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134365 - Seasonal Evolution of the Surface Layer Heat Balance.pdf (5.52 MB)

Seasonal evolution of the surface layer heat balance in the eastern subtropical Indian Ocean

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posted on 2023-05-20, 06:13 authored by Ajitha Cyriac, McPhaden, MJ, Helen PhillipsHelen Phillips, Nathaniel BindoffNathaniel Bindoff, Feng, M

The south Indian Ocean (SIO) is a region of strong air‐sea heat loss due to the unique ocean circulation pattern influenced by the Indonesian Throughflow. 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 colocated upper ocean and surface meteorology time series in the subtropical Indian Ocean. The mooring data are combined with other in situ and satellite data to examine the role of air‐sea fluxes and ocean heat transport on the evolution of mixed layer temperature using heat budget diagnostic models. Results show that on seasonal timescales, mixed layer heat storage in the eastern SIO is mostly balanced by a combination of surface fluxes and turbulent entrainment with a contribution from horizontal advection at times. Solar radiation dominates the seasonal cycle of net surface heat flux, which warms the mixed layer during austral summer (67 Wm‐2) and cools it during austral winter (‐44 Wm‐2). Entrainment is in good agreement with the heat budget residual for most of the year. Horizontal advection is spatially variable and appears to be dominated by the presence of mesoscale eddies and possibly annual and semi‐annual Rossby waves propagating from the eastern boundary. Results from the 2‐year mooring‐based data analysis are in reasonably good agreement with a 12‐year regional heat budget analysis around the mooring location using ocean reanalysis products.


Publication title

Journal of Geophysical Research: Oceans










Institute for Marine and Antarctic Studies


Wiley-Blackwell Publishing Inc.

Place of publication

United States

Rights statement

Copyright 2019 American Geophysical Union. Further reproduction or electronic distribution is not permitted.

Repository Status

  • Restricted

Socio-economic Objectives

Climate variability (excl. social impacts)

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