[A-CG33] 静止軌道衛星による陸面観測

[ACG33-05] On the relationship between photosynthesis measures from OzFlux tower sites and Himawari-8 geostationary observations

★Invited Papers

*Alfredo R Huete¹、Qiaoyun Xie¹、Ngoc Nguyen Tran^1,2 (1.University of Technology Sydney、2.School of Information and Communication Technology, Hanoi University of Science and Technology)

キーワード：Himawari-8, geostationary satellites, OzFlux, phenology, climate variability, ecosystems

Estimations of gross ecosystem production (GEP) and photosynthetic capacity (Pc) are crucial to understanding the global carbon cycle and the impact of climate change. Eddy covariance (EC) flux towers from the OzFlux network in Australia, provide in-situ, sub-daily and seasonal measurements of photosynthetic fluxes across a wide range of ecosystem types, encompassing both meteorology-driven and phenology-driven plant productivity, as well as combinations of the two drivers. Further, Australia’s extreme climate variability present many challenges for satellite remote sensing to accurately capture vegetation dynamics, particularly given their ecohydrologically sensitivity. In this study, we used GEP and Pc estimates from eight OzFlux sites, encompassing arid grasslands and woodlands; dry and wet savannas; and dry to wet sclerophyll evergreen forests. The sub daily, daily, and seasonal flux measures were related to geostationary Himawari-8 satellite measures of vegetation at equivalent temporal scales. The advanced Himawari imager (AHI) provides unparalleled high-temporal imagery over Australian ecosystems to better understand how they function by tracking important sub-daily and daily processes over multiple years. In addition to cross-temporal scale comparisons between satellite and in-situ measures of productivity, we further wished to assess the role and extent to which plant phenological and meteorologic processes can be related with tower flux photosynthesis measures under climate variability.

Our results show great potential of Himawari-8 data in providing continuous temporal estimations of vegetation dynamics. Wet pulse events in arid regions were more clearly represented in the Himawari-8 data. Phenology-driven savanna dynamics, depicted from Himawari-8 and tower fluxes were strongly synchronised, and meteorologically driven flux tower measures of GEP in wet sclerophyll evergreen forests were completely out of phase with satellite measures of vegetation. Enhancing our biophysical understanding of vegetation dynamics will enable better predictions of how ecosystems will respond to simultaneous stressors such as climate change (warming, extreme events, flash droughts) and other disturbance regimes. These processes govern Australia’s ecosystems and heavily influence the ecosystem services they provide.