Satellite observations of fluorescence capture the response of Amazonian productivity to seasonality and drought

Jung-Eun Lee, Jet Propulsion Lab, jung-eun.lee@jpl.nasa.gov (Presenter)
Christian Frankenberg, Jet Propulsion Laboratory / Caltech, christian.frankenberg@jpl.nasa.gov
Christiaan van der Tol, University of Twente, tol@itc.nl
Luis Guanter, University of Oxford, guanter@atm.ox.ac.uk
C Kevin Boyce, University of Chicago, ckboyce@uchicago.edu
Joshua B. Fisher, JPL, jbfisher@jpl.nasa.gov
Erric Morrow, Harvard University, emorrow@fas.harvard.edu
Joseph A Berry, Carnegie Institution for Science, joeberry@stanford.edu
Sassan S Saatchi, JPL, sasan.s.saatch@jpl.nasa.gov

There is currently disagreement as to how seasonal water stress controls Gross Primary Production (GPP) in Amazonia because direct, large-scale measurements of photosynthesis have not been available. Using new satellite measurements of chlorophyll fluorescence from GOSAT and canopy water content from QSCAT, as well as precipitation measurements from TRMM, we find that fluorescence-based GPP varies with water availability, both peaking in the wet season over Amazonian regions with substantial seasonal rainfall variability. The findings are in contrast to MODIS Leaf Area Index (LAI). Reduction in GPP in the dry season as suggested by the fluorescence observations and a canopy fluorescence model is supported by a concomitant decrease in daily storage of canopy water content within branches and leaves, implying that plant water stress limits productivity and fluorescence from stomatal closure. For the extreme 2010 drought in Amazonia10, we estimate a 0.8 Pg reduction in basin-wide GPP during the dry season in 2010.

Presentation Type:  Poster

Session:  Coupled Processes at Land-Atmosphere-Ocean Interfaces   (Mon 4:00 PM)

Associated Project(s): 

• Saatchi, Sassan: Vegetation Structure Studies ...details

Poster Location ID: 49