Variability of the Subantarctic Mode Water Volume in the South Indian Ocean During 2004-2018
Abstract
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.
- Publication:
-
Geophysical Research Letters
- Pub Date:
- May 2020
- DOI:
- 10.1029/2020GL087830
- Bibcode:
- 2020GeoRL..4787830H
- Keywords:
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- subantarctic mode water;
- South Indian Ocean