Understanding how much water is stored in vegetation is critical for monitoring plant health, drought conditions, and the risk of wildfires. Satellites like SMAP and SMOS provide global maps of a measurement called Vegetation Optical Depth (VOD), which gives us an idea of the water content and structure of plants. However, these satellite readings are hard to verify because VOD can’t be directly measured on the ground.

To solve this problem, we are developing a new approach that combines several ground-based tools to better understand and validate VOD. In a forest in Georgia, we’ve set up stationary sensors that continuously measure how much GPS signal is blocked by vegetation over long period of time. We also use a moving robot with similar sensors to collect data along paths through the forest. Additionally, we use drones and backpack-based scanners to create detailed 3D maps of the forest structure.

Together, these tools allow us to track changes in vegetation over both time and space and compare them with satellite data. Our goal is to create a reliable and affordable method to check satellite VOD measurements, helping scientists better monitor forests and improve environmental predictions.