Investigating Diurnal and Seasonal Cycles of Vegetation Optical Depth Retrieved From GNSS Signals in a Broadleaf Forest

作者：Yitong Yao, Vincent Humphrey, Alexandra G. Konings, Yujie Wang, Yi Yin, Natan Holtzman, Jeffrey D. Wood, Yinon M. Bar‐On, Christian Frankenberg · 发表于：Geophysical Research Letters · 年份：2024 · DOI：10.1029/2023gl107121 · 被引用次数：27 · 研究领域：Soil Moisture and Remote Sensing、Remote Sensing in Agriculture、Remote Sensing and LiDAR Applications

Abstract Vegetation Optical Depth (VOD) has emerged as a valuable metric to quantify water stress on vegetation's carbon uptake from a remote sensing perspective. However, existing spaceborne microwave remote sensing platforms face limitations in capturing the diurnal VOD variations and global products lack site‐level validation against plant physiology. To address these challenges, we leveraged the Global Navigation Satellite System (GNSS) L‐band microwave signal, measuring its attenuation by the canopy of a temperate broadleaf forest using a pair of GNSS receivers. This approach allowed us to collect continuous VOD observations at a sub‐hourly scale. We found a significant seasonal‐scale correlation between VOD and leaf water potential. The VOD diurnal amplitude is affected by soil moisture, plant transpiration and leaf surface water. Additionally, VOD can help independently estimate plant transpiration. Our findings pave the way for a deeper understanding of response of the vegetation to water stress at finer temporal scales.