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List of poster abstracts
[A-B] [C-E] [F-G] [H] [I-K] [L] [M-O] [P-R] [S] [T-W] [X-Z]
Authors A-B
Abstract ID S4.1-63
MEAN SEA SURFACE HEIGHT IN THE WORLD OCEAN USING ARGO FLOAT AND ALTIMETRY
H. Abe and K. Hanawa
Graduate School of Science, Tohoku University, Sendai, Japan
Abstract
Since satellite altimetry provides only anomalies of sea surface height (SSH) from mean SSH field temporally averaged for 1992-1999, it is needed to estimate mean SSH field to obtain absolute SSH field from some reference surface, such as 2000db. In the present study, we newly developed procedure to obtain mean SSH field using the Argo float data and satellite altimetry data. By subtracting satellite SSH anomalies from the SSH estimated using temperature and salinity profile, we can obtain mean SSH. However, we cannot expect the exact coincidence in place and time between satellite altimetry and Argo float observation. Therefore we first estimate the statistics of temporal and spatial behavior of SSH variation using satellite altimetry and determine the match-up condition between satellite altimetry and Argo observation. The match-up conditions are different in latitude and longitude. It was found that, although the obtained mean SSH field is similar to that obtained using climatological temperature and salinity profiles such as WOA05 as a gross, there are significant differences especially in the regions of the western boundary currents and the Antarctic Circumpolar Current.
Fig. 1. Estimated MSSH at altimetric points.
Abstract ID S4.2-83
THE IMPORTANCE OF VALIDATION OF OCEAN MODELS IN A TRIPLY NESTED DOWNSCALING SYSTEM
J. Albretsen
Norwegian Meteorological Institute, Oslo, Norway
Abstract
The continued process to improve regional ocean models and assimilation methods is at the core of research at the Norwegian Meteorological Institute. To exclude the effects of data assimilation, long, well validated hindcast runs are important to be able to recognize the behaviour of the ocean model in our regional domains. The ocean forecast system at met.no has consisted of our own version of the well known Princeton Ocean Model (MI-POM) for the last two decades. The model has been tested and tuned to behave satisfactory in Norwegian waters, but we have also discovered its weaknesses and limitations. More modern ocean models with more advanced numerics are available from different communities. Based on results from long, validated model runs, met.no has decided to exchange MI-POM with ROMS (Regional Ocean Modeling System) which is developed by the Rutgers University and UCLA. Several data assimilation schemes have been implemented in the MI-POM model, and several schemes are available in the ROMS code. However, we also find it important to run our model without data assimilation to be able to recognize its behaviour and as a basic quality control.
A triply nested downscaling has been performed with both the MI-POM and the ROMS model for a period of the last 27 years (1981-2007) for an area covering the North Sea and Skagerrak. The global data applied comes from the SODA (Simple Ocean Data Assimilation) data base which is a re-analysis of the global ocean climate from 1958-2005 delivered as monthly means on a 0.5ox0.5o grid. The SODA data has then been nested into the two models, run first with a horizontal resolution of 4 km and then 1.5 km. The former resolution is eddy-permitting and the latter is eddy-resolving in the North Sea area. Model results from both models on both resolutions will be shown, and focus will be on validation of hydrography and currents and on energy diagnostics.
Abstract ID S4.3-10
A. AlveraAzcárate1, A. Barth1, R.H. Weisberg2
1AGO-GHER, University of Liège, Liège, Belgium
2College of Marine Sciences, University of South Florida, Saint Petersburg, USA
Abstract
A high-resolution (1/60 degree), three-dimensional numerical circulation model of the Cariaco basin (Venezuela) is constructed by nesting the Regional Ocean Modeling System (ROMS) in the 1/12 degree global Hybrid Coordinate Ocean Model (HYCOM). The Cariaco basin is a semi-enclosed trench located along the coast of Venezuela. Its maximum depth is about 1400 m, and it is connected to the open ocean by two shallow passages: the Centinela channel in the northwest (146 m depth) and the Tortuga channel in the northeast (135 m depth). The main objective of this work is to improve our knowledge of the Cariaco basin dynamics, and to understand how the basin is influenced by the Caribbean Sea. The nesting of the Cariaco model in HYCOM is therefore crucial for these analyses. First, the annual cycle of the basin is described, using the results from a 2004 hindcast. Then, two modes of interaction between the basin and the open ocean are studied: (i) the meanders and eddies that travel westward with the Caribbean Current, and (ii) a subsurface eastward current that flows along the South America north coast. The ventilation of the basin through its channels is analyzed by studying the annual variations of the thermocline depth in the basin channels. In addition to the improved knowledge of the Cariaco basin circulation, which can help to better understand the climate of the past through paleoceanographic studies, this work is also an example of the feasibility of one of the objectives of GODAE: downscaling from a large-scale model to a regional model. In particular, the nesting ratio of 5 used in this work (from 9 km down to 1.82 km) demonstrates that a high-resolution model can be successfully nested in HYCOM.
Abstract ID S4.4-11
USING MONOVARIATE AND MULTIVARIATE EOFs TO RECONSTRUCT
MISSING DATA WITH DINEOF
A. AlveraAzcárate1,A. Barth1, D. Sirjacobs1, J.M.Beckers1
1AGO-GHER, University of Liège, Liège, Belgium
Abstract
DINEOF (Data Interpolating Empirical Orthogonal Functions) is an EOF-based method to reconstruct missing data in geophysical data sets. DINEOF can be used to reconstruct monovariate data sets (as sea surface temperature (SST), chlorophyll, etc), and multivariate data sets with little increase in complexity. For multivariate reconstructions, extended EOFs are used, which take into account the interrelationships between related variables to infer data at missing locations. Spatial maps of the standard deviation of the reconstruction error can be also calculated.
In the past, DINEOF has been compared to Optimal Interpolation (OI) techniques for the Adriatic Sea SST. The results showed that DINEOF was faster than OI, making it very suitable for operational applications.
DINEOF was also more accurate when compared to in situ data. Another advantage of DINEOF is that there is no need for a priori knowledge of the statistics of the reconstructed data set (such as covariance or correlation length), thus reducing the subjectivity of the analysis.
DINEOF has been successfully used to reconstruct a large variety of domains over the world ocean, mostly at the regional scale. In addition to an overview of the technique's capabilities, limitations and future developments, recent work aimed to improve the quality of the reconstructions at the global and local scales will be presented.
Abstract ID S2.1-174
SURFACE TEMPERATURE-SALINITY RELATIONSHIP IN THE CONTEXT OF THE SMOS SATELLITE MISSION
A. Aretxabaleta1, J. Gourrion1, J. Ballabrera-Poy1, B. Mourre1, J. Font1
1Institut de Ciències del Mar -CSIC, SMOS Barcelona
Expert Centre on Radiometric Calibration and Ocean Salinity, Barcelona, Spain
Abstract
The relationship between surface temperature (SST) and surface salinity (SSS) is characterized in order to be used for the development and validation of satellite SSS products from the SMOS (Soil Moisture and Ocean Salinity) mission. The mission is scheduled for launch in spring 2009 with the objective of providing global SSS distributions. Estimates of the SST/SSS relationship are obtained from simple correlations of observed temperature and salinity from ARGO profiler data. This reveals areas of high correlation in the North Pacific (25N-45N) and North Atlantic (25N-50N). The density ratio (R), representing the relative effect of temperature and salinity on density, exhibits a similar latitudinal distribution. Analogous results are obtained from SSS and SST fields extracted from archived global 1/12 degree resolution HYCOM solutions (Nov03-Jun08). Analysis of the model fields using single-variate (SSS) and multi-variate (SSS, SST) statistics is conducted. The SSS analysis reveals a correspondence between the spatial modes extracted with Principal Component Analysis and the areas of higher variability (areas of high precipitation associated with the ITCZ, high river discharge, strong currents).
SMOS SSS products near coastal areas are likely to be noisy due to land contamination. Preliminary results using Multivariate Empirical Orthogonal Functions (MEOF) Analysis to improve the quality of these SSS products are presented. The main modes of variability from the combined SST/SSS MEOF may allow the projection of consistently available SST information into areas where SSS noise is too high.
Abstract ID S4.5-179
Assessment of GHRSST Level 4 sea surface temperature products in the
Gulf of Mexico and Gulf Stream regions
Edward Armstrong1, Jorge Vazquez1, and Michael Davis1
1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California,
USA
Abstract
The global ocean data assimilation experiment (GODAE) High-Resolution SST (GHRSST) Project has produced several sea surface temperature (SST) products based on a wide variety of infrared and microwave sensors. These include Level 4 global products that are typically produced at a 6-27 km spatial resolution with a daily temporal frequency. The Level 4 products are based on a statistical blend or merging of the Level 2 input data (e.g., optimal interpolation) and result in globally gap free data. Before such data can be used in coastal ocean model initialization or assimilation, it is necessary to assess their accuracy and validation in the region of interest to determine under what conditions they can be used in confidence. In this investigation, we analyze four GHRSST Level 4 products over a period of one year (June 2007-June 2008) in the Gulf of Mexico and Gulf Stream coastal regions. The in situ sources of SST for the assessments were 25 buoys from the NOAA National Data Buoy Center. These buoys were used for daily comparisons with the SST satellite sources that allowed us to spatially discriminate from very near shore to offshore locations where the dynamic oceanographic conditions can substantially change. The hourly SST measurements from the buoys were also used to temporally separate the validation into both a 24 hour daily comparison as well as a night-time only comparison to assess the confidence of a "foundation temperature" in the Level 4 SST products. Initial comparisons indicate the GHRSST products perform very well with root mean square differences less than 0.5°C for most locations and time periods.
Abstract ID S4.6-112
INFLUENCE FUNCTIONS OF SEA LEVEL AND SEA SURFACE TEMPERATURE MEASUREMENTS IN AN EDDY-PERMITTING MODEL OF THE NORTH ATLANTIC
N.K. Ayoub1, M. Lucas2
1LEGOS/CNRS, Toulouse, France
2CLS, Ramonville, France
Abstract
The characterization of model errors is an essential issue in data assimilation as the specification of forecast or background error covariances is required and greatly influences the quality of the assimilation results. Ocean General Circulation Model (OGCM) errors are usually unknown (or incompletely known), because of the complexity of the dynamics and because sources of model errors (e.g. errors on initial or boundary conditions) are themselves difficult to quantify. Ensemble Kalman Filter methods (Evensen, 2003) rely on a statistical estimate of error covariances from ensembles of simulations. From an ensemble generated by perturbing some parameters or initial/boundary conditions, one can compute influence functions (or 'representers' as discussed by Bennett, 1992 ) that is the influence of the perturbation of one variable onto other model variables at different space-time locations.
In this study, our objective is to estimate the influence functions of sea level (SL) measurements as provided by satellite altimetry and of sea surface temperature (SST) on other surface and subsurface variables (mainly temperature). We compare the space-time structure of the influence functions of SL and SST at the same location in order to better understand the potential impact of SST and SL data when used to constrain the model. Our approach is based on stochastic modelling. We are interested in the Gulf Stream area as simulated by the NEMO/OPA model in a ¼° horizontal resolution configuration of the North Atlantic (the 'NATL4' configuration from the DRAKKAR project). Atmospheric forcing fields come from the ERA40 reanalysis. We focus on a period of mixed-layer deepening (September 1994 ? March 1995). The ensemble of simulations is generated by perturbing the atmospheric forcing fields as described by Lucas et al. (2008) .
Abstract ID S5.1-116
IMPACT OF PHYSICAL AND BIOLOGICAL DATA ASSIMILATION ON THE GLOBAL SURFACE AIR-SEA FLUXES OF CO2
R. Barciela1, M. Martin2, J. Hemmings3
1Met Office, Exeter, UK
2Met Office, Exeter, UK
3National Oceanography Centre, Southmapton, UK
Abstract
The primary aim of the Centre for Observation of Air-sea Interactions and Fluxes (CASIX) is to estimate accurately the air-sea fluxes of CO2. Under CASIX, a high resolution, operational ocean general circulation model (FOAM), coupled to an ocean biogeochemistry model (HadOCC), has been used to provide global estimates of surface ocean pCO2 and air-sea fluxes of CO2. A material balancing scheme for ocean colour assimilation has been developed for the coupled model, with the aim of improving model estimates of air-sea CO2 fluxes. The scheme uses surface chlorophyll increments to determine increments for the biogeochemical tracers: nutrient, phytoplankton, zooplankton, detritus, DIC and alkalinity.
Multiyear global simulations, with and without biological assimilation, were run at 1 degree horizontal resolution, providing boundary conditions for a
limited area North Atlantic model at 1/3 degree resolution. Observed temperature and salinity data were also assimilated into the model. Inter-annual variability in the pCO2 fields are compared to observations, and primary production and pCO2 results of the two different resolution runs are compared. The impact of the biological data assimilation on all model variables is also assessed.
Abstract ID S4.7-102
An ERA40-based atmospheric forcing for simulations and reanalyses of the global ocean circulation between 1958 to present
Laurent Brodeau1, Bernard Barnier1, Anne-Marie Treguier2, Thierry Penduff1 and Sergei Gulev3
1LEGI, UMR 5519 CNRS-UJF, BP 53, 38041 Grenoble, France
2LPO, UMR 6523 CNRS-IFREMER-IRD-UBO, IFREMER, BP 70, 29280 Plouzané, France
3P.P. SIO - RAS, 36 Nakhimovsky ave, 117218 Moscow, Russian Federation
Abstract
This paper presents a new forcing data set for OGCMs that could be used for simulations or reanalyses for the period 1958-2004. ERA40 surface atmospheric fields and ECMWF operational analysis are combined with satellite-extracted radiative products into a forcing dataset intended to drive inter-annual hindcasts from 1958 to 2004 with a global ocean general circulation model (OGCM). The approach used to evaluate ERA40 surface fields stands on realistic inter-annual simulations of a coarse-resolution OGCM, rather than on heat and freshwater fluxes budget closures, which are only verified a-posteriori. ERA40 surface atmospheric state variables are used only to calculate the turbulent fluxes, and we rely on satellite products for radiation and precipitation. Corrections are proposed to improve time discontinuities and biases on each input atmospheric field. Inter-tropical surface air humidity of ERA40 is increased prior to the satellite era (1979) and decreased after. Arctic temperatures are decreased, and wind speeds are globally increased relying on 6 years of QuikSCAT scatterometer wind estimates. Correction of the downwelling shortwave radiation component of the ISCCP-FD product is also performed to improve sea surface temperature representation with ther model. 47 year long experiments with the low-resolution global ocean-ice model are carried out to evaluate the impact of the every correction on the model solution.
Abstract ID S4.8-23
A WEST FLORIDA SHELF ROMS MODEL NESTED IN HYCOM:
VALIDATION, APPLICATION AND DATA ASSIMILATION
A. Barth1, A. AlveraAzcarate1,
L. Zheng2, and R.H. Weisberg2
1 University of Liege, AGO/GHER, Institut de Physique B5, Liege, 4000, Belgium
2 University of South Florida, 140 Seventh Avenue South, St. Petersburg, FL 33701, United States
Abstract
A high-resolution regional model for the West Florida Shelf based on ROMS is nested into the GODAE Atlantic and Global HYCOM models. The benefit of using HYCOM boundary conditions instead of climatology is established by comparing the nested model to altimetry, in situ temperature time series, andADCP and high-frequency (HF) radar currents.
Jointly with the Fish and Wildlife Research Institute, the model is applied to assist in harmful algae bloom forecasts. The model currents are used to estimate the trajectories of water parcels where red tide organisms have been detected. This system has been able to simulate the onset of the 2005 red tide event.
HF Radar Currents are assimilated to improve the shelf circulation. An ensemble simulation of the WFS ROMS model is carried out under different wind forcings in order to estimate the error covariance of the model state vector and the covariance between ocean currents and winds. Radial currents measured by HF Radar antennas near St. Petersburg and Venice, FL, are assimilated using this ensemble-based error covariance. Different assimilation techniques using a time-average ensemble, a filter to reduce surface gravity waves and an extended state vector including wind stress were tested. Results of WFS ROMS model assimilating surface currents show an improvement of the model currents not only at the surface but also at depth.
This model is run daily, to provide forecasts for the next 3.5 days. The model predictions and validations are available at http://ocgweb.marine.usf.edu under "WFS Model Forecasts".
Abstract ID S3.1-81
Impact study of the number Space Altimetry observing systems on the altimeter data assimilation in the Mercator-Ocean system
Mounir Benkiran1, Eric Greiner1, Sylvie Giraud St Albin1, Eric Dombrowsky2, Didier Jourdan3 and Mathilde Faillot3
1CLS Space Oceanography Division 8-10 Rue Hermes 31526 Ramonville St Agne Cedex
2MERCATOR Ocean 8-10 Rue Hermes 31526 Ramonville St Agne Cedex
3SHOM/HOM 42 Avenue G. Coriolis 31057 Toulose Cedex
Abstract
The impact of the number of space altimeter satellites and the data number SLA observations available for assimilations is assessed using one eddy resolving experimental data assimilation system PSY2V2. And twin experiments performed in delayed-time conditions (2004-2005) when 4 datasets are available. The assimilation system is based on the Reduced-Order Optimal Interpolation algorithm and uses 1D vertical multivariate EOFs to extract statistically-coherent information from the observations. In first step, we analyse here their respective impact on the analysis. We led several simulations in parallel that we compare with a simulation that we shall call after reference simulation Sref. In the reference simulation Sref, we assimilate the altimeter data (Jason, Envisat and Gfo). For all the simulations presented, we leave the same restart. We made these simulations over six months. First of all, we shall show that it is important to use the altimetry data stemming from various satellites, in particular when their spatial resolutions are different (Jason1, Envisat, Gfo and Topex). In a second step, we compare the performance of fast delivery products with respect to delayed time data. The validation with independent in-situ data (tide gauge and drifter data) demonstrates a clear degradation of real time in relation to delayed time. To obtain the same quality we need: 1 altimeter for hindcast, 2 altimeters for nowcast and 4 altimeters for forecast. This is essentially due to the fact that to compute the real time only observations of the past are accessible.
Abstract ID S3.2-95
Surface velocity observations and Experiments to assess their usefulness in Operational Ocean Data Assimilation Forecasting Systems
Eric Greiner1, Mounir Benkiran1, Sylvie Giraud St Albin1 and Mathilde Faillot2
1CLS, Ramonville Ste Agne, France
2 SHOM/CMO, 13 rue du Chatellier, 29603 BREST CEDEX, France
Abstract
Surface velocity is nowadays the most strategic ocean state variable for scientific, commercial and especially military operational oceanography applications. Recent advances in satellite observation of surface currents have motivated this prospective study founded by SHOM with support from GIP Mercator Océan to assess the potential of space-borne sensors to complement actual satellite altimetry Observing System in the framework of data assimilation in ocean circulation models.
The main motivation for this study is to assess the capabilities of these new surface currents products to maintain and improve the quality of the forecasts of actual Operational Ocean Forecasting Systems such as PSY1, the 1/3° North-Atlantic System from GIP Mercator Océan. The objective is to assess the usefulness relatively to the "conventional" assimilation datasets and particularly to the satellite altimetry along-track sea level anomaly products from SSALTO/DUACS.
The field experiment stands on performing Observing System Simulation Experiments (OSSEs) following Atlas (1997) that share a "simulated" observational assimilation dataset. OSSE provide an appropriate framework to quantify the relative impact of the different datasets used in the "fraternal twin" assimilation simulations.
Two types of experimental mapped sea-surface velocity products are tested : direct radial components of the sea surface velocity products derived from the Doppler Anomaly from ENVISAT's ASAR data following Chapron et al. (2005) that are restricted to coastal areas (400 km offshore), and indirect horizontal sea surface velocities products derived from the Optical Flow method [Vigan et al., 2000] applied to thermal space imagery of the sea surface ocean (sea surface temperature and ocean color images) that have a cloud-sensitive global coverage. Both have "realistic" instrumental errors of 30 cm/s.
The second panel of this study is to step forward to Observing System Experiments (OSE) using real data from existing missions that are specifically provided by BOOST Technologies company in near-real time conditions. Results from a short experiment in real-time are presented. Results are validated against lagrangian drifter trajectories and the impact of the complementary information provided by this new dataset is assessed by direct comparison and rely on theoretical concepts.
Abstract ID S3.3-47
ICE AND OCEAN FORECASTING WITH THE TOPAZ SYSTEM
Laurent Bertino 1, Knut A. Lisæter1, Annette Samuelsen1, François Counillon1, Cecilie Hansen1, Intissar Keghouche1, Goran Zangana1...
1Mohn-Sverdrup Center / NERSC, Bergen, Norway
Abstract
The TOPAZ monitoring and forecasting system covers the North Atlantic and Arctic Oceans. It has been providing weekly forecasts out to 10 days ahead since January 2003. TOPAZ is based on the Hybrid Coordinate Ocean Model (HYCOM, http://www.hycom.org ) with a horizontal resolution varying from 11km in the Arctic to 16 km in the North Atlantic and 22 hybrid vertical layers. It uses 6-hourly forcing fields from the ECMWF and assimilates:
- Altimeter data (merged maps from CLS)
- NOAA Sea Surface Temperatures
- Sea-ice concentrations from NSIDC
- Lagrangian sea-ice drift products from CERSAT/Ifremer
- Argo temperature and salinity profiles from the Coriolis center
All data are assimilated with the Ensemble Kalman Filter (EnKF, http://enkf.nersc.no ). The physical model is also coupled online to an ecosystem model, the Norwegian Ecosystem Model (NORWECOM) developed at the IMR.
The system is nested to high-resolution models of the North Sea, Barents Sea, Gulf of Mexico for specific developments such as ecosystem modeling, iceberg modeling and ensemble ocean forecasting. TOPAZ provides standard interpolated products on the OPeNDAP (see http://topaz.nersc.no). TOPAZ is a contributor to the Arctic ROOS and represents the Arctic marine forecasting center of the European MyOcean project. TOPAZ is now exploited in met.no's operational suite since early 2008. The poster shows an overview of the system and its applications and recent validation results obtained within the MERSEA targeted validation period.
Abstract ID S5.2-178
OCEAN FORECASTING FOR ACOUSTICAL APPLICATIONS
John Blaha, Jay Wallmark, Frank Bub
Naval Oceanographic Office, Stennis Space Center, Mississippi, USA
Abstract
This paper outlines efforts at the Naval Oceanographic Office to attain numerical model simulations of ocean temperature (sound speed) optimized for Navy acoustical sensors. The prominent feature of this activity is the need to integrate the sensitivity of selected acoustical sensors with simulations of ocean variability and with the Navy's capacity to improve those simulations through ocean observations. Experience continues to show that Navy shipboard acoustical systems are sensitive to a spectrum of ocean variability and dynamical scales. Against this sensitivity to real and modelled variability of ocean temperature is the pressing requirement to quantify uncertainty in the modelled fields in the vicinity of sensor deployment. The match-up between determinations of sensitivity and forecast uncertainty drives deployment of Navy sampling assets, as gliders, profiling floats, ships and aircraft, on a continual basis. Progress at the Naval Oceanographic Office toward estimating sensitivity and model uncertainty has depended on experimentation and on development of analysis practices embedded within the forecast production. The approach in practice today is to engage numbers of individuals in the daily interpretation of modeled fields and ocean observations. Different ocean settings have yielded different assessments of model performance, largely depending on the dynamical scales and complexity of the phenomena driving temperature variance. Experiences taken from Fleet exercises reinforce the importance of high-resolution circulation modeling both to integrate the effects of differing scales of variability and to render interactions among scales. The need to develop a stronger observational basis, more configurable and able to support and verify particular ocean processes in forecast models, is also apparent.
Abstract ID S4.9-121
4D-VARIATIONAL DATA ASSIMILATION FOR LOCALLY NESTED
NUMERICAL OCEAN MODELS
E. Simon1,2, L. Debreu1, E. Blayo1
1University of Grenoble and INRIA, Grenoble, France
2NERSC, Bergen, Norway
Abstract
A common way to develop regional ocean modeling systems consists in embedding a high resolution local model into a coarse resolution model covering a larger domain. The local model then takes its boundary conditions from its parent model (one-way interaction), while the parent model solution may additionally be periodically updated using the local fine resolution solution (two-way interaction).
However, for data assimilation purposes, the multigrid structure of the modeling system is generally ignored. One assimilates data either in one of the two models only, or in both models separately, but without properly taking into account the interactions between the two numerical solutions.
In this poster, we address the problem of 4D-variational data assimilation in such locally nested models, for the control of the initial conditions on both models. The adjoint system is derived in both cases of one-way and two-way interactions. It is shown that the adjoint formulation adds new interactions between the grids, in the opposite sense of the interactions existing in the direct formulation. In particular, in the one-way case, the adjoint formulation creates a retroaction term from the fine grid onto the coarse grid. The design of the
multigrid background error covariance matrix is also discussed, as well as the addition of a new control variable corresponding to the errors in the interactions between the coarse resolution and fine resolution solutions.
These formulations are illustrated and discussed in the idealized test case of a 2D shallow water model. In particular, it is shown that this multigrid approach leads to improved results with regard to the usual method consisting in the assimilation of data on the local fine resolution model only, with a control of its corresponding initial condition and of its boundary values.
Abstract ID S2.2-86
REGIONAL FOAM CONFIGURATIONS
E. Blockley, R. Barciela, A. Hines, D. Lea, R. Mahdon, M. Martin, M. McCulloch, J. Stark, D.
Storkey
Met Office, Exeter, UK
Abstract
The operational Forecasting Ocean Assimilation Model (FOAM) system has recently undergone large-scale modifications. The model component has been changed to use the NEMO model and the resolution of the system has been increased to a ¼ degree global model (from 1 degree).
Within the global FOAM-NEMO 1/4 degree system are three nested, higher resolution, regional models for the North Atlantic Basin, the Indian Ocean and the Mediterranean Sea. These regional configurations use the same NEMO model, on a more detailed 1/12th degree resolution grid, and implement the same assimilation scheme and 6 hourly fluxes as the global FOAM.
A description of the various regional FOAM configurations will be given along with results from recent hindcast runs. Model validation in the form of comparisons with the previous FOAM system as well as in situ and satellite observations will also be presented.
Abstract ID S2.3-183
EUMETSAT'S OPERATIONAL SATELLITE
OCEANOGRAPHY SERVICES
Hans Bonekamp1, Francois Parisot1
1European Organisation for the Exploitation of Meteorological Satellites, Darmstadt, Germany
Abstract
The European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) is one of Europe's leading centers in Earth Observation. EUMETSAT provides the key infrastructure to guarantee a timely provision of high-quality observational data originating from operational satellite systems and it's involvement in operational satellite oceanography is growing. Ex general. EUMETSAT is one of the operational centers within the Jason-2 program, delivering altimeter products in near real time over the global ocean. Secondly, being part of EUMETSAT's distributed ground system network, the Ocean and Sea Ice Satellite Application Facility (OSI-SAF) is disseminating state-of-the-art- products of e.g. sea surface temperature, surface heat fluxes, sea surface winds and sea ice. Moreover, EUMETSAT is collaborating with several other agencies to set-up near real time services from third party missions. In this presentation, the EUMETSAT contribution to the Jason-2 program will be presented, highlighting the global direct broadcast dissemination capabilities (GEONETCAST). In addition, the presentation will provide an overview of the status of the various oceanographical products and will outline the satellite oceanography activities planned for the near and long term future.
Abstract ID S3.4-137
ASSIMILATION SYSTEMS AND SATELLITE-DERIVED METHODS
Fabrice Bonjean1, Gary S.E. Lagerloef1, Kathleen Dohan1
1Earth & Space Research, Seattle, USA
Abstract
The upper ocean dynamics and the surface ocean motions have crucial impacts on many oceanic and environmental processes including climate variations and material transport, as well as on societal activities such as navigation. Monitoring the surface circulation has been a major scientific 
goal of the surface topography science team since the beginning of the satellite altimetry missions. These missions and others such as the space-based sea surface wind and sea surface temperature measurements have allowed different surface current monitoring methods to evolve and be used in research and operational contexts.
Two complementary methods are evaluated here: first, the general data assimilation systems (DAS) are GCM-based systems utilized for comprehensive ocean state description and forecast whose implementation is one of the main goals of GODAE; second, the direct calculation of surface currents from satellite observation, such as the NOAA-Ocean Surface Current Analyses Real-time (OSCAR, http://www.oscar.noaa.gov, see figure). The OSCAR surface current product has been routinely compared with in-situ data such as global surface drifter data and equatorial mooring measurements, and the validation results have been available at the OSCAR website. The main objective of this study is to assess the accuracy of the DAS procedures in describing the open ocean surface circulation by extending this type of comparison to various DAS products. This is carried out by intercomparing the surface current products in hindcast or delayed-time modes with the remaining independent in-situ data. This comparison methodology defines a metric intrinsic to the surface current field that can be systematically used to evaluate the quality of a DAS product and its strengths or weaknesses with respect to direct satellite-derived methods. The intercomparison results will be available on-line and routinely updated at the OSCAR website.
Abstract ID S2.4-77
BLUElink> Ocean Model, Analysis and Prediction System (OceanMAPS)
G. B. Brassington1, G. Warren2, T. Pugh1, X. Huang2, P. R. Oke3 and A. Schiller3
1CAWCR/Bureau of Meteorology, Melbourne, Australia
2Bureau of Meteorology, Melbourne, Australia
3CAWCR/CSIRO and Weath from Oceans Flagship, Hobart, Australia
Abstract
On the 2nd August 2007 the BLUElink Ocean Model, Analysis and Prediction System (OceanMAPS) was officially launched and announced through the local media as a major new public service. BLUElink was a successful three partner collaborative project between the Bureau of Meteorology, CSIRO and the Royal Australian Navy. BLUElink set upon a challenging plan to develop a completely new operational mesoscale ocean prediction system based on a model with climate heritage and to transfer this system to operations within 4 years. The speed of progress and the quality of products benefited greatly from both the Global Ocean Observing System and the Global Ocean Data Assimilation Experiment. The open data sharing policy, the establishment of data servers and the active scientific exchange have all contributed to the success of this system for which we gratefully acknowledge. The continuity of satellite coverage and the operationalisation of key components of the observational, data processing and communications systems are critical activities and challenges for establishing BLUElink OceanMAPS, and like systems, as a quality service. The present system routinely delivers ocean forecast information in the form of data products and online graphics as a public service to the Australian community. Applications have included; non tidal coastal sea level for flood warnings and port management; coastal upwelling for public health warnings, coastal fog warnings and marine productivity; boundary current forecasts for ship routing, ship salvage and towing, offshore platform operations and marine weather; heat content for tropical cyclone forecasting, marine park management for coral bleaching and climate impacts to coastal precipitation; ocean stratification for sonar applications for defense operations and hydrographic surveys; and numerous eco-tourism, recreational and research applications. The continuous improvement of the BLUElink system through: basic and applied research; operationalisation of the observing system and infrastructure; further enhancement of the observing system through new technologies and optimized deployment strategies; international forecast intercomparison exercises as well as future advances in consensus forecasting, ensemble forecasting and coupled modeling will significantly enhance and extend the predictive capabilities for the Australian community into the future.
Abstract ID S4.10-150
Investigation on an oceanic index for monitoring Tropical Cyclones
Claude Vanroyen1, Caroline Agier2 and Silvana Buarque3
1Météo-France Nouvelle Calédonie, 5 rue Vincent Auriol Faubourg Blanchot BP151 98845 Nouméa;
2Météo-France, 42 avenue Gaspard Coriolis, 31057 Toulouse Cedex, France
3Mercator Ocean, 8-10 rue Hermes, Parc Technologique du Canal, 31520 Ramonville Sainte Agne, France
Abstract
Since January 2007, Mercator-Ocean investigates the ability of their Operational Forecast Systems (OFS) to monitor the Tropical Cyclones (TC) by examining modifications of the Sea Surface Temperature (SST), Sea Level Anomaly (SLA), Tropical Cyclone Heat Potential (TCHP) and the depth of isotherm 26°C (D26) in relation with the pressure estimated at the centre of the TC. These parameters, coming from satellite observations, are daily diffused by the Atlantic Oceanographic and Meteorological Laboratory (AOML) and are used by forecasters as additional data to evaluate the variation of the TC intensity. Indeed, these parameters carry mainly thelow-frequency of the ocean and thanks to these observations the information concerning the "past time" (observations and analysis) can already be a useful oceanic index to give the tendency of the TC intensification. However, what's about the high-frequency changes of oceanic parameters and their consequences over the TC intensification?
This work examines the Mercator Ocean OFS by analysing the parameters integrating both the low-frequency and the high frequency variability. The ability of these parameters to predict the TC intensity is showed through their correlation with the estimated central pressure. The distribution of the energy available in oceanic upper layers to be extracted by heat exchanges processes towards the atmosphere is highlighted through the exploitation of the Interacting Tropical Cyclone Heat Content (ITCHC). By this way, an ocean atmosphere index taking into account the high-frequency behaviour of oceanic upper layers is proposed and validated for 26 TC observed between January 2007 and June 2008.
Keywords: Oceanography, Oceanic Index, Forecast, Tropical Cyclones, Heat Flux
(Last Updated: 30-10-2008)