[A-CG44] 静止軌道衛星による陸面観測

[ACG44-P02] Determining Vegetation Critical Temperature Thresholds in Australia Using Himawari-8/9 LST data

*柴山 怜雄¹、山本 雄平¹、Hojin Lee²、市井 和仁¹ (1.千葉大学環境リモートセンシング研究センター、2.University of Freiburg)

キーワード：リモートセンシング、熱波、植生ストレス

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. Six flux observation sites across different climatic zones were selected. Canopy conductance was calculated as an indicator to determine if the vegetation was stressed. Analysis of the instantaneous LST values shows that there is a critical temperature at which high canopy conductance can no longer be maintained. Critical Temperature varied from site to site and vegetation to vegetation. Environmental stress could be detected by time series changes using Critical Temperature.