Salinity records for the 1997–98 El Niño from Western Pacific corals

Abstract

Seasonal sea surface salinity (SSS) records can be of great value in reconstructing El Niño/Southern Oscillation (ENSO) variability in the equatorial Western and Central Pacific, a region where ENSO‐related evaporation and precipitation (E‐P) changes are dramatic. The δ 18 O values of coral skeleton (δ 18 O coral ) reflect seawater δ 18 O (δ 18 O seawater ) changes, which in tropical oceans are also generally influenced by E‐P changes. Therefore, δ 18 O coral is a good indicator of rainfall and ENSO variability. We present biweekly data from Palau, in the northern part of the Western Pacific Warm Pool, for the period 1998–2000, which indicate a strong quantitative relationship between δ 18 O coral , sea surface temperature, δ 18 O seawater and SSS. The coral skeletal δ 18 O values documented the SSS changes after the 1997–98 El Niño; therefore, δ 18 O coral can be used to estimate paleosalinity changes. However, the slope of the δ 18 O seawater ‐ SSS relationship cannot be assumed to be constant throughout the tropics, making site‐specific calibrations is essential.