Seasonal evolution of the surface layer heat balance in the subtropical Indian Ocean — Australian Meteorological and Oceanographic Society
  1. Schedule
  2. 35. Variability and dynamics of Indo-Pacific ocean exchange and roles in air-sea coupling
  3. Seasonal evolution of the surface layer heat balance in the subtropical Indian Ocean

Seasonal evolution of the surface layer heat balance in the subtropical Indian Ocean (#160)

Ajitha Cyriac 1 2 , Michael McPhaden 3 , Helen Phillips 2 4 5 , Nathan Bindoff 2 4 6 , Ming Feng 5 7
  1. ARC Centre of Excellence for Climate System Science, Hobart, Tasmania, Australia
  2. University of Tasmania, Hobart, TASMANIA, Australia
  3. NOAA/Pacific Marine Environmental Laboratory, Seattle, Washington, United States of America
  4. ARC Centre of excellence in Climate Extremes, Hobart, Tasmania, Australia
  5. Centre for Southern Hemisphere Oceans Research, Hobart, Tasmania, Australia
  6. Antarctic Climate and Ecosystems, CRC , Hobart, Tasmania, Australia
  7. CSIRO Oceans and Atmosphere, IOMRC, Crawley, Western Australia, Australia

The south Indian Ocean (SIO) is a region with strong air-sea heat loss due to the unique ocean circulation pattern influenced by the Indonesian Throughflow (ITF). In this study, the seasonal variation of the surface layer heat budget in the eastern SIO is investigated  using 2 years of measurements from a mooring at 25◦S, 100◦E, the only upper ocean surface meteorology mooring in the subtropical Indian Ocean. This mooring analysis is combined with satellite, in situ and reanalysis products, and complemented by a 12 year regional  heat budget analysis around the mooring location. The role of air-sea fluxes and ocean advective heat transport on the evolution of mixed layer temperature during the study period is analyzed using mixed layer heat budget equations. It is found that on seasonal timescales, the mixed layer heat budget in the eastern SIO is mostly balanced by surface fluxes and horizontal advection. The net surface heat flux warms the mixed layer during austral summer and cools it during austral winter. But on average over the year, there is a net heat loss that must be balanced by oceanic processes of advection and mixing. Mean of the meridional advection of heat is stronger than zonal heat advection with a 2 cycle per year variability. Horizontal advection is moreover spatially variable likely due to the presence of Leeuwin Current (LC) eddies. This analysis improves our understanding of the seasonal variation of mixed layer heat balance in this climatically important region.

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