HR: 11:35h
AN: B21H-06 INVITED     [PDF]
TI: Novel Technique for Remote Estimation of CO2 Flux in Maize and Soybean Canopies
AU: * Gitelson, A A
EM: gitelson@calmit.unl.edu
AF: University of Nebraska-Lincoln, 113 Nebraska Hall, Lincoln, NE 68588-0517 United States
AU: Verma, S B
EM: sverma1@unl.edu
AF: University of Nebraska-Lincoln, 113 Nebraska Hall, Lincoln, NE 68588-0517 United States
AU: Vina, A
EM: avina@calmit.unl.edu
AF: University of Nebraska-Lincoln, 113 Nebraska Hall, Lincoln, NE 68588-0517 United States
AU: Rundquist, D C
EM: drundquist1@unl.edu
AF: University of Nebraska-Lincoln, 113 Nebraska Hall, Lincoln, NE 68588-0517 United States
AU: Arkebauer, T J
EM: tarkebau@unlnotes.unl.edu
AF: University of Nebraska-Lincoln, 113 Nebraska Hall, Lincoln, NE 68588-0517 United States
AB: There is considerable interest in assessing the magnitude of carbon sources and sinks for agricultural lands, grasslands, and forests. Scaling-up from chamber-based measurements of plant/soil gas-exchange has shortcomings, thus other approaches, preferably those that can be implemented remotely, are needed. In this paper, we propose a novel technique to remotely assess CO2 fluxes in row crops (i.e. maize and soybean) using reflectances (r) in two spectral channels either in the red edge near 700 nm or in the green around 550 nm and the NIR (beyond 750 nm). These spectral bands are already available on several operational satellite sensors (i.e. SeaWiFS, MODIS, and MERIS). Differences of reciprocal reflectances [(rRedEdge)-1-( rNIR)-1] and [(rGreen)-1-(rNIR)-1] accounted for more than 80 percent of the variability in mid-day canopy photosynthesis of maize and soybean canopies, in a wide range of CO2 fluxes (from near zero to 2.4 mg/m2/s). The technique was validated by an independent data set; root mean square error in predicting mid-day canopy photosynthesis by [(rRedEdge)-1-(rNIR)-1] was 0.17 mg/m2/s and 0.2 mg/m2/s by [(rGreen)-1-(rNIR)-1] and the slope of the linear relationship between predicted and measured fluxes was 0.926. However, before these previously undocumented relationships between indices [(rRedEdge)-1-(rNIR)-1] and [(rGreen)-1-(rNIR)-1] and canopy photosynthesis can be employed for remote assessment of CO2 fluxes, more work is needed to answer the questions about the accuracy of estimating diurnal CO2 variation as well as the application of the technique in contrasting vegetation types (i.e. grasslands, forests).
DE: 1600 GLOBAL CHANGE (New category)
DE: 1615 Biogeochemical processes (4805)
DE: 1640 Remote sensing
DE: 1694 Instruments and techniques
SC: Biogeosciences [B]
MN: 2003 Fall Meeting