[A-CG35] Global Carbon Cycle Observation and Analysis

[ACG35-P01] Improved BEAMS-diurnal Model and Its Application to Study Net Ecosystem Exchange of Japanese Terrestrial Ecosystems

*Qiao Wang¹, Ryoichi Imasu¹, Yutaka Arai¹, Yasuko Mizoguchi², Hideaki Takenaka³ (1.The University of Tokyo, 2.Forestry and Forest Products Research Institute, 3.Chiba University)

Keywords:Diurnal cycle, Seasonal variations, Net Ecosystem Exchange, Gross Primary Production, Ecosystem Respiration

Cities are the hotspots of greenhouse gases emissions, contribute to 50% - 80% of the global anthropogenic carbon dioxide (CO₂) emissions. City-scale CO₂ emissions often exhibit spatial and temporal variabilities, by virtue of the heterogeneous landscape and the circadian rhythm of human activities, respectively. On top of a more accurate monitoring and verification of total CO₂ budget, improvement of the spatial and temporal variations in CO₂ emission estimations at a finer scale is also necessary. To support the update of CO₂ emission inventory via top-down approach (atmospheric transport model inversions of atmospheric CO₂), we develop a diurnal version (Wang et al., 2021) of BEAMS (Sasai et al., 2005; 2012; and 2016), a process-based biosphere model. After the model codes going through a few iterations for improvement, we extract Ecosystem Respiration (R_e) and Gross Primary Production (GPP) data partitioned from the Net Ecosystem Exchange estimates in FLUXNET2015 dataset to calibrate certain Plant Functional Type specific parameters. For each land cover type (C3 grassland, C4 grassland, cropland, deciduous broadleaf forest, evergreen broadleaf forest and evergreen needleleaf forest), we use all available measured and good quality gap-filled data from the FLUXNET2015 dataset to ensure the representativeness of calibrated parameters, thus enables flexible application of BEAMS-diurnal model at various target regions. In this study, we apply our diurnal model to estimate hourly GPP and R_e over Japan over the past decade, then we aggregate the modeled results to daily and 8-day scale for comparisons against exiting satellite products (SMAP Level 4 Carbon Data Product, Global Land Surface Satellite 8-day GPP Product, MO/YD17A2HGF gap-filled 8-day GPP, 8-day GPP from vegetation photosynthesis model), to elaborate the performance of BEAMS-diurnal.