Responses of dissolved oxygen to Deep Depression BOB 04 based on satellite and Bio-Argo observations in the Bay of Bengal

Abstract

This work explores the responses of subsurface dissolved oxygen (DO) to “Wind Pump” impacts of Deep Depression (DD) BOB 04 (2014) with a pre-existing cyclonic eddy based on satellite and Bio-Argo observations in the central Bay of Bengal. Results show the combined influence of the pre-existing cyclonic eddy and DD BOB 04 shoaled the oxycline from 48 m to the shallowest depth 32 m two days after the DD BOB 04. With the pre-existing cyclonic eddy, BOB 04 induced DO decrease in the subsurface for a long time of 18 days. The strong saline stratification suppressed the chlorophyll enhancement along the DD track after its passage. However, this weak DD caused the significant subsurface DO decrease owing to the upwelling. This hovered DD with a pre-existing cyclonic eddy played an important role in governing the boundary of oxygen minimum zone.