Comparative analysis of CYGNSS-derived soil moisture and its spatiotemporal distribution across Egypt and Africa

Soil Moisture Content (SMC) is a crucial variable which affects the Earth’s environmental processes, such as water cycle, energy balance, and carbon cycle along most spatial and temporal scales. Global Navigation Satellite System Reflectometry (GNSS-R) has become a very powerful system that is used in all fields. The UCAR/CU CYGNSS that was launched by NASA use The reflected GNSS signals at the L-band and receive it in Low Earth Orbit satellites (LEO) for monitoring many factors such as SMC. Using SMC data obtained from UCAR/CU, a comparative analysis was performed against soil moisture data from SMAP, SMOS, CEDA, and ERA5, employing tolerance and interpolation techniques. Additionally, the distribution of soil moisture across Egypt and Africa were analyzed using CYGNSS during the study period from day 077 of 2017 to day 365 of 2021. The results of the comparative analysis between CYGNSS and SMAP, SMOS, CEDA, and ERA5 using the tolerance technique after removing the data more than 3σ revealed overall correlation values of 0.78, 0.64, 0.74, and 0.80, respectively, with RMSE values of 0.022, 0.018, 0.027, and 0.035 cm3/cm3 respectively. The results from data interpolation on selected days after removing the data more than 3σ showed overall correlation values of 0.76, 0.47, 0.54, and 0.39, respectively, with RMSE values of 0.03, 0.065, 0.045, and 0.076 cm3/cm3 respectively. These findings show the good performance of CYGNSS in predicting soil moisture over Egypt.