Evaluating the impacts of the tropical Pacific observing system on the ocean analysis fields in the global ocean data assimilation system for operational seasonal forecasts in JMA

Impacts of TAO/TRITON (TT) and Argo data in the tropical Pacific on the accuracy of temperature and salinity fields generated by a data-assimilation system for operational seasonal forecasts are examined through a series of observing system experiments. This study demonstrates positive impacts of both TT and Argo data, and that these observation types are complementary to each other. Data assimilation has relatively large impacts around the thermocline in the NINO3 region and the far western equatorial Pacific. A close relationship between the impacts of data assimilation and oceanic inherent uncertainty is suggested.