Single-pass soil moisture retrieval using gnss-r at l1 and l5 bands: results from airborne experiment

Joan Francesc Munoz-Martin, Raul Onrubia, Daniel Pascual, Hyuk Park, Miriam Pablos, Adriano Camps, Christoph Rüdiger, Jeffrey Walker, Alessandra Monerris

Research output: Contribution to journalArticleResearchpeer-review

20 Citations (Scopus)

Abstract

Global Navigation Satellite System—Reflectometry (GNSS-R) has already proven its potential for retrieving a number of geophysical parameters, including soil moisture. However, single-pass GNSS-R soil moisture retrieval is still a challenge. This study presents a comparison of two different data sets acquired with the Microwave Interferometer Reflectometer (MIR), an airborne-based dual-band (L1/E1 and L5/E5a), multiconstellation (GPS and Galileo) GNSS-R instrument with two 19-element antenna arrays with four electronically steered beams each. The instrument was flown twice over the OzNet soil moisture monitoring network in southern New South Wales (Australia): the first flight was performed after a long period without rain, and the second one just after a rain event. In this work, the impact of surface roughness and vegetation attenuation in the reflectivity of the GNSS-R signal is assessed at both L1 and L5 bands. The work analyzes the reflectivity at different integration times, and finally, an artificial neural network is used to retrieve soil moisture from the reflectivity values. The algorithm is trained and compared to a 20-m resolution downscaled soil moisture estimate derived from SMOS soil moisture, Sentinel-2 normalized difference vegetation index (NDVI) data, and ECMWF Land Surface Temperature.

Original languageEnglish
Article number797
Number of pages20
JournalRemote Sensing
Volume13
Issue number4
DOIs
Publication statusPublished - 22 Feb 2021

Keywords

  • Airborne
  • Dual-band
  • GNSS-R
  • Soil moisture
  • Surface roughness
  • Vegetation

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