SMOS-HR: A High Resolution L-Band Passive Radiometer for Earth Science and Applications

Rodríguez-Fernández, Nemesio; Mialon, Arnaud; Merlin, Olivier; Suere, Christophe; Cabot, François; Khazâal, Ali; Costeraste, J.; Palacin, Baptiste; Rodriguez-Suquet, R.; Tournier, T.; Decoopman, T.; Anterrieu, Éric; Colom, Miguel; Morel, Jean‐Michel; Kerr, Yann H.; Rougé, Bernard; Boutin, J.; Picard, Ghislain; Pellarin, Thierry; Escorihuela, Maria-José; Bitar, Ahmad Al; Richaume, Philippe

doi:10.1109/igarss.2019.8897815

Cited by 23 publications

(15 citation statements)

References 20 publications

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“…Ship-drift currents estimated from Automated Information Systems (AIS) data [101] will also be useful for that in the coastal zone. Nevertheless, a more direct and global access to coastal SSS dynamics would require a jump in the resolution of future SSS satellite missions [102].…”

Section: Discussionmentioning

confidence: 99%

Global Analysis of Coastal Gradients of Sea Surface Salinity

Dossa

Alory

Silva³

et al. 2021

Remote Sensing

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Sea surface salinity (SSS) is a key variable for ocean–atmosphere interactions and the water cycle. Due to its climatic importance, increasing efforts have been made for its global in situ observation, and dedicated satellite missions have been launched more recently to allow homogeneous coverage at higher resolution. Cross-shore SSS gradients can bear the signature of different coastal processes such as river plumes, upwelling or boundary currents, as we illustrate in a few regions. However, satellites performances are questionable in coastal regions. Here, we assess the skill of four gridded products derived from the Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) satellites and the GLORYS global model reanalysis at capturing cross-shore SSS gradients in coastal bands up to 300 km wide. These products are compared with thermosalinography (TSG) measurements, which provide continuous data from the open ocean to the coast along ship tracks. The comparison shows various skills from one product to the other, decreasing as the coast gets closer. The bias in reproducing coastal SSS gradients is unrelated to how the SSS biases evolve with the distance to the coast. Despite limited skill, satellite products generally agree better with collocated TSG data than a global reanalysis and show a large range of coastal SSS gradients with different signs. Moreover, satellites reveal a global dominance of coastal freshening, primarily related to river runoff over shelves. This work shows a great potential of SSS remote sensing to monitor coastal processes, which would, however, require a jump in the resolution of future SSS satellite missions to be fully exploited.

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Section: Discussionmentioning

confidence: 99%

Global Analysis of Coastal Gradients of Sea Surface Salinity

Dossa

Alory

Silva³

et al. 2021

Remote Sensing

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“…This study highlights the importance of sea ice filtering. In that respect, increasing the spatial resolution of L-band interferometric radiometer measurements to 10 km, as proposed by the SMOS-HR project (Rodrıǵuez-Fernández et al, 2019), would greatly help to better filter the ocean areas partially covered by sea ice and would allow to get closer to the ice edge and to land.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

New insights into SMOS sea surface salinity retrievals in the Arctic Ocean

Supply

Boutin

Vergely

et al. 2020

Remote Sensing of Environment

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Since 2010, the Soil Moisture and Ocean Salinity (SMOS) satellite mission monitors the earth emission at L-Band. It provides the longest time series of Sea Surface Salinity (SSS) from space over the global ocean. However, the SSS retrieval at high latitudes is a challenge because of the low sensitivity L-Band radiometric measurements to SSS in cold waters and to the contamination of SMOS measurements by the vicinity of continents, of sea ice and of Radio Frequency Interferences. In this paper, we assess the quality of weekly SSS fields derived from swath-ordered instantaneous SMOS SSS (so called Level 2) distributed by the European Space Agency. These products are filtered according to new criteria. We use the pseudo-dielectric constant retrieved from SMOS brightness temperatures to filter SSS pixels polluted by sea ice.We identify that the dielectric constant model and the sea surface temperature auxiliary parameter used as prior information in the SMOS SSS retrieval induce significant systematic errors at low temperatures. We propose a novel empirical correction to mitigate those sources of errors at high latitudes.Comparisons with in-situ measurements ranging from 1 to 11 m depths spotlight huge vertical stratification in fresh regions. This emphasizes the need to consider in-situ salinity as close as possible to the sea surface when validating L-band radiometric SSS which are representative of the first top centimeter. SSS Standard deviation of differences (STDD) between weekly SMOS SSS and in-situ near surface salinity significantly decrease after applying the SSS correction, from 1.46 pss to 1.28 pss. The correlation between new SMOS SSS and in-situ near surface salinity reaches 0.94. SMOS estimates better capture SSS variability in the Arctic Ocean in comparison to TOPAZ reanalysis (STDD between TOPAZ and in-situ SSS = 1.86 pss), particularly in river plumes with very large SSS spatial gradients.

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“…Its spatial resolution (∼60 km, ∼50% lower than the SMAP and SMOS resolutions) would limit a number of applications over land, but it would be extremely useful over the ocean [18]. Aperture synthesis radiometers such as the L/S/C-band radiometer of WCOM (Water Cycle Observation Mission) [16] or SMOS-HR (SMOS-High Resolution), currently in Phase 0 at CNES [11], with a target resolution of ∼10 km, would ensure the continuity of passive L-band observations at better resolution than provided by current satellites for soil moisture studies and other land applications. We are confident that all those exciting future missions will result in a wealth of scientific discovery and many more Remote Sensing Special Issues in the future.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, using a passive radiometer over wheat and mustard fields, Meyer et al [10] showed the importance of using a time-, polarization-, and angle-dependent optical depth (τ) parameter at the field scale for accurate soil moisture retrieval. Although the importance of those parameters is probably less important at a large scale, these effects should probably be taken into account for multi-incidence angle radiometers such as the SMOS follow-on, SMOS-HR (with an increased resolution of 10 km [11]).…”

Section: Retrieval Approachesmentioning

confidence: 99%