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The Experts below are selected from a list of 16305 Experts worldwide ranked by ideXlab platform

Stephen C Riser – 1st expert on this subject based on the ideXlab platform

  • validation of aquarius sea surface salinity with Argo analysis of error due to depth of measurement and vertical salinity stratification
    Journal of Geophysical Research, 2014
    Co-Authors: Robert Drucker, Stephen C Riser

    Abstract:

    We validate Aquarius sea surface salinities against Argo 1–7 m salinities for the period 27 August 2011 through 1 October 2013, a period of ∼25 months. The validation consists of comparison of 20,149 collocated Argo/Aquarius data pairs. The global mean of the difference between Aquarius and Argo salinities  is +0.018 PSU, with latitudinal variations of approximately ±0.2 PSU. The standard deviation of this difference ranges from about 0.3 PSU in the tropics to 0.7 PSU at high latitudes. We discuss errors due to geographic and temporal displacement and depth of measurement and show that these are insignificant for global validation of Aquarius. In particular, we use NASA’s Tropical Rainfall Measuring Mission 3B42 product to analyze the contribution of vertical salinity stratification in the ocean to validation error. This salinity stratification is important for understanding the hydrological cycle of the oceans and has been cited as a potential source of error in validation of satellite-based sea surface salinity because of the ∼1–7 m minimum depth of most Argo profiles. We show evidence of heavy precipitation events causing stratification greater than 0.1 PSU and lasting ∼2–8 h, but note that these events occur infrequently and contribute less than 0.03 PSU bias in the tropics and 0.025 PSU globally. It is demonstrated that the existing global Argo array provides sufficient data for large-scale validation of Aquarius sea surface salinity. We also discuss the potential to exploit large salinity gradients in the upper mixed layer as a signature of rain in the tropical ocean.

  • the Argo project global ocean observations for understanding and prediction of climate variability
    Oceanography, 2000
    Co-Authors: Dean Roemmich, Silvia L Garzoli, Russ E Davis, Stephen C Riser, W B Owens, Robert L Molinari, Gregory C Johnson

    Abstract:

    Abstract : Phase 1 (9/99 – 9/02) and Phase 2 (7/00 – 6/02) of US Argo provided a total of 187 CTD profiling floats in the Pacific, Atlantic and Indian Oceans. Objectives were to demonstrate technological capabilities for fabrication and for deployment of float arrays in remote ocean locations (Phase 1) and to demonstrate the capability for manufacture and deployment of large float arrays (Phase 2). Recent technology developments in profiling floats were also implemented, including new generation salinity sensors, improved depth capability, and deployment techniques using fast ships and aircraft. Development of the U.S. Argo Data System was part of Phase 1, on a collaborative basis with international partners. Objectives are to make all Argo data publicly available within a day of collection, applying automated quality control procedures consistent with international Argo practices. Data appropriate for research applications and for comparison with climate change models are not available for several months since they need quality control by salinity experts and evaluation of data over many (10 day) float cycles. Phase 3 is a 5-year project (8/01 – 6/06) including full implementation of the US component of Argo. This report includes Phase 3/Year 2, which deployed 290 CTD profiling floats during CY2003 plus support for these deployments, data management activities and for national and international coordination of Argo. Float deployments targeted the Atlantic, Pacific, Indian, and Southern Oceans. Priorities for US float deployment are set by the US Argo Advisory Panel.

Jacqueline Boutin – 2nd expert on this subject based on the ideXlab platform

  • Sea surface freshening inferred from SMOS and Argo salinity: Impact of rain
    Ocean Science, 2013
    Co-Authors: Jacqueline Boutin, N. Martin, Gilles Reverdin, Xin Yin, Fabrice Gaillard

    Abstract:

    The sea surface salinity (SSS) measured from space by the Soil Moisture and Ocean Salinity (SMOS) mission has recently been revisited by the European Space Agency first campaign reprocessing. We show that, with respect to the previous version, biases close to land and ice greatly decrease. The accuracy of SMOS SSS averaged over 10 days, 100 × 100 km2 in the open ocean and estimated by comparison to Argo (Array for Real-Time Geostrophic Oceanography) SSS is on the order of 0.3–0.4 in tropical and subtropical regions and 0.5 in a cold region. The averaged negative SSS bias (−0.1) observed in the tropical Pacific Ocean between 5° N and 15° N, relatively to other regions, is suppressed when SMOS observations concomitant with rain events, as detected from SSM/Is (Special Sensor Microwave Imager) rain rates, are removed from the SMOS–Argo comparisons. The SMOS freshening is linearly correlated to SSM/Is rain rate with a slope estimated to −0.14 mm−1 h, after correction for rain atmospheric contribution. This tendency is the signature of the temporal SSS variability between the time of SMOS and Argo measurements linked to rain variability and of the vertical salinity stratification between the first centimeter of the sea surface layer sampled by SMOS and the 5 m depth sampled by Argo. However, given that the whole set of collocations includes situations with Argo measurements concomitant with rain events collocated with SMOS measurements under no rain, the mean −0.1 bias and the negative skewness of the statistical distribution of SMOS minus Argo SSS difference are very likely the mean signature of the vertical salinity stratification. In the future, the analysis of ongoing in situ salinity measurements in the top 50 cm of the sea surface and of Aquarius satellite SSS are expected to provide complementary information about the sea surface salinity stratification.

  • sea surface freshening inferred from smos and Argo salinity impact of rain
    Ocean Science, 2012
    Co-Authors: Jacqueline Boutin, N. Martin, Gilles Reverdin, Fabienne Gaillard

    Abstract:

    The sea surface salinity (SSS) measured from space by the Soil Moisture and OceanSalinity (SMOS) mission has recently been revisited by the European Space Agencyfirst campaign reprocessing. We show that, with respect to the previous version, biases close to land and ice greatly decrease. The accuracy of SMOS SSS averaged over 105days 100×100 km2in the open ocean and estimated by comparison to Argo SSS is on the order of 0.3–0.4 in tropical and subtropical regions and 0.5 in a cold region. Themean SSS−0.1 bias observed in the Tropical Pacific Ocean between 5◦N and 15◦N, relatively to other regions, is suppressed when SMOS rainy events, as detected on SSM/Is rain rates, are removed from the SMOS-Argo comparisons. The SMOS fresh-10ening is linearly correlated to SSM/Is rain rate with a slope estimated to −0.14 mm−1 h,after correction for rain atmospheric contribution. This tendency is the signature of thetemporal SSS variability between the time of SMOS and Argo measurements linked to rain variability and of the vertical salinity stratification between the first centimeter of the sea surface layer sampled by SMOS and the 5 m depth sampled by Argo. However, given that the whole set of collocations includes situations with rainy Argo measurements collocated with non rainy SMOS measurements, the mean−0.1 bias and the negative skewness of the statistical distribution of SMOS minus Argo SSS difference are very likely the mean signature of the vertical salinity stratification. In the future, the analysis of ongoing in situ salinity measurements in the top 50 cm of 20the sea surface and of Aquarius satellite SSS are expected to provide complementary information about the sea surface salinity stratification.

Dean Roemmich – 3rd expert on this subject based on the ideXlab platform

  • on the future of Argo a global full depth multi disciplinary array
    Frontiers in Marine Science, 2019
    Co-Authors: Dean Roemmich, Kenneth S Johnson, Herve Claustre, Sylvie Pouliquen, Brian A King, Sarah G Purkey, Matthew H Alford, James N Moum, Brechner W Owens, Megan Scanderbeg

    Abstract:

    The Argo Program has been implemented and sustained for almost two decades, as a global array of about 4000 profiling floats. Argo provides continuous observations of ocean temperature and salinity versus pressure, from the sea surface to 2000 dbar. The successful installation of the Argo array and its innovative data management system arose opportunistically from the combination of great scientific need and technological innovation. Through the data system, Argo provides fundamental physical observations with broad societally-valuable applications, built on the cost-efficient and robust technologies of autonomous profiling floats. Following recent advances in platform and sensor technologies, even greater opportunity exists now than 20 years ago to (i) improve Argo’s global coverage and value beyond the original design, (ii) extend Argo to span the full ocean depth, (iii) add biogeochemical sensors for improved understanding of oceanic cycles of carbon, nutrients, and ecosystems, and (iv) consider experimental sensors that might be included in the future, for example to document the spatial and temporal patterns of ocean mixing. For Core Argo and each of these enhancements, the past, present, and future progression along a path from experimental deployments to regional pilot arrays to global implementation is described. The objective is to create a fully global, top-to-bottom, dynamically complete, and multidisciplinary Argo Program that will integrate seamlessly with satellite and with other in situ elements of the Global Ocean Observing System (Legler et al., 2015). The integrated system will deliver operational reanalysis and forecasting capability, and assessment of the state and variability of the climate system with respect to physical, biogeochemical, and ecosystems parameters. It will enable basic research of unprecedented breadth and magnitude, and a wealth of ocean-education and outreach opportunities.

  • Argo the challenge of continuing 10 years of progress
    Oceanography, 2009
    Co-Authors: Dean Roemmich, M Belboch, Howard J Freeland, Silvia L Garzoli, John W Gould, Fiona Grant, M Ignaszewski, Birgit Klein, P Le Y Traon, Brian A King

    Abstract:

    In only 10 years, the Argo Program has grown from an idea into a functioning global observing system for the subsurface ocean. More than 3000 Argo floats now cover the world ocean. With these instruments operating on 10-day cycles, the array provides 9000 temperature/salinity/depth profiles every month that are quickly available via the Global Telecommunications System and the Internet. Argo is recognized as a major advance for oceanography, and a success for Argo‘s parent programs, the Global Ocean Data Assimilation Experiment and Climate Variability and Predictability, and for the Global Earth Observation System of Systems. The value of Argo data in ocean data assimilation (ODA) and other applications is being demonstrated, and will grow as the data set is extended in time and as experience in using the data set leads to new applications. The spatial coverage and quality of the Argo data set are improving, with consideration being given to sampling under seasonal ice at higher latitudes, in additional marginal seas, and to greater depths. Argo data products of value in ODA modeling are under development, and Argo data are being tested to confirm their consistency with related satellite and in situ data. Maintenance of the Argo Program for the next decade and longer is needed for a broad range of climate and oceanographic research and for many operational applications in ocean state estimation and prediction.

  • the 2004 2008 mean and annual cycle of temperature salinity and steric height in the global ocean from the Argo program
    Progress in Oceanography, 2009
    Co-Authors: Dean Roemmich, John Gilson

    Abstract:

    Abstract The Argo Program has achieved 5 years of global coverage, growing from a very sparse global array of 1000 profiling floats in early 2004 to more than 3000 instruments from late 2007 to the present. Using nearly 350,000 temperature and salinity profiles, we constructed an upper-ocean climatology and monthly anomaly fields for the 5-year era, 2004–2008. A basic description of the modern upper ocean based entirely on Argo data is presented here, to provide a baseline for comparison with past datasets and with ongoing Argo data, to test the adequacy of Argo sampling of large-scale variability, and to examine the consistency of the Argo dataset with related ocean observations from other programs. The Argo 5-year mean is compared to the World Ocean Atlas, highlighting the middle and high latitudes of the southern hemisphere as a region of strong multi-decadal warming and freshening. Moreover the region is one where Argo data have contributed an enormous increment to historical sampling, and where more Argo floats are needed for documenting large-scale variability. Globally, the Argo-era ocean is warmer than the historical climatology at nearly all depths, by an increasing amount toward the sea surface; it is saltier in the surface layer and fresher at intermediate levels. Annual cycles in temperature and salinity are compared, again to WOA01, and to the National Oceanography Center air–sea flux climatology, the Reynolds SST product, and AVISO satellite altimetric height. These products are consistent with Argo data on hemispheric and global scales, but show regional differences that may either point to systematic errors in the datasets or their syntheses, to physical processes, or to temporal variability. The present work is viewed as an initial step toward integrating Argo and other climate-relevant global ocean datasets.