Evaluation of an Ocean Reanalysis System in the Indian and Pacific Oceans

This paper describes an ocean reanalysis system in the Indian and Pacific oceans (IPORA) and evaluates its quality in detail. The assimilation schemes based on ensemble optimal interpolation are employed in the hybrid coordinate ocean model to conduct a long-time reanalysis experiment during the period of 1993-2020. Different metrics including comparisons with satellite sea surface temperature, altimetry data, observed currents, as well as other reanalyses such as ECCO and SODA are used to validate the performance of IPORA. Compared with the control experiment without assimilation, IPORA greatly reduces the errors of temperature, salinity, sea level anomaly, and current fields, and improves the interannual variability. In contrast to ECCO and SODA products, IPORA captures the strong signals of SLA variability and reproduces the linear trend of SLA very well. Meanwhile, IPORA also shows a good consistence with observed currents, as indicated by an improved correlation and a reduced error.

Automated summary

This paper describes an ocean reanalysis system (IPORA) in the Indian and Pacific oceans and evaluates its quality in detail. The system uses assimilation schemes based on ensemble optimal interpolation in a hybrid coordinate ocean model to conduct a long-term reanalysis experiment from 1993 to 2020. The performance of IPORA is validated through comparisons with satellite sea surface temperature, altimetry data, observed currents, and other reanalyses. Compared to the control experiment, IPORA significantly reduces errors and improves interannual variability in temperature, salinity, sea level anomaly, and current fields. It also captures strong signals of sea level anomaly variability and reproduces the linear trend well.