Van Roozendael Michel
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl036843
Subject(s) - isoprene , amazonian , environmental science , atmospheric sciences , vegetation (pathology) , amazon rainforest , dry season , rainforest , climatology , geography , chemistry , ecology , geology , pathology , copolymer , biology , polymer , medicine , cartography , organic chemistry
We perform Empirical Orthogonal Function (EOF) analysis on 12 years of global GOME and SCIAMACHY formaldehyde (HCHO) column observations to determine the most significant spatial and temporal HCHO variations. In most regions, we find that HCHO variability is predominantly driven by seasonal variations of biogenic emissions and biomass burning. However, unusually low HCHO columns are consistently observed over the Amazon rainforest during the transition from the wet‐to‐dry seasons. We use MODIS leaf area and enhanced vegetation indices, to show variations in vegetation are consistent with the observed decrease in HCHO during this period (correlations of 0.69 and 0.67, respectively). Based on this evidence, we suggest isoprene emitting vegetation experience widespread leaf flushing (new leaf growth) prior to the dry season, resulting in a large‐scale annual shutdown of Amazonian isoprene emissions.