Microwave remote sensing missions such as ESA's SMOS are used to compute variables such as soil moisture and sea surface salinity, using the dielectric constant. This is done on large spatial resolutions of +25km.

However, high resolution SAR data is now available from (e.g.) Sentinel 1. While Sentinel 1 data is widely used for determining soil moisture properties, I cannot find any applications in which it was used to determine salinity properties of (coastal-) waters. Little to no literature can be found about this.

Am I missing any obvious reasons (maybe radar-related limitations) why this is not already done?

1 Answer 1


Fundamentally the difference between Sentinel-1 and SMOS are two closely tied elements.

  • Sentinel-1 is a C-band radar, making it an active sensor
  • SMOS is a L-band radiometer, making it a passive sensor

As such, the satellites vary in fundamental components and as such, the Sentinel-1 cannot measure salinity.
The confusing element is that both Sentinel-1 and SMOS can provide a measure for soil moisture (to some extent), but the approaches for each sensor is entirely different. Sentinel-1 based soil moisture estimates rely on the backscattering, while SMOS based measurements are based on brightness temperature.

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