Coupling hydrodynamic and wave models: first step and sensitivity experiments in the Mediterranean Sea

This work describes the first step towards a fully coupled modelling system composed of an ocean circulation and a wind wave model. Sensitivity experiments are presented for the Mediterranean Sea where the hydrodynamic model NEMO is coupled with the third-generation wave model WaveWatchIII (WW3). Both models are implemented at 1/16° horizontal resolution and are forced by ECMWF 1/4° horizontal resolution atmospheric fields. The models are two-way coupled at hourly intervals exchanging the following fields: sea surface currents and temperature are transferred from NEMO to WW3 by modifying the mean momentum transfer of waves and the wind speed stability parameter, respectively. The neutral drag coefficient computed by WW3 is then passed to NEMO, which computes the surface stress. Five-year (2009–2013) numerical experiments were carried out in both uncoupled and coupled mode. In order to validate the modelling system, numerical results were compared with coastal and drifting buoys and remote sensing data. The results show that the coupling of currents with waves improves the representation of the wave spectrum. However, the wave-induced drag coefficient shows only minor improvements in NEMO circulation fields, such as temperature, salinity, and currents

The Copernicus Marine Service ocean forecasting system for the Mediterranean Sea

The Mediterranean Monitoring and Forecasting Center (MED-MFC) is part of the Copernicus Marine Environment and Monitoring Service (CMEMS) and provides regular and systematic information on the time-evolving Mediterranean Sea physical (including waves) and biogeochemical state. The systems consist of 3 components: 1) Med-Physics, a numerical ocean prediction systems, based on NEMO model, that operationally produces analyses, reanalysis and short term forecasts of the main physical parameters; 2) Med-Biogeochemistry, a biogeochemical analysis, reanalysis and forecasting system based on the Biogeochemical Flux Model (BFM) which provides information on chlorophyll, phosphate, nitrate, primary productivity, oxygen, phytoplankton biomass, pH and pCO2; 3) Med-Waves based on WAM model and providing analysis, forecast and reanalysis products for waves. The systems have been recently upgraded at a resolution of 1/24 degree in the horizontal and 141 vertical levels. The Med-Physics analysis and forecasting system is composed by the hydrodynamic model NEMO 2-way coupled with the third-generation wave model WaveWatchIII and forced by ECMWF atmospheric fields. The model solutions are corrected by the 3DVAR data assimilation system (3D variational scheme adapted to the oceanic assimilation problem) with a daily assimilation cycle of sea level anomaly and vertical profiles of temperature and salinity. The model has a non-linear explicit free surface and it is forced by surface pressure, interactive heat, momentum and water fluxes at the air-sea interface. The biogeochemical analysis and forecasts are produced by means of the MedBFM v2.1 modeling system (i.e. the physical-biogeochemical OGSTM-BFM model coupled with the 3DVARBIO assimilation scheme) forced by the outputs of the Med-Physics product. Seven days of analysis/hindcast and ten days of forecast are bi-weekly produced on Wednesday and on Saturday, with the assimilation of surface chlorophyll concentration from satellite observations. In-situ data are mainly used to estimate model uncertainty at different spatial scales. The Med-Waves modelling system is based on the WAM Cycle 4.5.4 wave model code. It consists of a wave model grid covering the Mediterranean Sea at a 1/24° horizontal resolution, nested to a North Atlantic grid at a 1/6° resolution. The system is forced by ECMWF winds at 1/8°. Refraction due to surface currents is accounted by the system which assimilates altimeter along-track significant wave height observations. On a daily basis, it provides 1-day analysis and 5-day forecast hourly wave parameters. Currently, wave buoy observations of significant wave height and mean wave period along with satellite observations are used to calibrate and validate the Med-waves modelling system.PublishedHalifax, Nova Scotia, Canada4A. Oceanografia e clim

Mediterranean monitoring and forecasting operational system for Copernicus Marine Service

The MEDiterranean Monitoring and Forecasting Center (Med-MFC) is part of the Copernicus Marine Environment Monitoring Service (CMEMS, http://marine.copernicus.eu/), provided on an operational mode by Mercator Ocean in agreement with the European Commission. Specifically, Med MFC system provides regular and systematic information about the physical state of the ocean and marine ecosystems for the Mediterranean Sea. The Med-MFC service started in May 2015 from the pre-operational system developed during the MyOcean projects, consolidating the understanding of regional Mediterranean Sea dynamics, from currents to biogeochemistry to waves, interfacing with local data collection networks and guaranteeing an efficient link with other Centers in Copernicus network. The Med-MFC products include analyses, 10 days forecasts and reanalysis, describing currents, temperature, salinity, sea level and pelagic biogeochemistry. Waves products will be available in MED-MFC version in 2017. The consortium, composed of INGV (Italy), HCMR (Greece) and OGS (Italy) and coordinated by the Euro-Mediterranean Centre on Climate Change (CMCC, Italy), performs advanced R&D activities and manages the service delivery. The Med-MFC infrastructure consists of 3 Production Units (PU), for Physics, Biogechemistry and Waves, a unique Dissemination Unit (DU) and Archiving Unit (AU) and Backup Units (BU) for all principal components, guaranteeing a resilient configuration of the service and providing and efficient and robust solution for the maintenance of the service and delivery. The Med-MFC includes also an evolution plan, both in terms of research and operational activities, oriented to increase the spatial resolution of products, to start wave products dissemination, to increase temporal extent of the reanalysis products and improving ocean physical modeling for delivering new products. The scientific activities carried out in 2015 concerned some improvements in the physical, biogeochemical and wave components of the system. Regarding the currents, new grid-point EOFs have been implemented in the Med-MFC assimilation system; the climatological CMAP precipitation was replaced by the ECMWF daily precipitation; reanalysis time-series have been increased by one year. Regarding the biogeochemistry, the main scientific achievement is related to the implementation of the carbon system in the Med-MFC biogeochemistry model system already available. The new model is able to reproduce the principal spatial patterns of the carbonate system variables in the Mediterranean Sea. Further, a key result consists of the calibration of the new variables (DIC and alkalinity), which serves to the estimation of the accuracy of the new products to be released in the next version of the system (i.e. pH and pCO2 at surface). Regarding the waves, the system has been validated against in-situ and satellite observations. For example, a very good agreement between model output and in-situ observations has been obtained at offshore and/or well-exposed wave buoys in the Mediterranean Sea.PublishedVienna3SR. AMBIENTE - Servizi e ricerca per la Societ

The Copernicus Marine Environment Monitoring Service Ocean State Report

The Copernicus Marine Environment Monitoring Service (CMEMS) Ocean State Report (OSR) provides an annual report of the state of the global ocean and European regional seas for policy and decision-makers with the additional aim of increasing general public awareness about the status of, and changes in, the marine environment. The CMEMS OSR draws on expert analysis and provides a 3-D view (through reanalysis systems), a view from above (through remote-sensing data) and a direct view of the interior (through in situ measurements) of the global ocean and the European regional seas. The report is based on the unique CMEMS monitoring capabilities of the blue (hydrography, currents), white (sea ice) and green (e.g. Chlorophyll) marine environment. This first issue of the CMEMS OSR provides guidance on Essential Variables, large-scale changes and specific events related to the physical ocean state over the period 1993–2015. Principal findings of this first CMEMS OSR show a significant increase in global and regional sea levels, thermosteric expansion, ocean heat content, sea surface temperature and Antarctic sea ice extent and conversely a decrease in Arctic sea ice extent during the 1993–2015 period. During the year 2015 exceptionally strong large-scale changes were monitored such as, for example, a strong El Niño Southern Oscillation, a high frequency of extreme storms and sea level events in specific regions in addition to areas of high sea level and harmful algae blooms. At the same time, some areas in the Arctic Ocean experienced exceptionally low sea ice extent and temperatures below average were observed in the North Atlantic Ocean

Copernicus Ocean State Report, issue 6

The 6th issue of the Copernicus OSR incorporates a large range of topics for the blue, white and green ocean for all European regional seas, and the global ocean over 1993–2020 with a special focus on 2020

Operating of TALOS wave energy converter in different wave climates

TALOS wave energy converter is a point absorber proposed at Lancaster University (UK), with its main advantage being its ability to absorb energy from all motion modes (i.e. multi-axis Power-Take-Off system). Following previous computational studies in the frame of device development (including frequency-domain modelling), here we present a motion study response for the TALOS wave energy converter for selected wave climates. The analysis applies to realistic irregular wave conditions, assuming a semi-empirical spectrum representative of chosen wave climates, and hydrodynamic modelling is combined with Copernicus Marine Service wave reanalyses data. After scatter plots of significant wave height and energy period are prepared, future considerations are discussed for the device size adjustments under different wave climate

River runoff and Dardanelles Strait implementations in the Mediterranean Sea numerical modelling system

This contribution aims at presenting the numerical model developments recently implemented in an eddy-resolving Mediterranean Sea modelling system based on the Ocean General Circulation Model (OGCM) NEMO (Nucleus for European Modelling, [Madec et al., 2017]. In this implementation the model has a horizontal resolution of 1/24° and it is resolved over 141 z vertical levels [Clementi et al., 2017]. The developments are related to the implementation of an increased number of freshwater river outlets and to the improvement of the Dardanelles Strait representation in the numerical modelling system.PublishedRome4A. Oceanografia e clim