[A-CG37] Biogeochemical Cycles in Land Ecosystem

[ACG37-P03] Detection of environmental stress using the Himawari-8 LST data across different climatic conditions in Australia

*Reo Shibayama¹, Yuhei Yamamoto¹, Hojin Lee², Kazuhito Ichii¹ (1.CEReS, Chiba University, 2.Seoul National University)

Keywords:Remote Sensing, heat wave, vegetation stress

In recent years, frequent occurrences of extreme climate such as heatwave and drought have been reported. Extreme hot and dry conditions cause environmental stresses for plant’s growth by reducing photosynthesis and transpiration. Detecting and understanding such environmental stresses over a wide area is important for understanding carbon and water yield of terrestrial ecosystems, and for assessing the risk of crop and forest damages. However, there is currently no means of detecting environmental stress on a diurnal scale over a wide area. A geostationary satellite is a useful tool for high-frequency observation of the surface environment over a wide area. Japan's geostationary satellite Himawari-8/9 can retrieve land surface temperature (LST) every 10 minutes, and the LST could be an indicator of the dryness of the surface as well as high temperature. Therefore, LST is expected to be applied to the detection of environmental stress. In this study, site-level experiments were conducted as a first step to apply Himawari-8 LST data to detect environmental stress at diurnal scale. Five flux observation sites across different climatic zones were selected. We examined the possibility of detecting a decrease in photosynthesis based on the daily variation of LST, air-temperature, soil moisture, and vapor pressure deficit. The decreases in photosynthesis in the daytime were expressed by gross primary production (GPP) and canopy conductance. The results showed that the decrease in GPP and canopy conductance were correlated with the daily maximum LST. The correlations were different across sites. Especially at the semi-arid sites, a sudden decrease in canopy conductance was observed at LSTs around 50 °C. The results implied that different detection methods should be considered for different climatic conditions and vegetation types.