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The atmosphere typically receives heat from the open tropical ocean; an exception is the western and central Arabian Sea during the summer monsoon season. This article analyzes in situ observations from buoys and ships and examines mechanisms responsible for the reverse sea-air interfacial heat flux that have yet to be addressed. Key factors are the horizontal advection of heat and the heat flux derived via mixing and entrainment of air from above the atmospheric mixed layer in a Richardson number regime where shear-driven mixing would not normally be expected. This study invites a fresh look at the physics of entrainment and mixing in the atmospheric boundary layer. The reverse heat flux observations offer an opportunity to test the efficacy of physics encapsulated in boundary layer parameterization schemes for coupled models. [ABSTRACT FROM AUTHOR]

Long-term time series of velocity, hydrographic, and turbulence fields were collected from a six-element subsurface mooring array in the southern Bay of Bengal. The moorings, deployed in December 2013 and recovered in August 2015, were entangled with commercial fishing nets and lines, while top subsurface buoys ended up being serendipitously closer to the surface than planned. In spite of these unexpected events, almost all the sensors and data were recovered. The moorings provided currents between 6 m and 500 m depths from acoustic Doppler current profilers, supplemented by hydrographic data and turbulent dissipation rates at selected depths. The observations captured the summer and winter monsoon currents, eddies, and intraseasonal oscillations. Near-surface currents as large as 1.75 m s-1 were observed in July 2014. Currents stronger than 0.5 m s-1 were confined to the upper 200 m. Observations of currents, temperature, and sea surface height (SSH) fields revealed eddylike features with positive and negative SSH anomalies (~20 cm) moving westward at speeds of about 0.1 m s-1. Intraseasonal oscillations with periods of 30 to 90 days were strongest near the surface. For the duration of the deployment, root-mean-square velocity fluctuations were about 0.1 m s-1 near the surface but decayed with depth and became nearly uniform (~0.03-0.06 m s-1) below 100 m. [ABSTRACT FROM AUTHOR]

The region surrounding Sri Lanka modulates monsoon-driven exchange between the Bay of Bengal and the Arabian Sea. Here, local circulation impacts the pathways followed by the boundary currents that drive exchange, thereby modulating mixing and water mass transformation. From 2013 to 2016, an international partnership conducted sustained measurements around the periphery of Sri Lanka, with the goal of understanding how circulation and mixing in this critical region modulate exchange between the Bay of Bengal and the Arabian Sea. Observations from satellite remote sensing, surface drifters, gliders, current meter moorings, and Pressure Inverted Echo Sounders capture seasonally reversing monsoon currents off the southern tip of Sri Lanka, trace the wintertime freshwater export pathway of the East India Coastal Current, and document the deflection of currents running along the east coast of Sri Lanka by cyclonic and anticyclonic eddies. Measurements also reveal energetic interleaving, indicative of mixing and stirring associated with these flows. Circulation inferred from satellite remote sensing and drifter tracks sometimes differs from that indicated by in situ sections, pointing to the need for observing systems that employ complementary approaches toward understanding this region. [ABSTRACT FROM AUTHOR]

The article focuses on the dedication of the training and capacity-building component for the ASIRI-Effects of Bay of Bengal Freshwater Flux on Indian Ocean Monsoon (EBOB) project in August 2016, and includes information on the courses taught by U.S. scientists and the participation of Sri Lankan university faculty members.