Hour-to-hour vegetation water dynamics captured in radar backscatter: lessons learned from experimental studies

Paul Vermunt,Jasmeet Judge,Alejandro Monsivais-Huertero,Nick Van De Giesen,Vineet Kumar,Pang-Wei Liu,Saeed Khabbazan,Leila Guerriero,Susan Steele-Dunne

doi:10.5194/egusphere-egu22-482

Abstract

&lt;p&gt;In recent years, radar remote sensing has been increasingly used for studies on interactions between vegetation and hydrology. New opportunities arise for more advanced studies, as unprecedented spatiotemporal monitoring capability will be offered by the next generation of spaceborne radar instruments. To avail of these opportunities, we need a better understanding of the water dynamics in a canopy which is captured in a radar signal.&lt;/p&gt;&lt;p&gt;Here, we present our latest findings from two experimental campaigns. In these campaigns, we used a ground-based prototype L-band radar instrument to obtain sub-daily observations, and extensive hydrometeorological measurements to monitor the water flow and storage in the soil-plant-atmosphere continuum of a corn field. Estimating 15-minute fluctuations of vegetation water content (VWC), surface canopy water (dew, interception), and surface soil moisture allowed us to quantify backscatter sensitivity to each of these moisture stores.&lt;/p&gt;&lt;p&gt;It will be shown that the nocturnal cycle of dew, and the diurnal cycle of VWC have a considerably higher effect on L-band backscatter than previously assumed. Both particularly affected the vertically polarized signals. Furthermore, we will demonstrate that the non-uniform vertical distribution of moisture in the canopy is dynamic, both on seasonal and diurnal timescales. A modelling study quantified the impact this has on backscatter. Our findings demonstrate the opportunities for spaceborne sub-daily radar observations to monitor rapid vegetation water dynamics. Moreover, they offer insights for future validation field campaigns.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Vermunt, P. C., Khabbazan, S., Steele-Dunne, S. C., Judge, J., Monsivais-Huertero, A., Guerriero, L., &amp; Liu, P. W. (2020). Response of Subdaily L-Band Backscatter to Internal and Surface Canopy Water Dynamics.&amp;#160;&lt;em&gt;IEEE Transactions on Geoscience and Remote Sensing&lt;/em&gt;, 59, 7322-7337.&lt;/p&gt;&lt;p&gt;Vermunt, P. C., Steele-Dunne, S. C., Khabbazan, S., Judge, J., &amp; van de Giesen, N. C. (2021). Reconstructing Continuous Vegetation Water Content To Understand Sub-daily Backscatter Variations.&amp;#160;&lt;em&gt;Hydrology and Earth System Sciences Discussions&lt;/em&gt;, 1-26.&lt;/p&gt;

Full Text