Process-based Modeling of Solar-induced Chlorophyll Fluorescence with VISIT-SIF version 1.0

Abstract. Satellite retrievals of solar-induced chlorophyll fluorescence (SIF) can provide opportunities to improve our understanding of terrestrial ecosystem dynamics and the carbon cycle at the global scale. Here, we present a new biogeochemical process-based carbon and nitrogen cycle model for representing SIF retrievals (VISIT-SIF version 1.0) acquired by the Greenhouse gases Observing SATellite (GOSAT) with an hourly time step and a spatial resolution of approximately 0.31 × 0.31 degrees. VISIT-SIF is characterized by its ease of implementation for the representation of radiation transfer processes between surface canopy and satellite measurements. With an initial seven years of data (2009–2015), our model simulations showed a consistent global mean value of 0.51±0.39, with GOSAT SIF retrievals of 0.46±0.42 mW m^-2 sr^-1 nm^-1; the root-mean-square error was 0.29 mW m^-2 sr^-1 nm^-1. We also found that the mean seasonal variability in the simulated SIFs mostly consisted of the GOSAT SIF retrievals at the subcontinental scale. However, the simulated results indicated less sensitivity to water stress in the late dry season in arid and semiarid regions relative to that of the GOSAT SIF retrievals, which is consistent with the findings of previous studies using multiple biogeochemical process-based models. This comparison suggested that there is a critical need to improve our knowledge of SIF variability and biophysical processes in such regions.