Rapid-onset flash droughts may cause devastating impacts on both ecosystems and human communities. We found that widely used multispectral satellite methods typically failed to capture the initial physiological response of forests to flash drought. Using a 3D radiative transfer model, we showed that canopy reflectance remained largely unchanged in the early stages of flash drought, even when upper-canopy leaves were wilting. We developed a new method based on a two-source energy balance model (TSEB-SM) driven by satellite infrared and soil moisture observations to capture water-flux dynamics in forests affected by flash drought. TSEB-SM tracked early-stage flash drought dynamics in China, where 8-daily transpiration declined by mean values of 14% (summer) and 6% (autumn) during the first two weeks of flash drought. Our results demonstrate that satellite-driven energy balance models can accurately track the temporal response of forests to flash drought, providing new tools for forest management in a warming climate. A new model that integrates satellite-based thermal and soil-moisture observations into a two-source energy balance framework accurately captures rapid forest responses to flash droughts, as validated by multi-source field data.
Song et al. (Tue,) studied this question.