Fatras C. auteur aut IRD Borderies P. auteur aut IRD Frappart F. auteur aut IRD Mougin E. auteur aut IRD Blumstein D. auteur aut IRD Nino Fernando auteur aut IRD text journalArticle eng text/pdf reformatted digital access Radar altimetry provides information on the topography of the Earth surface. It is commonly used for the monitoring not only sea surface height but also ice sheets topography and inland water levels. The radar altimetry backscattering coefficient, which depends on surface roughness and water content, can be related to surface properties such as surface soil moisture content. In this study, the influence of surface soil moisture on the radar altimetry echo and backscattering coefficient is analyzed over semi-arid areas. A semi-empirical model of the soil's complex dielectric permittivity that takes into account that small-scale roughness and large-scale topography was developed to simulate the radar echoes. It was validated using waveforms acquired at Ku and Ka-bands by ENVISAT RA-2 and SARAL AltiKa respectively over several sites in Mali. Correlation coefficients ranging from 0.66 to 0.94 at Ku-band and from 0.27 to 0.96 at Ka-band were found. The increase in surface soil moisture from 0.02 to 0.4 (i. e., the typical range of variations in semi-arid areas) increase the backscattering from 10 to 15 dB between the core of the dry and the maximum of the rainy seasons. specialized radar altimetry waveform dielectric permittivity soil moisture MALI SAHEL AFRIQUE DE L'OUEST ZONE SEMIARIDE 126 072 10 4 art. 582 [23 p.] 2018 2072-4292 https://www.documentation.ird.fr/hor/fdi:010073602 10.3390/rs10040582 2072-4292 [F B010073602] https://www.documentation.ird.fr/hor/fdi:010073602 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers18-08/010073602.pdf IRD - Base Horizon / Pleins textes 2018-09-03 2023-07-11 fdi:010073602 fre