CYGNSS-derived soil moisture: Status, challenges and future

Algorithm for the Joint Flight of Two Uncrewed Aerial Vehicles Constituting a Bistatic Radar System for the Soil Remote Sensing

“…They can promote water-saving agriculture (Tran et al, 2015) and provide food security, especially in arid and semi-arid regions (Gago et al, 2015;Martins et al, 2021;Fugazza et al, 2022). Traditionally, SM is studied using ground-based point measurements based on interpolated lines or grids using geophysical methods (Tavakol et al, 2021) (tensiometers, neutron moisture meters, capacitive sensors, thermal impulse sensors, underground radars) (Mallet et al, 2021;Xie et al, 2022), which, despite their relatively high accuracy, have limited spatial representativeness (several square meters maximum) (Brook et al, 2020;Babaeian et al, 2021;Rohil & Mathur, 2022;Rouf et al, 2021). Over the past 50 years, active satellite observations in electromagnetic spectra (L (0.39-1.55 GHz), C (3.9-5.75 GHz) and X (5.75-5.75 GHz) and X (5.75-0.9 GHz), rarely P-band) have been used to study SM and multispectral characteristics of vegetation cover (Bargiel et al, 2013;Su et al, 2014;Ludeno et al, 2018;Li et al, 2021;.…”

“…The use of a bistatic (or multistatic) satellite radar system (GNSS-R) (Rohil & Mathur, 2022) makes it possible to partially solve the sounding depth problem by expanding the observation limits (both in angle and operating frequencies) and introducing new parameters due to signal scattering (Kaasiku et al, 2021). Despite the prospects for reflectometry of global navigation satellite signals (Bhogapurapu et al, 2022), cloud cover, vegetation cover, topography, soil structure, climate, and other factors remain significant limitations of the applicability of all remote (satellite) soil sensing methods with relatively high measurement accuracy (Zhu et al, 2019;Babaeian et al, 2021).…”