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Variability of the Subantarctic Mode Water Volume in the South Indian Ocean During 2004–2018
Author(s) -
Hong Yu,
Du Yan,
Qu Tangdong,
Zhang Ying,
Cai Wenju
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl087830
Subject(s) - argo , mode water , ekman transport , shoal , volume (thermodynamics) , mixed layer , oceanography , environmental science , precipitation , climatology , geology , atmospheric sciences , biology , meteorology , geography , physics , subtropics , ocean gyre , fishery , upwelling , quantum mechanics
An analysis of Argo data reveals that the subantarctic mode water (SAMW) in the South Indian Ocean (SIO), characterized by a vertical potential vorticity (PV) minimum, decreases by 10% in volume from 2004 to 2018. Most of this decrease occurs at the 26.8–26.9 kg m −3 density range which forms southwest of Australia, while a slight volume increase occurs at 26.6–26.8 kg m −3 . Further analysis indicates that the weakening of the Mascarene High and westerly winds in the SIO reduces the evaporation‐precipitation, surface heat flux, and Ekman pumping and shoals the mixed layer southwest of Australia, which leads to a volume decrease at 26.8–26.9 kg m −3 in approximately 3 years. West of 90°E, the parameters exhibit the opposite change, leading to a volume increase at 26.6–26.8 kg m −3 . This result suggests that surface winds play an important role in the variability of the SIO SAMW volume during the Argo period.