Semestral Journal of Centro Argentino de Meteorólogos, which is published  since 1970 and serves on the Core of Argentine Scientific Journals since 2005. Meteorologica publishes original papers in the field of atmospheric sciences and oceanography.

Registration number of intellectual property: RL-2018-42420861-APN-DNDA#MJ

ISSN 1850-468X

Volume 46 N° 1 MORE NOTES FROM THIS ISSUE

SURFACE SOIL MOISTURE ESTIMATION WITH X BAND SAR DATA

Héctor Salgado, Stella M. Zabala, Catalina Romay, Monique Bernier, Andres Jacome y Karem Chokmani

ABSTRACT

The aim of this study is to estimate and map soil moisture (SM) from Cosmo-Skymed (X band) images acquired over an agricultural basin located in the center of the province of Buenos Aires, Argentina (Latitude: 37ºS; Longitude: 60ºW approximately). The adopted approach is empirical, with a correlation between backscattering coefficient (sigma_o) and soil moisture (SM) measures, obtained simultaneously with a satellite pass. Surface (0 to 10 cm) soil moisture was measured by means of the gravimetric method in 15 agricultural parcels (sites). The linear relation between radar signal backscattering (sigma_o) and field measured SM [SM(%) = b + a . sigma_o(dB)] shows diverse coefficients and adjustments (r2), depending on orbit direction and polarization (from r2 = 0,28 for VV Ascending to r2 = 0,69 for HH Descending). Using corresponding relation equations, images were translated from sigma_o into SM (%), obtaining the SM maps (for each polarization and orbit pass). Cross-validation between measured and calculated SM was performed, computing the Root Mean Square Error (RMSE) and Normalized Mean Square Error (NMSE). Better results were obtained from Descending images, with 6,3% < RMSE < 6,9% and 1,6 < NMSE < 2,0%). Results are compared with other experiences, and future expectations are outlined.