Eddy Induced Trapping and Homogenization of Freshwater in the Bay of Bengal

Freshwater from rivers influences Indian summer monsoon rainfall and regional tropical cyclones by shallowing the upper layer warming subsurface ocean in Bay of Bengal. Here, we use situ satellite data with reanalysis products to showcase how river water can experience a significant increase salinity on subseasonal timescales. This involves trapping homogenization freshwater cyclonic eddy Bay. Specifically, October 2015, is shown enter particularly long-lived along its attracting manifolds within period two weeks. The itself quite unique that it lasted for 16 months where average lifespans are order 2-3 months. low results formation highly stratified surface layer. In fact, when freshest, has highest sea-level anomalies, spins fastest, supports strong lateral gradients salinity. Subsequently, observations reveal progressive relaxation anomalies month. particular, salty spirals in, pulled out across boundary. Lagrangian experiments elucidate this process, whereby horizontal chaotic mixing provides mechanism rapid timescale pathway distinct vertical likely be important eddy-rich