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Where/when can we expect an improved skill from the knowledge of the SSTA?

Mo and Kalnay (1991) performed monthly integrations with the NMC global atmospheric model prescribing first climatological SSTs and then observed SST anomalies (fixed at the initial time). The comparison of skills showed that the prescription of SST anomalies

Then if were able to estimate the forcing direction in coupled anomalies we would be able to provide a priori regional skill.

An important objective of this pilot study is to test whether the statistics generated using the dynamical rule are consistent with other techniques. From this result, it is clear that as in several other papers it is the atmosphere that drives most of the anomalies in the extratropics, while the ocean drives the atmosphere in the tropics. The anomalies considered here are those that persisted continuously 15-days in the 5-day average data.

•The dynamical rule proposed by Mo and Kalnay (1991) to determine the forcing direction in locally coupled anomalies gives results consistent with previous studies and with the lag-correlation between 850mb RV and SST. Statistics of the annual number of locally coupled anomalies indicate that “ocean-driven” anomalies prevail in the tropics, while “atmosphere-driven” anomalies prevail in the extratropics. Similar distribution of the forcing direction is obtained with five-day average data from ERA14 and with monthly data. It remains to be shown how the distribution of ocean-driven anomalies depend on the season and with the ENSO phases.

•It remains to be shown how the distribution of ocean-driven anomalies depend on the season and with the ENSO phases.