Combining observations in the reflective solar and thermal domains for improved mapping of carbon, water and energy fluxes

This study investigates the utility of integrating remotely sensed estimates of leaf chlorophyll (C
_ab
) into a thermal-based Two-Source Energy Balance (TSEB) model that estimates land-surface CO
₂
and energy fluxes using an analytical, light-use-efficiency (LUE) based model of canopy resistance. Day to day variations in nominal LUE (LUE
_n
) were assessed for a corn crop field in Maryland U.S.A. through model calibration with CO
₂
flux tower observations. The optimized daily LUE
_n
values were then compared to estimates of C
_ab
integrated from gridded maps of chlorophyll content weighted over the tower flux source area. Changes in C
_ab
exhibited a curvilinear relationship with corresponding changes in daily calibrated LUE
_n
values derived from the tower flux data, and hourly water, energy and carbon flux estimation accuracies from TSEB were significantly improved when using C
_ab
for delineating spatio-temporal variations in LUE
_n
. The results demonstrate the synergy between thermal infrared and shortwave reflective wavebands in producing valuable remote sensing data for monitoring of carbon and water fluxes.