The Mid-Atlantic Current Hindcast

Abstract

Advanced numerical modelling technology enables detailed characterisation of ocean current conditions in regions of complex hydrodynamics, such as the deeper water provinces of the continental slope. Model simulation of longterm historical conditions can significantly enhance the understanding of ocean conditions in a given location, increase the value of relatively short-term in-situ measurements, and hence reduce the uncertainty in engineering design and operational planning. However, such model results must be shown to be fully 'fit for purpose', which has often been a challenge to the research community. The Mid-Atlantic Current Hindcast (MACH) is a cooperative initiative between the UK Met Office, Oceanweather Inc. and BMT ARGOSS, to undertake a high integrity numerical model reanalysis of layered ocean current, temperature and salinity over a twenty year period. Applications of the resultant dataset include support to deep water offshore engineering design, marine operational planning and oil spill simulation. The project utilises state of the art assimilative ocean modelling technology and very high quality wind forcing. With the engagement of oil and gas majors, the modelling system is tuned and independently extensively validated against comprehensive in-situ oceanographic measurements. The nested ocean model system includes a coarse grid of the central and South Atlantic Ocean, and a nested very fine resolution grid covering all of the principal oil and gas concession areas in West Africa. The modelling approach also facilitates nesting fine resolution grids along the eastern Atlantic coast of South America, which provides future possibilities for deep water Brazil. The paper presents details of the modelling system, its configuration and testing during an initial pilot integration.