title: Simulations of chlorophyll fluorescence incorporated into the Community Land Model version 4.
abstract: Several studies have shown that satellite retrievals of solar-induced chlorophyll fluorescence (SIF) provide useful information on terrestrial photosynthesis or gross primary production (GPP). Here, we have incorporated equations coupling SIF to photosynthesis in a land surface model, the National Center for Atmospheric Research Community Land Model version 4 (NCAR CLM4), and have demonstrated its use as a diagnostic tool for evaluating the calculation of photosynthesis, a key process in a land surface model that strongly influences the carbon, water, and energy cycles. By comparing forward simulations of SIF, essentially as a byproduct of photosynthesis, in CLM4 with observations of actual SIF, it is possible to check whether the model is accurately representing photosynthesis and the processes coupled to it. We provide some background on how SIF is coupled to photosynthesis, describe how SIF was incorporated into CLM4, and demonstrate that our simulated relationship between SIF and GPP values are reasonable when compared with satellite (Greenhouse gases Observing SATellite; GOSAT) and in situ flux-tower measurements. CLM4 overestimates SIF in tropical forests, and we show that this error can be corrected by adjusting the maximum carboxylation rate (Vmax ) specified for tropical forests in CLM4. Our study confirms that SIF has the potential to improve photosynthesis simulation and thereby can play a critical role in improving land surface and carbon cycle models.
authors.affiliation: Department of Earth, Environmental and Planetary Sciences, Brown University, P.O. Box 1846 324, Brook Street, Providence, RI, 02912, USA.
authors.forename: Jung-Eun
authors.initials: JE
authors.lastname: Lee
authors.affiliation: Geo-Information Science and Earth Observation, The University of Twente, Enschede, The Netherlands.|Department of Global Ecology, Carnegie Institution of Washington, 260 Panama St., Stanford, CA, 94305, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Berry
authors.affiliation: Geo-Information Science and Earth Observation, The University of Twente, P.O. Box 6-7500 AA, 7500 AE, Enschede, The Netherlands.
authors.forename: Christiaan
authors.initials: C
authors.lastname: van der Tol
authors.affiliation: Department of Earth, Environmental and Planetary Sciences, Brown University, P.O. Box 1846 324, Brook Street, Providence, RI, 02912, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Yang
authors.affiliation: Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Telegrafenberg Building A 17, Room 20.22, 14473, Potsdam, Germany.
authors.forename: Luis
authors.initials: L
authors.lastname: Guanter
authors.affiliation: Remote Sensing Laboratories, Department of Geography, University of Zurich, Irchel Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
authors.forename: Alexander
authors.initials: A
authors.lastname: Damm
authors.affiliation: Department of Atmospheric Science, Colorado State University, 200 West Lake Street, 1371 Campus Delivery, Fort Collins, CO, 80523-1371, USA.
authors.forename: Ian
authors.initials: I
authors.lastname: Baker
authors.affiliation: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Frankenberg
mesh_terms: D057486:Carbon Cycle; D002734:Chlorophyll / Q000378:metabolism*; D017753:Ecosystem; D005453:Fluorescence; D008954:Models, Biological; D013472:Sunlight
chemical_list: D002734:Chlorophyll
keywords: GOSAT; NCAR CLM; chlorophyll fluorescence; gross primary production; land surface model; model evaluation; remote sensing; tropical forests