Salinity Variability Modes in the Pacific Ocean From the Perspectives of the Interdecadal Pacific Oscillation and Global Warming

Abstract

Ocean salinity is one of the most fundamental elements in physical oceanography and plays an important role in defining the state of the ocean. Salinity also offers key information on ocean geostrophic circulation and controls the formation of water masses and ocean stratification (Helber et al., 2010;Qin et al., 2015;Rao & Sivakumar, 2003;Wang & Zhang, 2012). Furthermore, ocean salinity also modulates ocean and climate variability (Katsura et al., 2013). Since ocean surface salinity is strongly dominated by freshwater exchange at the air-ocean interface (Yu, 2011), the variability of salinity can reflect the global freshwater budget and transport change, including the 86% of global evaporation that is from the ocean and the 78% of global precipitation that is from the air (Trenberth et al., 2007). On a global scale, over the last 50 years, sea surface salinity (SSS) changes reflect an intensification of the mean climatological SSS patterns (Sun et al., 2021). The amplifying surface salinity pattern induced by anthropogenic global warming is the result of the increased capacity of a warmer atmosphere (Held & Soden, 2006;Levang & Schmitt, 2015;Rhein et al., 2013). Thus, the climatological SSS tends to be the key fingerprint of the intensified global hydrological cycle. This means that the ocean freshens in precipitation-dominant areas and salinizes in evaporation-dominant areas (

Amplified vertical salinity contrasts in the northwestern tropical Pacific under ocean warming

“…The northward migration of outcrop lines accompanied by cold/fresh anomalies were induced by density-compensation mechanisms(Nonaka and Sasaki, 2007;Ogata and Nonaka, 2020;Wang et al, 2022;Shi et al, 2022). As demonstrated in Figures10b and c, a noticeable movement toward the pole at 𝜎 𝜃 =24.4 kg/m 3 was detected in the range of ventilation area due to a lightening density trend, especially after 2000.…”