Sentinel-1 SAR system and mission

Torres, Ramón; Navas-Traver, Ignacio; Bibby, David; Lokas, Svein; Snoeij, P.; Rommen, Björn; Osborne, Steve; Ceba-Vega, Francisco; Potin, Pierre; Geudtner, Dirk

doi:10.1109/radar.2017.7944460

Cited by 15 publications

(6 citation statements)

References 3 publications

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“…Sentinel 1 instrument noise floor diminishes sensitivity for low σ 0 . Instrument performance for the IW mode has a marked dependence with incidence angle (Torres et al, 2017). In effect, noise floor is about -25 dB at 35°which prevented sensitivity in the VH polarized returned power for the soft crust (Figure 4(a)).…”

Section: Resultsmentioning

confidence: 99%

Time Series of Salt Crusts Imaged by a Dual Polarization Spaceborne Synthetic Aperture Radar (Sar) at C-Band Over an Andean Altiplano Salar of Northern Chile

Barber

Delsouc

Perez

et al. 2020

ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci.

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Abstract. A dense time series of Synthetic Aperture Radar acquisitions at 6-day intervals between July 2017 to January 2019 collected with the C-band constellation Sentinel 1A and 1B is used to study salt crust evolution in an highland salar. Microwave response of halite crystal aggregates is linked to surface roughness of the salt crusts by means of a surface scattering model which includes multiple scattering at second order in media with complex permittivity such as brine-soil mixtures. The time series enabled to estimate co-polarised vertical-vertical backscattering coefficient variations as large as 8.8 dB on a 4-month period which implied a height standard deviation increase from 0.5 to 4.5 mm as modeled by the surface scattering model. Backscattering coefficient variations between 0.8 to 2 dB per month are found for three different crusts, which demonstrated different growth rates of the crystals. Crystal growth rate might be driven by the kind of water input (rainfall or snow in Andean salars), probably due to the negative effect of water droplets on impinging halite crystal surface in comparison to snow. Results showed that cross-polarised backscattering coefficient is sensitive to snow accumulation and appeared to be sensitive to subsurface conditions.

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Section: Resultsmentioning

confidence: 99%

Time Series of Salt Crusts Imaged by a Dual Polarization Spaceborne Synthetic Aperture Radar (Sar) at C-Band Over an Andean Altiplano Salar of Northern Chile

Barber

Delsouc

Perez

et al. 2020

ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci.

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“…Crust Type 1 Instrument noise floor diminishes sensitivity for weak backscatters. As for Sentinel-1, instrument performance for the IW mode has a marked dependence on the incidence angle [35], with a noise floor better than −28.8 dB at VH at the incidence angle of the observations. ALOS-2/PALSAR-2 noise floor is −36 dB at HH and −46 dB at HV, far beyond the lower backscattering coefficients found in the study area [36].…”

Section: Sampling Site Id Rms Height S [Cm] Correlation Length L [Cm]...mentioning

confidence: 89%

Spaceborne Radars for Mapping Surface and Subsurface Salt Pan Configuration: A Case Study of the Pozuelos Salt Flat in Northern Argentina

Lattus,

Barber,

Skoković

et al. 2024

Remote Sensing

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Lithium mining has become a controversial issue in the transition to green technologies due to the intervention in natural basins that impact the native flora and fauna in these environments. Large resources of this element are concentrated in Andean salt flats in South America, where extraction is much easier than in other geological configurations. The Pozuelos highland salt flat, located in northern Argentina (Salta’s Province), was chosen for this study due to the presence of different evaporitic crusts and its proven economic potential in lithium-rich brines. A comprehensive analysis of a 5.5-year-long time series of its microwave backscatter with Synthetic Aperture Radar (SAR) images yielded significant insights into the dynamics of their crusts. During a field campaign conducted near the acquisition of three SAR images (Sentinel-1, ALOS-2/PALSAR-2, and SAOCOM-1), field measurements were collected for computational modeling of the SAR response. The temporal backscattering coefficients for the crusts in the salt flat are directly linked to rainfall events, where changes in surface roughness, soil moisture, and water table depth represent the most critical variables. Field parameters were employed to model the backscattering response of the salt flat using the Small Slope Approximation (SSA) model. Salt concentration of the subsurface brine and the water table depth over the slightly to moderately roughed crusts were quantitatively derived from Bayesian inference of the ALOS-2/PALSAR-2 and SAOCOM-1 SAR backscattering coefficient data. The results demonstrated the potential for subsurface estimation with L-band dual-polarization images, constrained to crusts compatible with the feasibility range of the layered model.

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“…Sentinel 1 instrument noise floor reduced sensitivity for low σ 0 such as those measured at VH polarization. Instrument performance for the IW mode has a marked dependence with the incidence angle [31]. In effect, the noise floor is about −25 dB at 35 • and marginally improves to about −27 dB at angles between 39 • and 40 • , which implied a precise VH-polarized returned power from the rougher crusts solely.…”

Section: Discussionmentioning

confidence: 99%

Seasonality Analysis of Sentinel-1 and ALOS-2/PALSAR-2 Backscattered Power over Salar de Aguas Calientes Sur, Chile

Delsouc

Barber

Gallaud³

et al. 2020

Remote Sensing

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Seasonal changes control the development of salt crust over the Salar de Aguas Calientes Sur located in Andes Highlands, Chile. Precipitations throughout the Altiplanic winter (December to March) and austral winter (June to September) caused ponds to enlarge and surface salt crusts to dissolve driving roughness and dielectric features of the salar surface change over time. A four-year time series backscattering coefficient analysis, obtained by Sentinel 1 and ALOS-2/PALSAR-2 with 10 m of spatial resolution, demonstrated the capability of microwaves to discriminate seasonal patterns illustrated in this paper. Both sensors showed to be sensitive to changes in the surface crust due to weather conditions. Backscattered power gradually increased during the driest months as the rough salt crusts develop and decreased rapidly due to precipitations or flooding events, which lead to a smoothing appearance to radar. The high temporal frequency of acquisition in Sentinel 1 (5–13 scenes/month) allowed the discrimination among climate and annual seasonality and episodic events in the C-band backscatter coefficient. On the other hand, ALOS-2/PALSAR-2 showed subsurface changes at L-band since the salinity of the brine in the soil reduces the penetration depth of backscattered power for shorter wavelengths. Results might be useful to monitor salars with geographic and weather conditions similar to Salar de Aguas Calientes Sur.

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Sentinel-1 SAR system and mission

Cited by 15 publications

References 3 publications

Time Series of Salt Crusts Imaged by a Dual Polarization Spaceborne Synthetic Aperture Radar (Sar) at C-Band Over an Andean Altiplano Salar of Northern Chile

Time Series of Salt Crusts Imaged by a Dual Polarization Spaceborne Synthetic Aperture Radar (Sar) at C-Band Over an Andean Altiplano Salar of Northern Chile

Spaceborne Radars for Mapping Surface and Subsurface Salt Pan Configuration: A Case Study of the Pozuelos Salt Flat in Northern Argentina

Seasonality Analysis of Sentinel-1 and ALOS-2/PALSAR-2 Backscattered Power over Salar de Aguas Calientes Sur, Chile

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