Submitted to: Proceedings of SPIE
Publication Type: Abstract Only
Publication Acceptance Date: 4/4/2008
Publication Date: 8/10/2008
Citation: Hunt, E.R., Doraiswamy, P.C., Prueger, J.H., Hatfield, J.L. 2008. Calculation of light use efficiency from net ecosystem CO2 fluxes for remotely-sensed estimates of primary production in corn and soybean [abstract]. Society of Photo-Optical and Instrumentation Engineers (SPIE) Conference. 2008 CDROM.
Technical Abstract: Measurements of net ecosystem CO2 fluxes are being routinely made all around the world to estimate the global carbon cycle. Whereas the footprint of the flux measurements is relatively large, remote sensing is still required to scale the measurements up to larger areas. The objective of this study was to calculate light use efficiency from daily net CO2 flux and the amount of daily absorbed photosynthetically active radiation (PAR). The Soil Moisture Experiment 2005 (SMEX’05) was conducted in Walnut Creek Watershed near Ames IA, during which eddy-correlation towers were used to measure net CO2 fluxes various fields of corn and soybean. Imagery from Landsat 5 Thematic Mapper (TM), Indian ResourceSat Advanced Wide Field Sensor (AWiFS), and NASA Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) were combined to estimate of the fraction of absorbed PAR over the growing season for each field. The slope between the net CO2 flux and absorbed PAR is the estimated light use efficiency. Comparison to NASA Terra Moderate Resolution Imaging Spectroradiometer (MODIS) standard data products show that the differences in net carbon flux over the Iowa region have significant differences, which could be important for the monitoring the global carbon budget. The differences in light use efficiency between corn (C4 photosynthesis) and soybean (C3 photosynthesis) indicate that crop type is an important land-cover input for estimation of global primary production from MODIS.