Marine data assimilation is a vital component in the production of Met Office ocean products. By assimilating observations we aim to bring ocean models closer to reality.
Data assimilation greatly improves the ability of ocean models to produce accurate forecasts and meaningful hindcasts. The marine data assimilation group is responsible for the maintenance and improvement of the data assimilation component of Met Office ocean models.
Additionally, the marine data assimilation group is responsible for the upkeep and development of both the OSTIA system and the GMPE. OSTIA is a SST analysis product that is used for a wide range of applications, including numerical weather prediction and climate monitoring. GMPE is a SST product derived from many international SST analyses, including OSTIA.
Temperature and salinity profiles, SST, SSH, and sea ice concentration observations are all regularly assimilated into Met Office FOAM systems. Other ocean products assimilate a subset of these data types with, for instance, assimilation in OSTIA only using SST and sea ice. Much of the data comes from satellites with Jason and Envisat programmes providing SSH measurements, SST observations coming from GHRSST and the EUMETSAT OSI SAF providing sea ice concentration data. A wide variety of surface and profile in-situ measurements, including from the Argo programme, are also used. All data are quality controlled and bias corrected before assimilation.
At present assimilation within FOAM systems in the deep ocean and OSTIA uses an optimal interpolation type method which is currently being adapted for use with NEMO model configurations for the shelf seas. Work is in progress to update our systems to use the NEMOVAR variational assimilation scheme.