2013 SMOS-Aquarius Science Workshop

April 15-17, 2013
Brest, France

In April 2013, over 120 members of the international science community met at IFREMER (Brest, France) to discuss understanding salinity using satellites (e.g., European Space Agency's "Soil Moisture Ocean Salinity," SMOS and NASA's Aquarius instrument), in-water instruments (e.g., Argo Program), and computer models. The goal of this workshop was to provide the SMOS and Aquarius science communities with an overview on the present quality of the provided data, and an outlook on future algorithm developments.

Agenda | Abstracts | Meeting Summary
Documents (43)
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Analysing the Signature of the 2010-2011 La Niña Using In Situ, SMOS and Model Salinity Data
Hasson, A., Delcroix, T., Boutin, J., Hernandez, O., Martin, N., Alory, G., and Dussin, R. (17-Apr-13). The tropical Pacific Ocean has been in a La Niña phase from mid 2010 to early 2012. In this presentation, we will describe and analyze the well-marked signature of this ENSO phase, using a combination of in situ, SMOS- and model-derived sea surface salinity products.

Aquarius Brings New Understanding to Tropical Instability Waves (TIWs)
Lee, T., Lagerloef, G.S.E., Gierach, M.M. Kao, H-Y., Yueh, S., and Dohan, K. (17-Apr-13). Sea surface salinity (SSS) measurements from Aquarius/SAC-D satellite provide the first satellite observations of the salinity structure of tropical instability waves in the Pacific and Atlantic Oceans. In the tropical Pacific, the associated SSS anomaly has a magnitude of approximately ±0.5 PSU.

Aquarius Data Release V2.0 Validation Analysis
Lagerloef, G. and Kao, H-Y. (17-Apr-13). The Aquarius project released V2.0 data in February 2013. This was the first release to have an accompanying validation analysis based on in situ data, along with other supporting documents, whereas previous versions V1.X were for "evaluation" only.

Aquarius Level 2 Algorithm: Recent Developments
Meissner, T., Hilburn, K., Wentz, F., and Scott, J. (16-Apr-13). The Aquarius L-band radiometer/scatterometer system is designed to provide monthly salinity maps at 150 km spatial scale to an accuracy of 0.2 psu. The sensor was launched on June 10, 2011, aboard the Argentine CONAE SAC-D spacecraft. The L-band radiometers and the scatterometer have been taking science data observations since August 25, 2011.

Aquarius Mission Status
Lagerloef, G. (15-Apr-13). The nominal 3-year mission began 1 Dec 2011 and is scheduled to end 30 Nov 2014 (now almost half-way). An additional 3+ months data were obtained during the commissioning phase (25 Aug - 30 Nov 2011).

Aquarius' CAP Ocean Surface Salinity and Wind Products and Their Applications to Water Cycle Research
Yueh, S., Tang, W., Fore, A., Hayashi, A., Lee, T., Lagerloef, G., Bindlish, R., Jackson, T., Murty, V., and Papa, F. (16-Apr-13). Aquarius is a combined passive/active L-band microwave instrument developed to map the sea surface salinity (SSS) field from space. This paper describes Aquarius' version-2.0 (V2.0) Combined Active-Passive (CAP) retrieval algorithm for simultaneous retrieval of surface salinity and wind.

Characterization and Correction of the Aquarius TB Drift Using On-Earth References
Misra, S. and Brown, S. (16-Apr-13). Previous high frequency microwave radiometers such as TOPEX, Jason-1, and Jason-2 have all utilized external brightness temperature references as calibration targets. Global mean brightness temperature measurements (or vicarious cold brightness temperatures) from the ocean are used to calibrate the instrument at one end of the temperature spectrum and hot targets such as the Amazonian rainforests are used at the other end of the temperature spectrum.

CNES Ocean Program
Lambin, J. (15-Apr-13). Latest news from the CNES ocean program, CNES participation and recent developments (SMOS), and future plans and conclusions.

Comparison of Aquarius Sea Surface Salinity With Argo Near-Surface Salinity
Drucker, R. and Riser, S. (16-Apr-13). We compared Aquarius level-2 V1.3.9 sea surface salinities (SSS) with near-surface salinities from Argo floats for a period of 15 months. For this period, near-surface salinites were collected from all delayed-mode Argo profiles worldwide. Approximately 11,000 profiles occurred within the Aquarius footprint within ±24 hours of acquisition. After filtering for various contaminations, approximately 8700 data pairs remained for direct comparison. Results and conclusions from these comparisons will be presented.

DOMECair Campaign, Antarctica, January 2012
Skou, N., Kristensen, S., and Soebjaerg, S. (15-Apr-13). ESA's SMOS mission is faced with the challenging task of measuring the salinity of the oceans as well as the soil moisture over the continents, based on radiometric measurements of the natural emission from Earth. This is done using a microwave radiometer system operating in the protected radio astronomy band near 1.4 GHz (L-band).

Estimates of Observational Errors Related to Small-Scale Horizontal and Vertical Variability in Salinity Fields
Vinogradova, N. and Ponte, R. (17-Apr-13). One of the challenges in collecting and comparing satellite and in situ data is the mismatch in their spatial coverage and the depth of sampling. In this study, we quantify how much of a difference is expected between in situ and satellite measurements of sea-surface salinity (SSS) in the presence of small-scale horizontal variability and near-surface vertical stratification.

Evaluation of Sea Surface Salinity Observed by Aquarius and SMOS
Abe, H. and Ebuchi, N. (17-Apr-13). Sea surface salinity (SSS) derived from the Aquarius and SMOS missions were validated using in-situ salinity data focusing on physical process around the sea surface. The Aquarius and SMOS SSSs were collocated with in-situ observations from Argo floats and offshore moored buoys and outputs from ocean optimal interpolation (OI) system and operational ocean assimilation system. In this abstract, results from the comparisons with observations by Argo floats and outputs from the OI system are reported.

Evolution and Application of the SMOS Level 2 Ocean Salinity Ocean Target Transformation (OTT)
Spurgeon, P. (16-Apr-13). Soon after launch it became clear there was a consistent and drifting mismatch between SMOS reconstructed L band sea surface temperatures (TBs) and Level 2 processor forward models, due to temporal changes in the instrument and Level 1 performance.

Far Eastern Pacific Fresh Pool Surface Salinity Variability Observed by SMOS and Aquarius Sensors Over the Period 2010-2012
Reul, N., Alory, G., Maes, C., Illig, S., and Chapron, B. (17-Apr-13). The seasonal and interannual variability of the Sea Surface Salinity (SSS) deduced from SMOS and Aquarius-SAC-D satellite missions are analyzed over the period 2010-2012 in the Far Eastern Pacific Fresh Pool. The lowest values of salinity in surface layers (±33) in the tropical Pacific Ocean are found in this region of intense precipitation, associated with the northward migration of the Intertropical Convergence Zone (ITCZ) over Central America.

From SMOS to Aquarius and Beyond
Kerr, Y., Cabot, F., Leroux, D., Rougé, B., and Albitar, A. (15-Apr-13). The SMOS (Soil Moisture and Ocean Salinity) satellite was successfully launched in November 2009. This ESA led mission for Earth Observation is dedicated to provide soil moisture over continental surface (with an accuracy goal of 0.04 m3/m3) and ocean salinity. These two geophysical features are important as they control the energy balance between the surface and the atmosphere.

Inter-Calibration Working Group
Le Vine, D. (15-Apr-13). This working group aims toward a merged and validated data product. Initial work will concentrate on solving several key common geophysical modelling issues related to galaxy, roughness, emissivity, ascending-descending biases, RFI, etc., as well as direct inter-calibration of brightness temperatures and salinity products.

Intercalibration of SMOS and Aquarius Over Land, Ice and Ocean
Cabot, F., Kerr, Y., Lagerloef, G., and Anterrieu, E. (15-Apr-13). SMOS mission has celebrated 3 years in orbit in early November 2012. Throughout these 3 years, it has been made clear that final quality of the geophysical retrieved products, both over land and ocean, highly depends on the brightness temperature map quality.

Intercomparison of Aquarius and SMOS Brightness Temperature Observations
Bindlish, R., Jackson, T., Zhao, T., Lagerloef, G., Le Vine, D. Yueh, S., and Kerr, Y. (15-Apr-13). A comparison is reported of Aquarius and SMOS brightness temperatures over land and ocean.

Investigating the Temporal Variability in Salinity from Ascending and Descending Passes in SMOS and Aquarius
Banks, C., Gommenginger, C., Srokosz, M., and Snaith, H. (16-Apr-13). The launch of the SMOS and Aquarius satellites marked a new era in satellite oceanography allowing routine monitoring of the salinity of the world's oceans on synoptic scales. However, there are significant issues affecting the performance of SMOS related to the satellite direction (ascending/descending passes) although the magnitude has decreased with revised versions of the processor.

L-Band Brightness Temperature at Dome-C Antarctica: Intercomparison Between DOMEX-3, SMOS and Aquarius Data
Macelloni, G., Brogioni, M., Pettinato, S., Monti, F., and Casal, T. (15-Apr-13). With the purpose of evaluating the brightness temperature long-time temporal stability of a possible SMOS external calibration reference target an experimental activity, called DOMEX, was carried out in the past years at the Italian-French base of Concordia (Antarctica).

Long and Short Term Stability of SMOS Measurements With NIR Front-end Models
Kainulainen, J., Colliander, A., Martin-Neira, M., and Hallikainen, M. (16-Apr-13). The Soil Moisture and Ocean Salinity (SMOS) satellite has measured the L-band brightness temperature of the Earth over three years. The payload instrument MIRAS (Microwave Imaging Radiometer using Aperture Synthesis) measures two-dimensional brightness temperature maps of the L-band radiation by means of interferometry in order to obtain a reasonable angular resolution.

NASA Earth Science Division Physical Oceanography Program Update
Lindstrom, E. (15-Apr-13). Powerpoint presentation on the Ocean Salinity Program at NASA.

New Reconstruction Algorithms for the Improvement of SMOS L1c Images: Preliminary Results
Turiel, A. and Gonzalez, V. (16-Apr-13). Due to its interferometric design, the direct measurements by SMOS payload, MIRAS, are the visibilities of the signal defined on an hexagonal grid. The visibility field can be expressed as the Fourier transform of brightness temperature in real space modulated by the antenna gain pattern. Retrieving brightness temperatures (the actual physical variable of interest) from visibilities requires to implement an appropriate reconstruction algorithm.

NOAA In Situ - Satellite Blended Analysis of Sea Surface Salinity: Preliminary Results for 2010 - 2012
Xie, P., Boyer, T., Bayler, E., Xue, Y., Byrne, D., Reagan, J., Locarnini, R., Sun, F., Joyce, R., and Arun, K. (17-Apr-13). A technique has been developed to produce analyses of sea surface salinity over the global ocean through blending information from in situ measurements and satellite retrievals.

Ocean Eddy Freshwater Flux
Gordon, A.L. and Giulivi, C.F. (17-Apr-13). Improved in situ and remote sensing observational tools, along with high resolution models, allow us to ask the question (which we have a chance to answer): What role does the ocean mesoscale play in compensating the air-sea flux of heat and freshwater?

Ocean Reference for SMOS Zero-Baselines Based on Aquarius Brightness Temperature Simulator
Colliander, A., Dinnat, E., Le Vine, D., Chae, C-S., and Kainulainen, J. (16-Apr-13). SMOS and Aquarius are ESA and NASA missions, respectively, to make L-band measurements from the Low Earth Orbit.

Ocean Surface Salinity Features as Observed by SMOS and Aquarius
Liu, W.T. and Xie, X. (17-Apr-13). One year of coincident observations of ocean surface salinity by Argo, SMOS, and Aquarius are compared in their identifications of the temporal and spatial characteristics of major ocean features. In the Circumpolar Current, neither SMOS nor Argo shows any seasonal variation of surface salinity, but Aquarius shows a summer peak and a winter low.

Rain-Induced Ocean Surface Salinity Gradients
Asher, W., Jessup, A., Branch, R., and Clark, D. (16-Apr-13). Salinity gradients in the top few meters of the ocean surface can exist due to precipitation or evaporation. If present, they will complicate comparing salinity measured by ARGO drifters at typical depths of five meters to salinities retrieved using L-band microwave radiometers such as SMOS and Aquarius, whose measurement depths are on order of 0.01 m.

Salinity Variability Associated with Changes in the Hydrological Cycle Variables
Sato, O. and Polito, P. (17-Apr-13). As the western boundary current in the South Atlantic subtropical gyre, the Brazil Current transports warm and salty water southward while the Malvinas Current carries colder and fresher water northward. The excursions of the Brazil Current over the southern limit of the gyre brings saltier water to that region that could undergo to intensive cooling and subsequent subduction due to loss of buoyancy.

Sea Water Permittivity Model and Differences in Sea Surface Salinity Retrieved from SMOS and Aquarius
Dinnat, E. and Le Vine, D.M. (16-Apr-13). The ESA Soil Moisture and Ocean Salinity (SMOS) mission and the NASA Aquarius instrument share the common scientific objective of mapping the global Sea Surface Salinity. To that end, they both use radiometers at L-band to measure microwave emission from the sea surface.

SMOS & Aquarius Workshop
Mecklenburg, S. (15-Apr-13). Overview and objectives of the 2013 SMOS & Aquarius Science workshop.

SMOS and Aquarius Salinity Measurements and Validation in the Indian Ocean
Bulusu, S., Nyadjro, E., and Felton, C. (17-Apr-13). The non-availability of global-scale salinity observations has been a challenge in many studies that require salinity data. The Aquarius salinity mission is currently providing complete global coverage of sea surface salinity (SSS) measurements with a temporal resolution of 7 days. In this study, we assess the validity of preliminary Aquarius salinity measurements in the Indian Ocean.

SMOS and In Situ Salinity: Rain and Near-Surface Vertical Stratification Effects
Boutin, J., Hernandez, O., Reverdin, G., Gaillard, F., Reul, N., Martin, N., and Morisset, S. (16-Apr-13). The ESA/SMOS (European Space Agency/Soil Moisture and Ocean Salinity) satellite mission provides new measurements of the Sea Surface Salinity (SSS) using L-band interferometric radiometry since end of 2009. It is the first time that this technology is used for measuring SSS from space, providing global ocean coverage every 3 to 5 days and a spatial resolution of up to 40km.

SMOS Instrument Performance and Calibration After Three Years in Orbit
Martín-Neira, M., Corbella, I., Torres, F., Kainulainen, J., Olivia, R., Closa, J., Cabot, F., Castro, R., Barbosa, J., Gutierrez, A., Anterrieu, E., Tenerelli, J., Martín-Porqueras, F., Buenadicha, G., Delwart, S., Crapolicchio, R. (15-Apr-13). ESA's Soil Moisture and Ocean Salinity (SMOS) mission has been in orbit for already over 3 years which has allowed the calibration and data processing team consolidating both the calibration strategy and the Level-1 processor which transforms the raw visibility samples into polarimetric brightness temperature images.

SMOS Mission Status from the Ocean's Perspective
Reul, N. and SMOS Team Members (15-Apr-13). In this talk, the authors present an overview of the SMOS mission status with respect to oceanic observations.

SMOS Reveals the SSS Signature of Indian Ocean Dipole Events
Durand, F., Alory, G., and Reul, N. (17-Apr-13). The Indian Ocean Dipole (IOD) is the dominant mode of interannual climate variability in the equatorial Indian Ocean. It consists of a basin-scale modification of the upper ocean thermal structure, associated with drastic changes in the rainfall patterns.

Surface Stratification Working Group
Boutin, J. (15-Apr-13). A presentation by the Surface Stratification Working Group at the 2013 SMOS & Aquarius Science Workshop in Brest, France.

The Detectable Errors in Aquarius from Inter-Beam Comparisons
Kao, H-Y. and Lagerloef, G. (16-Apr-13). The Aquarius instrument is designed to use three horns to measure the sea surface salinity (SSS) at the same time. Taking the advantages of this particular design, here we compare the SSS in three beams and attempt to identify the signal and noise within.

Towards an Improved Characterization of Instrumental Biases and Galactic Modeling for SMOS Observations Over the Ocean
Gourrion, J., Tenerelli, J., and Sébastien, G. (16-Apr-13). The Soil Moisture and Ocean Salinity (SMOS) satellite was launched on November 2, 2009 in the framework of the European Space Agency's (ESA's) Earth Explorer opportunity missions. Over the oceans, Sea Surface Salinity (SSS) is retrieved on a global basis with a spatio-temporal sampling appropriate for Ocean dynamics and Earth water cycle studies (Font 2010).

Upper Ocean Profiles of Surface Salinity from the Air-Sea Interaction Profiler
Ward, B., Sutherland, G., ten Doeschate, A., Reverdin, G. and Font, J. (16-Apr-13). Measurements of upper ocean in-situ salinity were conducted during the STRASSE and MIDAS campaigns, which are contributions to the SPURS salinity experiment. Both of these cruises were conducted in the Sub-Tropical North Atlantic in a strong evaporative region.

Upper Ocean Salinity Stratification: Challenges to Validate Satellite Remotely Sensed Sea Surface Salinity
Chao, Y. and Zhang, H. (16-Apr-13). Validating satellite remote sensing data against in situ measurements is always a complex task.

Upper Ocean Stratification from Filters for SMOS/Aquarius Cal-Val
Reverdin, G., Reverdin, G., Boutin, J., Martin, N., Kolodziejczyk, N., Gaillard, F., Rolland, J., and Blouch, P. (16-Apr-13). Since 2005, we have deployed SVP-BS drifters and attached floats to measure ocean temperature and salinity at different depths within the top 60 cm layer in order to provide information for calibrating and validating new L-band radiometer satellite data.

Validation of SMOS and Aquarius Salinity Data in the Agulhas Region
Button, N. and Subrahmanyam, B. (17-Apr-13). Western boundary currents are important to study because they influence regional climates and may impact climate change. The Agulhas Current, in particular, is vital to transport of heat and salt from the Indian Ocean to the Atlantic, especially through Agulhas rings. In order to better understand and assess the role of these rings in the global climate system, accurate measurements of the salinity within the current must be made.