The intermediate water in the Philippine Sea

Abstract

The dimensional and temporal distribution of Antarctic Intermediate Water (AAIW) and North Pacific Intermediate Water (NPIW) in the Philippine Sea were explored using Argo profiles and gridded Argo data. As the salinity minimum of intermediate water from mid-high latitude of the southern and northern hemisphere of the Pacific Ocean, the properties of AAIW and NPIW merge at about 10°N with different properties in the Philippine Sea. The core of AAIW is located below 600 dbar with potential density of 27 ≤ σθ ≤ 27.3 kg/m3 and salinity of 34.5 ≤ S ≤ 34.55. The core of NPIW is located between 300-700 dbar with potential density of 26.2 ≤ σθ ≤ 27 kg/m3 and salinity of 34 ≤ S ≤ 34.4. The volume of AAIW and NPIW during January 2004 to December 2017 is negatively correlated. The time series of AAIW and NPIW is dominated by significant periods of 6 and 8 months, respectively. The variations of AAIW and NPIW are mainly affected by volume transport through a 130°E section by the North Equatorial Current (NEC) and North Equatorial Undercurrent (NEUC).