CoAuthors

Yosuke Fujii (Meteorological Research Institute, Japan); Masafumi Kamachi (Meteorological Research Institute, Japan)

For evaluation of observation systems such as ARGO floats, using an ocean data assimilation framework is common practices. The results may, however, depend on the ocean model adopted in the assimilation, and it requires a large computer resource when targeting eddy-scale variation over the whole global ocean. In this study, ARGO's capability of monitoring ocean variation, especially eddy-scale one, is evaluated more simply by using a statistical space-time correlation features estimated from 20-year altimetry data. Results of space-time OI applied to sea surface dynamic height anomaly (DHA) estimated from Argo are compared to results of the OI applied to SLA data. The results show that the equatorial instability waves and equatorial Kelvin waves are well captured by ARGO, probably due to large spatial correlation scales in the tropics. Eddies can be monitored also in the subtropical western North Pacific better than in other sub-tropical oceans. The OI results of DHA do not agree well with those of SLA in the Southern Ocean and in the subarctic North Atlantic. The number of ARGO floats is insufficient to monitor eddies in these regions (Figure). At least five times more floats are required to be deployed for monitoring eddies in these regions.