Implementation and Validation of SIF in a Land Surface Model

Advances in remote sensing technology now allow for the measurement of solar-induced fluorescence (SIF), a measured change in Fraunhofer lines at energy levels equal to the light emitted from plant chlorophyll during photosynthesis. Since energy is quantized, it should be possible to closely approximate the amount of photosynthesis for a given area. Recent studies have supported this idea, with SIF data being linked to gross primary production (GPP) and successfully being used to constrain modeled GPP. This approach has the potential to dramatically improve land surface model calculations for atmospheric CO2 sequestered by vegetation. In this study, we implement SIF calculations into the Integrated Science Assessment Model (ISAM), a land surface model. SIF is first calculated at the leaf level, and then scaled spatially to the canopy level. Regression analysis is performed to compare modeled SIF with measurements retrieved from the Orbiting Carbon Observatory-2 (OCO2). We will validate the modeled SIF at two deciduous forest sites: Harvard Forest in Massachusetts and Morgan Monroe State Forest in Indiana