Development of a Solar-Induced Fluorescence─Canopy Conductance Model and Its Application to Stomatal Reactive Nitrogen Deposition

The bidirectional exchange of gases between vegetation and the atmosphere is controlled by a variety of environmental factors and feedbacks that are entangled and difficult to quantify. As a result of this complexity, parameterizations of canopy conductance (Gc) in atmospheric models introduce large uncertainties and likely biases into representations of atmosphere–biosphere gas exchange. We present a novel representation of canopy conductance derived from measurements of solar-induced fluorescence (SIF) from the TROPOspheric Monitoring Instrument (TROPOMI). We show a strong linear correlation between GPP and Gc, calculated using the Penman–Monteith theory, across a variety of ecosystem types in the AmeriFlux network. We couple this Gc–GPP correlation to previous research showing a strong linear correlation between SIF and GPP and estimate Gc at a 500 m spatial resolution across the continental United States. We also combine our model with surface estimates of NO2 and PAN from WRF-Chem to estimate stomatal deposition fluxes of these gases. Our results suggest that satellite measurements of SIF can provide important constraints on model representations of stomatal activity and canopy gas exchange on regional and global scales.