Journal of Physical Oceanography EARLY ONLINE RELEASE This is a preliminary PDF of the author-produced manuscript that has been peer-reviewed and accepted for publication. Since it is being posted so soon after acceptance, it has not yet been copyedited, formatted, or processed by AMS Publications. This preliminary version of the manuscript may be downloaded, distributed, and cited, but please be aware that there will be visual differences and possibly some content differences between this version and the final published version. The DOI for this manuscript is doi: 10.1175/JPO-D-18-0204.1 The final published version of this manuscript will replace the preliminary version at the above DOI once it is available. If you would like to cite this EOR in a separate work, please use the following full citation: George, J., P. Vinayachandran, V. Vijith, V. Thushara, A. Nayak, S. Pargaonkar, P. Amol, K. Vijaykumar, and A. Matthews, 2019: Mechanisms of barrier layer formation and erosion from in–situ observations in the Bay of Bengal. J. Phys. Oceanogr. doi:10.1175/JPO-D-18-0204.1, in press. © 2019 American Meteorological Society AMERICAN METEOROLOGICAL SOCIETY