Recent development of the Met Office operational ocean forecasting system: an overview and assessment of the new Global FOAM forecasts

Abstract

Abstract. The Forecast Ocean Assimilation Model (FOAM) is an operational ocean analysis and forecast system run daily at the Met Office. FOAM provides modelling capability in both deep ocean and coastal shelf sea regimes using the NEMO (Nucleus for European Modelling of the Ocean) ocean model as its dynamical core. The FOAM Deep Ocean suite produces analyses and 7-day forecasts of ocean tracers, currents and sea ice for the global ocean at 1/4° resolution. Satellite and in situ observations of temperature, salinity, sea level anomaly and sea ice concentration are assimilated by FOAM each day over a 48 h observation window. The FOAM Deep Ocean configurations have recently undergone a major upgrade which has involved the implementation of a new variational, first guess at appropriate time (FGAT) 3D-Var, assimilation scheme (NEMOVAR); coupling to a different, multi-thickness-category, sea ice model (CICE); the use of coordinated ocean-ice reference experiment (CORE) bulk formulae to specify the surface boundary condition; and an increased vertical resolution for the global model. In this paper the new FOAM Deep Ocean system is introduced and details of the recent changes are provided. Results are presented from 2-year reanalysis integrations of the Global FOAM configuration including an assessment of short-range ocean forecast accuracy. Comparisons are made with both the previous FOAM system and a non-assimilative FOAM system. Assessments reveal considerable improvements in the new system to the near-surface ocean and sea ice fields. However there is some degradation to sub-surface tracer fields and in equatorial regions which highlights specific areas upon which to focus future improvements.

A high-resolution ocean and sea-ice modelling system for the Arctic and North Atlantic oceans

“…It should be noted here that NEMO-LIM2 users can tune the total ice extent and volume by adjusting the parameter hiccrit (Wang et al, 2010), a characteristic thickness that is used to determine changes in open water area during ice growth. Nonetheless, overestimation of the total ice extent or volume is often reported in NEMO-related publications (Massonnet et al, 2011;Blockley et al, 2014), likely related to the use of a too-large value of the aforementioned parameter for given configuration and forcing. ORCA12-T321 used hiccrit = 0.6 m and the same value is applied in the CREG12 LIM2 runs.…”

Observing and modelling phytoplankton community structure in the North Sea

“…As part of the Forecasting Ocean Assimilation Model (FOAM; Blockley et al, 2014) suite of models, NEMO-ERSEM is run operationally at the Met Office on a daily basis, providing 5-day forecasts of physical and biogeochemical variables for the Northwest European Shelf seas. Analyses and forecasts are publicly available through the Copernicus Marine Environment Monitoring Service (CMEMS; http://marine.copernicus.eu), which is the operational service building on the MyOcean project.…”

A seamless approach to understanding and predicting Arctic sea ice in Met Office modelling systems

“…GloSea5 [39] is an upgrade to GloSea4 including an increase to N216-ORCA025 resolution, with initial sea ice and ocean conditions now being provided by the NEMOVAR assimilation scheme [51] as configured for the FOAM ocean forecasting system [52].…”