On Variability in Satellite Terrestrial Chlorophyll Fluorescence Measurements: Relationships with Phenology and Ecosystem-Atmosphere Carbon Exchange, Vegetation Structure, Clouds, and Sun-Satellite Geometry

Joanna Joiner1,2, Yasuko Yoshida3, Luis Guanter4, Yongguang Zhang5, Alexander P Vasilkov6, Kevin M Schaefer7, Karl F Huemmrich8, Elizabeth Middleton1, Philipp Koehler5, Martin Jung9, Compton J Tucker10, Alexei Lyapustin11, Yujie Wang12, Christian Frankenberg13, Joseph A Berry14, Randal D Koster15, Rolf H Reichle11, Jung-Eun Lee16, Stephan R Kawa11, George James Collatz17, Gregory K Walker3 and Christiaan Van der Tol18, (1)NASA Goddard Space Flight Cen., Greenbelt, MD, United States, (2)NASA GSFC, Greenbelt, United States, (3)SSAI, Greenbelt, MD, United States, (4)Free University of Berlin, Berlin, Germany, (5)Freie Univ Berlin, Berlin, Germany, (6)Science Systems and Applications, Inc., Lanham, MD, United States, (7)National Snow and Ice Data Center, Cooperative Institute for Research in the Environmental Sciences, University of Colorado at Boulder, Boulder, Colorado, U.S.A, Boulder, United States, (8)NASA Goddard Space Flight Cen., Greenbelt, United States, (9)Max Planck Institute for Biogeochemistry, Jena, Germany, (10)NASA Goddard Space Flight Center, Earth Science Division, Greenbelt, MD, United States, (11)NASA Goddard Space Flight Center, Greenbelt, United States, (12)University of Maryland Baltimore County, Baltimore, MD, United States, (13)NASA Jet Propulsion Laboratory, Pasadena, United States, (14)Carnegie Institution for Science, Department of Global Ecology, Stanford, United States, (15)NASA Goddard SFC, Global Modeling and Assimilation Office, Greenbelt, United States, (16)Brown University, Earth, Environmental and Planetary Sciences, Providence, RI, United States, (17)NASA Goddard SFC, Greenbelt, MD, United States, (18)ITC, Enschede, Netherlands
Abstract:
Over the past several years, there have been several breakthroughs in our ability to detect the very small fluorescence emitted by chlorophyll in vegetation globally from space. There are now multiple instruments in space capable of measuring this signal at varying temporal and spatial resolutions. We will review the state-of-the-art with respect to these relatively new satellite measurements and ongoing studies that examine the relationships with photosynthesis. Now that we have a data record spanning more than seven years, we can examine variations due to seasonal carbon uptake, interannual variability, land-use changes, and water and temperature stress. In addition, we examine how clouds and satellite viewing geometry impact the signal. We compare and contrast these variations with those from popular vegetation indices, such as the Normalized Difference Vegetation Index (NDVI), related to the potential photosynthesis as well as with measurements from flux tower gas exchange measurements and other model-based estimates of Global Primary Productivity (GPP). Vegetation fluorescence can be simulated in global vegetation models as well as with 1D canopy radiative transport models. We will describe how the satellite fluorescence data are being used to evaluate and potentially improve these models.
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