A New Approach for Measuring Photosynthetic Light-Use Efficiency From Space Using Multi-Angular Modis Observations
Forrest
G
Hall, NASA GSFC/JCET, forrest.g.hall@nasa.gov
(Presenting)
Thomas
Hilker, Faculty of Forest Resources Management, University of British Columbia, thomas hilker Nicholas
C.
Coops, Faculty of Forest Resources Management, University of British Columbia, nicholas coops Alexei
Lyapustin, NASA Goddard Space Flight Center, Code 614.4, Greenbelt Maryland, 20771, USA, 'lyapustin, alexei i. (gsfc-614.4)[unive
T
Andrew
Black, Faculty of Land and Food Systems, University of British Columbia, andy black Yujie
Wang, NASA Goddard Space Flight Center, Code 614.4, Greenbelt Maryland, 20771, USA, 'wang, yujie (gsfc-614.4)[university of
Satellite remote sensing of Gross Primary Production (GPP) will greatly enhance our understanding of the terrestrial carbon cycle, as it allows globally continuous estimates of plant CO2 uptake at regular intervals from space. Recent decades have seen considerable progress determining PAR and fPAR from satellite observations; remote sensing of vegetation light use efficiency ε, however, remains challenging. This poster introduces a new approach for a spaceborne measurement of ε using the MODIS satellite and validation using AMSPEC, a tower-based automated, multi-angular spectroradiometer instrument. We demonstrated that AMSPEC could infer ε from a photochemical reflectance index (PRI) on a continuous, year round basis. Instead of comparing MODIS observations to tower-based measurements of ε directly, ungridded, MODIS Level 1B swath data are related to tower-based AMSPEC observations of the same wavelength and viewing geometry, acquired at the time of each satellite overpass. This approach allowed a more spatially explicit comparison between stand level and spaceborne observations and importantly, it facilitated the direct use of the MODIS observations as a multi-angular dataset. A new Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm was used to correct for atmospheric effects independent of MODIS viewing geometry. We conclude (1) that MAIAC-corrected MODIS observations were able to track the site-level physiological changes from space throughout the observation period. (2) A network of AMSPEC like spectro-radiometer instruments based on existing flux towers could greatly advance existing upscaling efforts by helping to calibrate coarser scale observations to tower-based measurements and allowing an adjustment for different vegetation and land-cover types.
Presentation Type: Poster
Poster Session: Carbon Cycle Science
NASA TE Funded Awards Represented:
Lyapustin, Alexei
Development of well-calibrated multi-sensor surface reflectance data record