[A-OS19] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

[AOS19-P15] Interannual salinity variability in the Western Tropical Pacific and along the Kuroshio

*Chevarria Saravia Ricardo¹, Daniel Andres Lizarbe¹, Takeyoshi Nagai² (1.National Agrarian University La Molina, 2.Tokyo University of Marine Science and Technology)

A previous study using hydrographic data in the North Pacific shows an interannual variability of salinity, including a basin wide freshening during the period from 2009 through 2017. However, how the basin wide freshening occurs and its influences along the Kuroshio have been still unclear. In this study, daily reanalysis salinity dataset from 2003 through 2018 are analyzed using temporal filters to separate the interannual variability and decadal changes with special emphasize on the salinity anomaly from the western tropical North Pacific (WTNP) to the downstream. The decadal variabilities are obtained by 6-year moving average of the daily data. The interannual variabilities is then obtained by subtracting this averaged decadal data from the daily salinity. Our analysis using maps of lagged correlation coefficients for the interannual variations of salinity along the density surface between σ_θ=25-26 shows relatively high correlation coefficients between WTNP , i.e., the Kuroshio origin and the downstream along the Kuroshio. The advection of the salinity anomaly from the WTNP to the coast of Japan along the Kuroshio takes approximately 3 months. It is found that the variations of the wind stress curl over the WTNP drive the interannual salinity variability with a negative correlation.