Assessment of Aquarius Sea Surface Salinity

Kao, Hsun-Ying; Lagerloef, Gary; Lee, Tong; Melnichenko, Oleg; Meißner, Thomas; Hacker, Peter

doi:10.3390/rs10091341

Cited by 62 publications

(63 citation statements)

References 22 publications

(31 reference statements)

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“…Before the application of satellite‐retrieved salinity data, the calibration and validation of the satellite SSS were a guarantee of data accuracy and the fidelity of the research findings. Previous studies conducted salinity data quality assessments by comparing satellite SSS with in situ measurements, but mainly for SMOS and Aquarius satellite data products (Garcia‐Eidell et al, ; Kao, Lagerloef, Lee, Melnichenko, Meissner, et al, ; Köhler et al, ; Lee, ; Maqueda et al, ; Reagan et al, ; SMOS‐BEC Team, ; Tang et al, ). Due to the late launch of the SMAP satellite, there are few related studies (Meissner et al, ; W. Tang et al, ).…”

Section: Introductionmentioning

confidence: 99%

Comparison of Satellite‐Derived Sea Surface Salinity Products from SMOS, Aquarius, and SMAP

et al. 2019

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Global sea surface salinity (SSS) has been obtained from space since 2009 by the Soil Moisture and Ocean Salinity (SMOS) mission and has been further enhanced by Aquarius in 2011 and Soil Moisture Active‐Passive (SMAP) missions in 2015. Due to the differences between SMOS, Aquarius, and SMAP in the instruments used, retrieval algorithms, and error correction strategies, the quality of their gridded products are different. In this paper, we have assessed the accuracy of three satellite products using in situ gridded data and buoy data. Compared with gridded in situ salinity measurements, the monthly Aquarius data are of the best quality, reaching the mission target accuracy (0.2 PSU) in the open ocean. SMOS and SMAP agree well with in situ data in the open ocean between 40°S and 40°N (root‐mean‐square deviation [RMSD]: SMOS 0.211 PSU, SMAP 0.233 PSU). The RMSD of SMAP is lower than that of SMOS at high latitudes, which may due to the fact that the roughness correction of SMAP is based on the Aquarius geophysical model function. Meanwhile, time series comparison of salinity measured at 1 m by moored buoys indicates that satellite SSS captures variability of SSS at weekly time scales with reasonably good accuracy (RMSD: SMOS 0.25 PSU, SMAP 0.26 PSU), when excluding suspicious buoy data. Synergetic analysis of satellite SSS and Argo data indicates that satellite SSS can be applied as real‐time quality control of buoy 1‐m salinity data.

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Section: Introductionmentioning

confidence: 99%

Comparison of Satellite‐Derived Sea Surface Salinity Products from SMOS, Aquarius, and SMAP

et al. 2019

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“…The remotely sensed OWS are primarily derived from scatterometer observations (i.e., active microwave observations), but the dual polarization microwave radiometer measurements also provide valuable wind speed estimates, especially at high wind speed (above ∼15 m/s; Reul et al, ) where scatterometer measurements tend to saturate (Quilfen et al, ). SSS estimates have only been possible since the advent of satellite L‐band measurements (1.4 GHz) from the Soil Moisture and Ocean Salinity mission (SMOS; since 2009), Aquarius, and now the Soil Moisture Active and Passive mission (SMAP; Boutin et al, ; Fore et al, ; Kao et al, ; Lagerloef et al, ; Le Vine et al, ; Meissner et al, ; Reul et al, ). When averaged over 1 week, the precision on the satellite salinity over the open ocean is typically 0.2 psu (Boutin et al, ).…”

Section: Introductionmentioning

confidence: 99%

Expected Performances of the Copernicus Imaging Microwave Radiometer (CIMR) for an All‐Weather and High Spatial Resolution Estimation of Ocean and Sea Ice Parameters

et al. 2018

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Climate change resulting in ocean warming, sea level rise, and sea ice melting has consequences for the global economy, navigation, and security. The Copernicus Imaging Microwave Radiometer (CIMR) mission is a high priority candidate mission within the European Copernicus Expansion program. CIMR is designed to observe the ocean and sea ice and more particularly the Arctic environment. Sea surface temperature (SST), ocean wind speed, sea surface salinity (SSS), and sea ice concentration (SIC) are fundamental variables for understanding, monitoring, and predicting the state of the ocean and sea ice. CIMR is a conically scanning microwave radiometer imager that includes channels at 1.4, 6.9, 10.65, 18.7, and 36.5 GHz, in a Sun-synchronous polar orbit, to provide SST, ocean wind speed, SSS, and SIC with an increased accuracy and/or spatial resolution. Here we analyze the performances of the CIMR mission in terms of theoretical retrieval precision and spatial resolution on the SST, SSS, and SIC products. A careful information content analysis is conducted. The CIMR performances are compared with the Advanced Microwave Scanning Radiometer 2 and the Soil Moisture Active Passive current missions. Maps of the retrieval precision based on realistic conditions are computed. CIMR will provide SST, SSS, and SIC with a spatial resolution of 15, 55, and 5 km and a precision of 0.2 K, 0.3 psu, and 5%, respectively. The SST and SIC will be retrieved at better than 30 km from the coast. CIMR is currently in preparatory phase, and if selected, it is for a launch in the 2025+ time frame.Plain Language Summary Climate change resulting in ocean warming, sea level rise, and sea ice melting has consequences for the global economy, navigation, and security. The Copernicus Imaging Microwave Radiometer mission is a high priority candidate satellite mission within the European Copernicus Expansion program. It is designed to observe the ocean and sea ice and more particularly the Arctic environment. Sea surface temperature, ocean wind speed, sea surface salinity, and sea ice concentration are fundamental variables for understanding, monitoring, and predicting the state of the ocean and sea ice. Here we analyze the performances of this new satellite mission in terms of precision and spatial resolution on the sea surface temperature, sea surface salinity, and sea ice concentration and compare it with current missions. The Copernicus Imaging Microwave Radiometer will provide sea surface temperature, sea surface salinity, and sea ice concentration with a spatial resolution of 15, 55, and 5 km and a precision of 0.2 K, 0.3 psu, and 5%, respectively. This satellite mission is currently in preparatory phase, and if selected, it is for a launch in the 2025 time frame.

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“…To this end, we let k 1 = 0.16 and k 2 = 2500. The value of x qual was determined using Equation (10). Then, the gridded SSS values with distance weighting were obtained for different values of k 3 .…”

Section: Interpolation Methodsmentioning

confidence: 99%

“…To assess and validate the accuracy of the Aquarius gridded SSS fields, tests have been conducted in both global oceans and regional basins [6][7][8][9]. Official Aquarius version 5.0 products have been published, and the accuracy of the monthly L3 1 • SSS fields has been estimated via a triple point analysis using individual matchups among Aquarius data, Argo float data and Hybrid Coordinate Ocean Model (HYCOM) data [10,11]. The triple point analysis results showed that the monthly average RMSD of the Aquarius L3 field data was 0.128 psu, whereas the mean RMSD between the weekly The Aquarius SSS L2 (version 5.0) products from September 2011 to May 2015 are used in this paper.…”

Section: Introductionmentioning

confidence: 99%

Aquarius Sea Surface Salinity Gridding Method Based on Dual Quality–Distance Weighting

Qian

Ren

2019

Remote Sensing

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A new method for improving the accuracy of gridded sea surface salinity (SSS) fields is proposed in this paper. The method mainly focuses on dual quality–distance weighting of the Aquarius level 2 along-track SSS data according to quality flags, which represent nonnominal data conditions for measurements. In the weighting progress, 14 data conditions were considered, and their geospatial distributions and influences on the SSS were also visualized and evaluated. Three interpolation methods were employed, and weekly gridded SSS maps were produced for the period from September 2011 to May 2015. These maps were evaluated via comparisons with concurrent Argo buoy measurements. The results show that the proposed method improved the accuracy of the SSS fields by approximately 36% compared to the officially released weekly level 3 products and yielded root mean squared difference (RMSD), correlation and bias values of 0.19 psu, 0.98 and 0.01 psu, respectively. These findings indicate a significant improvement in the accuracy of the SSS fields and provide a better understanding of the influences of different conditions on salinity.

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Assessment of Aquarius Sea Surface Salinity

Cited by 62 publications

References 22 publications

Comparison of Satellite‐Derived Sea Surface Salinity Products from SMOS, Aquarius, and SMAP

Comparison of Satellite‐Derived Sea Surface Salinity Products from SMOS, Aquarius, and SMAP

Expected Performances of the Copernicus Imaging Microwave Radiometer (CIMR) for an All‐Weather and High Spatial Resolution Estimation of Ocean and Sea Ice Parameters

Aquarius Sea Surface Salinity Gridding Method Based on Dual Quality–Distance Weighting

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