GODAE is sponsored by
List of poster abstracts
[A-B] [C-E] [F-G] [H] [I-K] [L] [M-O] [P-R] [S] [T-W] [X-Z]
Authors C - E
Number 113 - Session 5
Regional activities in MERCATOR-OCEAN: toward a regional operational system on the IBI domain
1S. Cailleau, 1J. Chanut,1B. Levier, 1G. Reffray
1Mercator Ocean, Toulouse, France
Abstract
Recent efforts have been made in regional modelling at Mercator Ocean with the aim to operate a regional system covering the IBI area in the future (contribution of My Ocean project). In this way, the NEMO model has been improved by adding high frequency forcings (tides, 3-hourly meteorological fields permitting to resolve the diurnal cycle among other and the dynamics induced by the rivers discharges on the shelf), physical parameterizations permitting to resolve processes occurring at regional scale (improvements on the vertical physics, improvements on the physics at the surface and bottom layers, etc ?) and new numerical schemes (advection, OBC, etc?).
This "regional" version of NEMO has been tested in a first configuration covering the Bay of Biscay in the framework of a model inter-comparison study. The other concerned models are SYMPHONIE (POC CNRS), HYCOM (SHOM) and MARS3D (IFREMER). For each model, a realistic run of the entire year 2004 has been carried out with the same bathymetry, the same tidal, meteorological and rivers forcings and the same OGCM fields used to initialize and force the open boundaries.
The results are studied through a complete battery of tests. In the first part of them, the established diagnostics focus on the capability of each model to conserve the water properties (water masses, heat content, SST bias etc ?). In the second part, the capability of each model to reproduce physical processes (Ushant front, warmpool, rivers plume etc?) is underlined.
Number 136 - Session 4
SHALLOW STRATIFICATION OF THE NORTHERN OCEANS: AN EVALUATION OF NINE ANALYSES
J.A. Carton1, G.A. Chepurin1, and Y.-S. Chang2
1Department of Atmospheric and Oceanic Science, University of Maryland College Park, MD USA
2Geophysical Fluid Dynamics Laboratory, Princeton, NJ USA
Abstract
Here we apply a set of nine ocean analyses spanning part or all of the period 1960-2002 to the examination of decadal changes in the stratification of the upper layers of these northern and tropical oceans following a previous examination of heat content in many of these same analyses (Carton and Santorelli, 2008). The analyses can be divided by estimation technology into four types. We examine one 'no-model' analysis, UK-OI1, constructed by objectively analyzing the historical profile observation set assuming a climatological first guess. We examine six analyses constructed using sequential estimation techniques with an ocean general circulation model to provide a first guess: CERFACS2 , GODAS3 , ECMWF4 , INGV5 , SODA6, and UK-FOAM7 . An additional analysis, GECCO8 , is constructed using both an ocean general circulation model and its adjoint in a 4DVar approach, adjusting initial conditions and surface forcings. Finally, we include the GFDL9, a coupled analysis which applies the sequential approach to the atmosphere and ocean simultaneously with forecast models for each. Our analysis focuses on representation of mixed layer year-to-year variability as well as on the representation of upper ocean water masses as represented on constant density surfaces 24.5σ, 25.5σ, and 26.5σ). Consistency with the observations is evaluated by comparison to a set of 38,000 CTD casts, many of which will have been assimilated, and by comparison to published studies of year-to-year changes in water properties. The results are organized by basin and by water mass.
In the North Pacific the time mean depth of the 24.5σ surface reaches a maximum of 200m in the northwestern tropical Pacific, shallowing to less than 50m north of 30°N as well as in eastern Pacific, and also shallowing in a narrow band of latitudes along a ridge in the thermocline at 10°N . This density surface lies close to the top of two water masses --North Pacific Subtropical Mode Water (with densities ranging from σ = 24.5-25.9) and North Pacific Eastern Subtropical Mode Water (σ = 24-25.4) according to Bingham and Suga (2006). In many analyses the 24.5σ surface is <10m too shallow in the west and <10m too deep in the east. One exception is GECCO, which is 10-30m too deep throughout the subtropics. ECMWF, GFDL, and GODAS are too fresh in the north while GECCO and SODA are too salty. In general the analyses are able to reproduce the seasonal deepening of the mixed layer, but many have difficulty reproducing the observed distribution of seasona barrier and compensation layers due to errors in the salinity fields.
The subtropical mode water masses in the North Pacific are shown to exhibit decadal variability reminiscent of that reported in Miller and Schneider (2000) (this study was based on the White, 1996 XBT analysis) in which anomalies in the depth of the 25.5σ surface are shown to migrate clockwise around the basin with timescales of a decade. However an examination of temperature, salinity, and potential vorticity suggests that the processes controlling these decadal anomalies remain obscure. In particular, examination of the thermocline response to a multi-year freshwater flux anomaly, documented at Hawaii by Lukas (2001), suggests that these ocean analyses are in need of significant improvements to their handling of the freshwater cycle.
2 Instituto Nazionale di Geofisica e Volcanologia, Bellucci et al. (2007)
3 National Centers for Environmental Prediction Global Ocean Data Assimilation, Behringer (2005)
4 European Centre for Medium Range Weather Forecasts, Balmaseda et al. (2007)
5 The European Centre for Research and Advanced Training in Scientific Computation, Davey (2005)
6 Simple Ocean Data Assimilation, Carton and Giese (2007)
7 United Kingdom Forecasting Ocean Assimilation Model, Bell (2000) and Bell et al. (2004)
8 Global Estimation of Circulation and Climate Experiment, Kohl and Stammer (2008)
9 Geophysical Fluid Dynamics Laboratory, Chang et al. (2008)
Number 131 - Session 4
THE GODAE HIGH RESOLUTION SST LONG TERM STEWARDSHIP
AND REANALYSIS FACILITY AT THE US NODC
Kenneth S. Casey and Tess Brandon
NOAA National Oceanographic Data Center, Silver Spring MD, 20910, USA
Abstract
The Long Term Stewardship and Reanalysis Facility (LTSRF) at NOAA's National Oceanographic Data Center (NODC) serves as the perpetual archive and coordinating center for reanalysis activities for the GODAE High Resolution Sea Surface Temperature Pilot Project (GHRSST-PP). Initial discussions beginning in 2002 led to formal operations in 2006. Since that time, automated archive operations at the GHRSST LTSRF have been successfully maintained with nearly 100% reliability and data volumes in the archive growing to over 13 terabytes by June of 2008. Each day, approximately 1000 netCDF files and over 25 gigabytes are brought into the archive from a variety of satellite sensors and product development systems. These include regional and global Level 4 (L4) analyses and Level 2 Preprocessed (L2P) data for nearly all satellite sensors capable of observing SST, including the AVHRR, AATSR, TMI, AMSR-E, SEVIRI, MODIS, and GOES. User accesses have also been growing rapidly, from 0.3 GB and 28 netCDF files/day in 2006 to 6.2 GB and 1444 netCDF files/day in 2008.
Extensive progress has also been made in meeting the two primary goals of GHRSST reanalsysis: to develop with the international community a suite of improved reanalysis climate data records for SST and to connect these modern primarily satellite-based SST analyses with the longer time series of ship-based SST reconstructions. A new SST intercomparison facility at the LTSRF, built in association with the Global Climate Observing System (GCOS) SST and Sea Ice Working Group, enables users to easily and rapidly compare numerous historical ship-based SST reconstructions, in situ and satellite input data sets, and modern satellite-in situ blended SST analysis products. All of the various datasets and analyses have been transformed to common space-time grids and made available in both Matlab and GHRSST L4 netCDF formats along with a set of intercomparison statistics. This intercomparison framework brings into the GHRSST Reanalysis community the GCOS talent and experience and is enabling significant progress toward developing authoritative long term-records for SST.
Number 134 - Session 5
A COUPLED OCEAN-ATMOSPHERE MODELING SYSTEM FOR TROPICAL CYCLONE STUDIES
H. R. Winterbottom 1,2, E. P. Chassignet 1, and C. A. Clayson 2,3
1Center for Ocean-Atmosphere Prediction Studies, The Florida State University, Tallahassee, FL, USA
2Department of Meteorology, The Florida State University, Tallahassee, FL, USA
3Geophysical Fluid Dynamics Institute, The Florida State University, Tallahassee, FL, USA
Abstract
The majority of numerical weather prediction models employed for tropical cyclones focus largely on track and intensity forecasting, while relying on convective and planetary boundary-layer parameterization schemes which are often adjusted for mid-latitude weather phenomena. As a result, the respective forecast for a tropical cyclone is largely determined by inaccuracies in both the planetary boundary layer and convection. Further, with the increasing demand of coupled ocean-atmosphere models for tropical cyclone forecasting, the impact of these deficiencies in the physical parameterizations becomes even more glaring.
A collaborative effort between the Center for Ocean-Atmosphere Prediction Studies and the Department of Meteorology at the Florida State University has resulted in the development of a coupled ocean-atmosphere modeling system, specifically designed to study and understand the air-sea interactions and PBL processes within tropical cyclones. The ocean model is HYCOM (Bleck, 2002; Chassignet et al., 2003; Halliwell, 2004) and the atmospheric model is the second generation of the Weather Research and Forecasting (WRF) Advanced Research WRF (ARW) model (Michalakes et al. 2004). The coupled forecast system will couple the ocean and atmospheric models via the Model Coupling Toolkit (MCT) and a wave model parameterization will be used when computing the fluxes. The results of this effort will be a fully-coupled modeling system able to address both the deficiencies of the current physical parameterizations as well exploring other air-sea interaction phenomena such as sea-spray, the impacts of warm-cored eddies of varying sizes and structures, and the structure of cold wakes resulting from tropical cyclone passage. Initial results from these experiments will be presented.
An experimental, near real-time version of this coupled-model system ? with an ocean initial state derived from the 1/12 degree global HYCOM and forced with hourly atmospheric fields derived from the most recent 30-km WRF-ARW, is provided daily for the North Atlantic Ocean basin. When a tropical cyclone is present in the basin, data assimilation procedures are applied to specify a synthetic vortex which is more closely in agreement with the most current observations for the tropical cyclone. The data assimilation procedures include the use of an improved planetary boundary layer wind specification and tropospheric thermodynamic profiles derived from Global Positioning System (GPS) Radio Occultation (RO) observations within tropical cyclones (Winterbottom and Xiao, 2008).
Number 145 - Session 4
Implementation of a reduced-rank,
square-root smoother for ocean data assimilation
E. Cosme1, J.-M. Brankart1, J. Verron1, P. Brasseur1, M. Krysta1, 2
1LEGI, CNRS/Universit´e de Grenoble, Grenoble, France
2LJK, CNRS/Universit´e de Grenoble/INRIA, Grenoble, France
Abstract
Data assimilation is the process by which models and observations are optimally combined to provide a realistic representation of the ocean state. In this regard, the Kalman filter (KF) has received much attention, for it displays properties of optimality under certain assumptions (linearity in the dynamics and gaussian errors in the system, in particular). Due to various obstacles (numerical burden, unknown data assimilation inputs), implementing the KF for oceanic problems requires simplifications. One of them is to apply a square-root decomposition and to reduce the rank of the state error covariance matrix, as it has been done in several GODAE systems.
A specificity of the KF lies in that each analysis product contains the information of earlier and simultaneous observations, but not subsequent observations. However, for some specific problems such as reanalyses making, subsequent observations exist and may be advantageously used for the estimation process. Under the same assumptions as for the KF, this retrospective estimation is performed by optimal smoothers.
The poster will report the theoretical derivation, the technical implementation, and an illustrative application of a reduced-rank, square-root smoother based on the Singular Evolutive Extended Kalman (SEEK) filter, a proxy of which is currently in use for operational oceanography within the French MERCATOR project. The application is performed with a high-resolution (1/4°) Ocean General Circulation Model in an idealized, double-gyre configuration. Twin experiments are performed: Pseudo-observations of Sea Surface height (on simulated TOPEX/POSEIDON traces) and temperature (on an idealized ARGO-like network) are extracted from a 1/6° resolution simulation. The smoother, by using subsequent observations in the estimation process of a state, reduces the errors provided by the KF. Figure 1 illustrates this improvement of the KF.
Figure 1: RMS errors in SSH over the whole domain. In black: the standard, jagged, KF error trajectory, alternating forecasts and analyses; in red: smoother results, using observations up to 10 days in the future.
Number 25 - Session 4
Application of a hybrid EnKF-OI to ocean forecasting
F. Counillon
Mohn-Sverdrup center/NERSC, Norway
Abstract
Data assimilation methods often use an ensemble to obtain the background error covariance. Two approaches are commonly used; a simple one with a static ensemble, or a more advanced one with a dynamical ensemble, which is often non-practical due to its high computational requirements. Some recent studies suggested a hybrid covariance, which is a linear combination of the static and the dynamical covariances. Here, the hybrid covariance is extensively tested with a quasi-geostrophic model and with two different analysis schemes, namely the Ensemble Kalman Filter (EnKF) and the Ensemble Square Root Filter (ESRF). For both scheme, the benefits of using hybrid covariances are large for a small number of dynamical members and becomes negligible for a large number of dynamical members. The optimal value of the hybrid blending coefficient appears to decrease exponentially with the number of dynamical member, independently from the scheme used. The hybrid covariance ESRF (ESRF-OI) appears to be more accurate and more stable than that with the EnKF (EnKF-OI), as it avoids sampling noise.
Finally, the capability of a 10 members EnKF-OI is demonstrated for a realistic application of the Gulf of Mexico, and compared to a 10 members EnKF and an ensemble optimal interpolation (EnOI). While the EnKF appears to diverge, the EnKF-OI reduces significantly the forecast error compared to the EnOI, and improves the positions of the fronts.
Number 84 - Session 5
ENVIRONMENTAL AND CLIMATE OCEAN INDICES:
INTERCOMPARISON OF THE FRENCH MERCATOR AND U.S. HYCOM
SYSTEMS
L. Crosnier1, M. Drevillon1, S. Ramos Buarque1, F. Messal1, F. Soulat1
E. Chassignet2, A. Srinivasan2, O.M. Smedstad3, S. Rattan3, and A. Wallcraft3
1Mercator-Ocean,Ramonville St Agne, France
2Center for Ocean-Atmospheric Prediction Studies (COAPS), FSU, Tallahassee, FL,USA
3Naval Research Lab, Stennis Space Center, MS,USA
Abstract
Ocean environmental indices provide information for a better understanding of the oceans and their ecosystems, as well as a simple representation of ocean-climate variability. They also allow, in the best-case scenario, to anticipate the effects of environmental hazards and pollution crises. Mercator Ocean (France) and the HYCOM group (USA) are operating Ocean Forecast System (henceforth OFS) that can analyze and forecast the 3D-ocean state including temperature, salinity and currents at various resolutions.
We present several indices for the state of the ocean among which: an upwelling index based on sea-surface temperature, the Tropical Cyclone Heat Potential showing the thermal energy available in the ocean to enhance or decrease the power of cyclones, the Indian Ocean Dipole Mode Index based on sea-surface temperature, the sea-surface temperature time series in the "Nino boxes", volume transport across various straits and Ocean Heat transport. We compare the results obtained using the Mercator and the HYCOM systems and draw conclusions on the strength of each systems, as well as their potential for providing useful information to end-users.
Number 149 - Session 3
US WEST COAST MODELING USING GODAE PRODUCTS
S. deRada1, J. C. Kindle1, S. Anderson1, I. Shulman1, B. Penta1, J. Olascoaga2
1Naval Research Laboratory, Stennis Space Center, MS 39529, USA
2University of Miami, Miami, FL 33149, USA
Abstract
The paper presents the impact of a diverse set of GODAE products used in ocean modeling research focused on the US West Coast. Both numerical ocean models, NCOM and HYCOM, have been implemented for this region and are coupled to an ecosystem model, providing a valuable test bed for evaluation and comparison of the GODAE atmospheric and remote forcing products used.
Several simulations have been conducted using atmospheric forcing (momentum and heat fluxes) from NOGAPS (1.0°,0.5°) and COAMPS (81,27,9,3 Km), and initial and open boundary conditions from Global NCOM and Global HYCOM, both with and without data assimilation. Evaluating the atmospheric and global ocean products, including sensitivity to resolution, coupling schemes, and numerical techniques for nesting have been an intricate part of the research, with large focus directed to feasibility assessment of the GODAE global ocean products as providers of initial and boundary conditions for regional and coastal models.
The progression of ocean modeling research in the US West Coast region illustrates the evolution of the GODAE products and their impact on regional and coastal modeling. Predictions from the nested ocean models are evaluated and contrasted from their inception, illustrating improvements, and elucidating the added value of data assimilation in the GODAE products. For example, the use of data-assimilative HYCOM for initial and boundary values provide better agreement of observed and model predicted sea surface height.
Number 7 - Session 1
OPERATIONAL OCEANOGRAPHY, INTERGOVERNMENTAL COORDINATION, AND THE ROLE OF JCOMM
Peter Dexter1, Jean-Louis Fellous2, Craig Donlon3, Gary Brassington1, Alice Soares4 and Albert Fischer5
1Bureau of Meteorology, GPO Box 1289, Melbourne 3001, Australia
2COSPAR, c/o CNES, 2 Place Maurice-Quentin, 75039 Paris Cedex 01, France
3The Met Office, Hadley Centre, Fitzroy Road, Exeter, EX1 3PB, United Kingdom
4WMO Secretariat, CP 2300, CH-1211 Geneva 2, Switzerland
5IOC Secretariat, 1 rue Miollis, 75732 Paris Cedex 15, France
Abstract
The Joint WMO/IOC Technical Commission for Oceanography and Marine Meteorology (JCOMM) has, as its mandate, the intergovernmental coordination of the implementation and maintenance of an operational, global, ocean observing (in situ and space-based), data management and services system, in support of the provision of marine services, operational marine meteorology, global climate studies, a range of other service applications, and operational oceanography. As such, JCOMM is recognized as a primary implementation mechanism for global GOOS, and it underpins the World Weather Watch with marine data. It also has developing responsibilities for assisting in the implementation of coastal GOOS. This work is performed with scientific guidance in relation to observing system design and the integration of new advances deriving from the Ocean Observations Panel for Climate, and the new Panel for Integrated Coastal Observations, coordinated through the GOOS Scientific Steering Committee.
JCOMM also has long-standing responsibility for the global regulation and coordination of a range of marine meteorological services in support of maritime safety and coastal hazard warning, and thus has both the expertise and mandate to undertake a similar intergovernmental role for the operational ocean forecast systems deriving from GODAE. This poster will outline the current status of the observing, data management and services systems, the JCOMM coordination and support mechanisms, and implementation plans. The poster will also address important issues such as system performance monitoring and logistics support, the complementary role of research and operational agencies, and the private sector, in systems development, and the need for coordination with related science and technology fields, for improved interoperability.
Number 162 - Session 4
COMPARING AND COMBINING ARGO DATA WITH ALTIMETER DATA
TO DESCRIBE THE VERTICAL STRUCTURE OF THE OCEAN
A.-L. Dhomps1, S. Guinehut1, G. Larnicol1, P.-Y. Le Traon2
1CLS / Space Oceanography Division,, Ramonville Saint-Agne, France
2Ifremer,Technopole de Brest-Iroise, Plouzané,France
Abstract
Studying the ocean's structure greatly depends upon the availability of ocean observations. On the one hand, temperature (T) and salinity (S) profile measurements from Argo profiling floats provide sparse in-situ data, but give precise estimations of the ocean's steric vertical structure every 10 days and for large part of the world ocean. On the other hand, satellite altimetry provides steric and non-steric synoptic observations of the sea level every 7 days and all over the world. Both types of data are needed by climate and operational oceanography and it is necessary to distinguish steric and non-steric components in order to correctly merge altimeter and in-situ data through data assimilation techniques.
Guinehut et al. (2006) analysed the consistency between altimeter and in-situ T/S profiles coming from XBT,
CTD and Argo profiling floats for the 1993-2003 period. Altimeter sea level anomalies (SLA) and hydrographic dynamic height anomalies (DHA) were compared and correspond very well. However, they do have some differences that were studied in order to describe ocean circulation in terms of steric and nonsteric contributions to SLA and to observe the circulation at 700-meter depth.
The Argo dataset is now large enough to pursue Guinehut et al.'s (2006) research with better spatial coverage, a deeper reference level (down to 1000-meter depth), with both temperature and salinity profiles and using data for the 2001-2007 period, which this study was designed to do. AVISO altimeter combined maps are still used as the altimetry component. The new in-situ dataset enables us to have accurate comparisons between SLA and DHA (figure 1), and to better understand the vertical structure of ocean.
Figure 1: Correlation coefficient between SLA and DHA. Reference level for DHA equals to 1000 meters
Number 127 - Session 4
MONTE CARLO STUDY OF WIND FORCING OR PARAMETER ERRORS
IN A COUPLED PHYSICAL - BIOGEOCHEMICAL MODEL
M. Doron, D. Beal, P. Brasseur & J.-M. Brankart
LEGI-MEOM, CNRS, BP 53, 38041 Grenoble cedex 9, France
Abstract
A coupled physical ? biological model is implemented over the North Atlantic (20°S ? 80°N, 98°W ? 23° E), at the resolution 1 / 4°. The physical model NATL4 is a OPA9 / NEMO model implemented in a DRAKKAR configuration (Barnier et al., Ocean Dynamics, 2006). The biogeochemical model LOBSTER is a nitrogen-based ecosystem model including six prognostic variables: phytoplankton, zooplankton, semilabile dissolved organic nitrogen, detritus, nitrate and ammonium (Lévy et al., Journal of Geophysical
Research, 2005) and the coupling is made online. For data assimilation purposes, the sensitivity of the model to the errors in the wind forcing or to the errors in the parameterization of the biogeochemical equations is investigated. Ensemble simulations made with perturbations of the wind forcing (200 members, 30-days) during the spring bloom in March-April 1998 already showed a rather complex ecosystem response. The nature of the response for phytoplankton and zooplankton exhibits often nonlinearities and threshold effects in addition to be region and time dependent. A simple non-linear change of variable (anamorphosis) helps to better exploit the nonlinear correlations. In the case of errors in the parameterization of the biogeochemical model, preliminary simulations with uniform perturbations of three parameters (phytoplankton maximal growth rate, phytoplankton mortality rate and zooplankton grazing rate) show variations of the surface phytoplankton compartment of up to 100% in 6 days for a 50% change in the parameters values (with a single parameter modified, during the spring bloom in 1998). This preliminary study for the sensitivity of the biogeochemical model to the errors in the parameterization will be reinforced by more comprehensive ensemble simulations, where the three parameters are perturbed simultaneously and with space-dependant values. This work is ongoing and the nature of the response will be assessed for the main biogeochemical variables.
Number 96 - Session 3
OCEAN PROPERTIES IN 2007 DESCRIBED BY THE MERCATOR-OCEAN
GLOBAL OCEAN ANALYSIS AND FORECASTING SYSTEM
Drévillon Marie1, Lellouche Jean-Michel1, Greiner Eric2, Verbrugge Nathalie2, Rémy Elisabeth1, Crosnier Laurence3, Benkiran Mounir2, Bourdallé-Badie Romain1, Bricaud Clément3, Derval Corinne1, Drillet Yann3, Durand Edmée3, Ferry Nicolas3, Garric Gilles4, Le Galloudec Olivier3, Parent Laurent3, Tranchant Benoît1, Testut Charles-Emmanuel4
1CERFACS, Toulouse, France
2CLS, Toulouse, France
3Mercator-Océan, Toulouse, France
4MGC, Toulouse, France
Abstract
Since the beginning of GODAE and also in the framework of the European projects MERSEA and now GMES/MyOcean, Mercator-Ocean has been designing a hierarchy of ocean analysis and forecasting systems. These systems are based on numerical models of the ocean and data assimilation systems which interpolate in an optimal way all available observations of the ocean. The real time operation of these systems began in 2001, in order to produce each week realistic 3-dimensional oceanic conditions (temperature, salinity, currents?) two weeks back in time and a two weeks forecast, driven at the surface by atmospheric conditions from the European Center for Medium Range Weather Forecast (ECMWF).
Since April 2008, the state-of-the-art Mercator Ocean forecasting system demonstrates that the use of the ocean and sea ice model NEMO and of the data assimilation system SAM2 (Système d'Assimilation Mercator V2) can produce high quality real time analyses and forecast of the ocean at the global scale, and up to the "eddy resolving" horizontal resolution. This system currently comprises a global ocean configuration at ¼° horizontal resolution and a North Atlantic and Mediterranean zoom at 1/12°, both having 50 levels on the vertical with a surface refinement. Both have been run and comprehensively validated over the year 2007. The realism of the description of the ocean physics, sea ice, water masses, and volume transports is assessed on this poster. Although some biases develop in regions where complex interactions take place between the different limitations of the system (mostly the Antarctic and the tropics), the results show a "qualitative jump" of the physical and statistical skills of the system. They reinforce the scientific feasibility of the future upgrade of the system into a global high resolution configuration at 1/12°.
Corresponding authors e-mail: mdrevillon@mercator-ocean.fr, jlellouche@mercator-ocean.fr
Number 8 - Session 2
GMES SENTINEL-3: A MISSION FOR OPERATIONAL OCEANOGRAPHY
M.R. Drinkwater
European Space Agency-ESTEC, Noordwijk, The Netherlands
Abstract
In the frame of the Global Monitoring for Environment and Security (GMES) programme jointly conceived by the European Space Agency (ESA) and the European Commission, ESA is developing the Sentinel-3 system to respond to the requirements for operational global scale, near-real-time ocean, ice and land monitoring with fast revisit rate and at medium resolution (300 ? 1000m). In order to meet the needs of the operational oceanography user community, the Sentinel-3 satellite data will support the operational generation of a generalised suite of high-level geophysical products, including as priority: sea-surface topography, sea-surface temperature, and ocean colour data. The system has been designed to ensure continuity to existing ENVISAT radar altimetry and multi-spectral Visible and Infrared ocean and land-surface radiance observations of ERS and ENVISAT instrumentation, and includes small enhancements to meet the operational revisit requirements and to facilitate new products and future evolution of services.
The surface topography mission responds to the primary objective of providing accurate, high density altimetry measurements from a high-inclination orbit with long exact repeat cycle, to complement the JASON ocean altimeter series. The altimeter configuration balances continuity and improved performance needs, with a single-antenna radar altimeter with aperture synthesis processing for increased along-track spatial resolution. The altimeter will be supported by a Precise Orbit Determination (POD) system and microwave radiometer (MWR) for correcting accompanying water vapour induced propagation delay errors. The altimeter's additional capabilities include the agility to track over a variety of surfaces: open ocean, coastal sea zones, sea ice and inland waters.
The Ocean and Land Colour Instrument (OLCI) fulfils ocean colour and land surface cover mission objectives and is based on the ENVISAT MERIS instrument. The Sea and Land Surface Temperature Radiometer (SLSTR) in turn supports the ocean and land surface temperature observation requirements, and is based on the ENVISAT AATSR instrument. Unlike AATSR, SLSTR implements a double scanning mechanism for a much larger swath, and allowing for the synergetic use of both OLCI and SLSTR instruments over the broad region of swath overlap.
A reference sun-synchronous orbit at 814 km altitude is presently selected (14+7/27 revolutions per day) with a local equatorial crossing time of 10:00 a.m., as a compromise between optical instrument and altimetry needs. In this orbit configuration two simultaneously-orbiting satellites are required to support full imaging of the oceans in less that 2 days after taking Sun-glint contamination into account, whilst delivering global land coverage in just over 1 day at the equator. The orbit also maximizes complementarity with the NPOESS satellite series.
The Sentinel-3 system is characterised by continuous systematic acquisitions, facilitating routine operations. The payload data downlink is required once per orbit, and the mission is such that this can be achieved with a single ground station with no blind orbits. The data is processed, calibrated and the resulting products routinely distributed for assembly and assimilation into operational ocean models.
Number 164 - Session 4
IMPROVED JASON-2 ALTIMETRY PRODUCTS FOR COASTAL OCEAN (PISTACH PROJECT)
C. Dufau 1, F. Mercier 1, M. Ablain 1, G. Dibarboure 1, L. Carrere 1, S. Labroue 1, E. Obligis 1, P. Sicard 1, P. Thibaut 1, J. Bouffard 2, A. Lombard 3, N. Picot 3
1 Collecte Localisation Satellites, Ramonville-Saint-Agne, France
2 Laboratoire d'Etudes Géophysique et Océanographie Spatiale, Toulouse, France
3 Centre National d'Etudes Spatiales, Toulouse, France
Abstract
As part of Jason-2 project, CNES is conducting a dedicated study to improve altimeter products in coastal areas and inland waters. This project called PISTACH for « Prototype Innovant de Système de Traitement pour les Applications Côtières et l'Hydrologie » is organized in 3 phases. The first one concerned a study of the user needs and of the structure of such products. The second phase deals with analysis, selection and development of new fields to be taken into account (retracking of the waveforms, radiometer and model wet troposphere correction, local model for correction of tides and atmospheric forcing, sea state bias, data editing). The third phase consists in prototype implementation, validation and operations during Jason-2 CalVal phases. Implemented during summer 2008, the PISTACH prototype will generate Level 2 (I)GDR altimeter products. The first products should be delivered in October.
The project, the prototype and the products will be presented at the meeting.
Number 98 - Session 5
INTEGRATION OF BIOGEOCHEMISTRY AND MARINE ECOSYSTEM MODEL IN MERCATOR-OCEAN SYSTEMS
A Elmoussaoui1, E Dombrowsky1, C Moulin2, L Bopp2, C Ethe2, E Greiner3, O Aumont4, P Monfray5
1 Mercator-Ocean, Toulouse, France
2 LSCE-CEA, Saclay, France
3 CLS, Toulouse, France
4 IRD, Plouzané, France
5 CNRS, Paris, France
Abstract
Accounting for ocean biogeochemistry and marine ecosystem dynamic is of strong interest in the context of Earth System modelling to better represent the marine component to the global atmospheric cycle of greenhouse gazes that influence climate as CO2. Furthermore, treating the ocean as a whole is also the way to address large anthropogenic impacts on marine systems as climate change, nutrients loading, acidification, and eventually overfishing and habitat destructuring. To forecast how interactions between marine biogeochemical cycles and ecosystems respond to and force global change, several efforts have been promoted on biogeochemical integration into operational Mercator Ocean systems.
The aim of this work is to implement a marine biogeochemical and ecosystem component at global scale into the MERCATOR operational system, using first PSY3 analysis at 1/4° then PSY4 at 1/12°. Previous works have conducted successfully the integration into the North-Atlantic domain of a multi-nutrient (LOBSTER, N2PZD type) and multi-nutrient and multi-plankton biogeochemical model (PISCES, N5P2Z2D2 type) into MERCATOR system at 1/3°. This allowed the use of MERCATOR operational analyses to drive near real time forecast of marine primary production. Near real time demonstrators have recently been tested, first, in early 2006 over the North Atlantic, second in 2008 at global scale. Results of both systems will be shown and advances on biogeochemical model integration within Mercator Systems will be discussed.
(Last Updated: 30-10-2008)