Monitoring and forecasting the Global Ocean

Author:

Yann Drillet - (MERCATOR OCEAN)

Co-Investigator(s):

Elisabeth Remy (MERCATOR OCEAN)
Jean Michel lellouche (MERCATOR OCEAN)
Mounir Benkiran (MERCATOR OCEAN)
Charles Emmanuel Testut (MERCATOR OCEAN)
Marie Drévillon (MERCATOR OCEAN)
Angélique Melet (MERCATOR OCEAN)
Pierre Yves Le Traon (MERCATOR OCEAN/Ifremer)
Claire Dufau (CLS)

Abstract:

Monitoring and forecasting the Global Ocean — Sea level anomaly (color) and surface current streamlines from the global high resolution analysis and forecasting system.

Mercator Ocean is in charge of the Global Monitoring and Forecasting Centre (GLO MFC) for Copernicus Marine Environment Monitoring Service (CMEMS). In this context, the operational production is performed to deliver multi year time series covering at least the altimetry era (from 1992) and near real time products including hindcasts and forecasts of the global ocean. The current systems used to deliver these products are based on global ocean configurations assimilating available in situ and satellite observations. The global ocean reanalysis (GLORYS) system is based on a ¼° configuration with assimilation of along track altimetry observation (AVISO/CMEMS SL TAC), satellite sea surface temperature maps (REYNOLDS), in situ temperature and salinity profiles (CORA/CMEMS INS TAC) and satellite sea ice concentration (CERSAT). The near real time system is a higher resolution global configuration (1/12°) with assimilation of along track altimetry observation (AVISO/CMEMS SL TAC), satellite sea surface temperature maps (OSTIA/CMEMS OSI TAC), in situ temperature and salinity profiles (CORA/CORIOLIS/CMEMS INS TAC) and satellite sea ice concentration (CMEMS OSI TAC). This production is disseminated to any user thanks to the CMEMS Central Information System (http://marine.copernicus.eu/) and the operational production is already consolidated in CMEMS until 2021. The multi year time series assimilating all available altimetry missions will be extended every year to be as close as possible to the real time. The near real time production, which assimilate also all the available altimetry missions, is updated every day producing daily a 10-day forecast. The scientific evolution of the global analysis and forecasting system used to produce global reanalysis and near real time forecast will include:

the ocean model component mainly to increase the resolution of the model, to improve numerical schemes and to add physical processes (as for example the tide)
the data assimilation scheme which is currently based on a SEEK filter and that will evolve to an ensemble method
the assimilated observations taking into account new kind or new processing of observations when available. For the altimetry observations, the spatial and temporal filtering of the along track observations and the different correction applied to the observations (DAC, tide, inverse barometer …) have a large impact on the analysis.

New metrics are regularly developed to quantify improvement of the main oceanic fields in comparison with observations for the analysis and/or for the forecast. Dedicated metrics to quantify the realism of some oceanic processes or structures as meso scales phenomena are developed. They are based on classical bias, rms or correlation diagnostics but also on algorithm to detect fronts or eddies, lagrangian metrics, spectral analysis.