Summary of Abstract Submission

Abstract Submission No. IO50-08-0011PresentationPoster

HORIZONTAL GRADIENTS IN THE BAY OF BENGAL, AND THE RESULTANT MIXING

Ritabrata Thakur*1, Karthik Menon1, Debasis Sengupta2, Rama Govindarajan 1

1 TIFR Centre for Interdisciplinary Sciences, Hyderabad, India
2 Indian Institute of Science, Bangalore, India

ABSTRACT :

We seek to investigate the effect of horizontal stratification in oceans and the resultant formation of fronts, which has been observed to have a significant effect on mixing processes and marine life in the upper layers of an oceanic system. Satellite data as well as theoretical and computational models have established correlations between the presence of oceanic fronts and increased phytoplankton concentrations. It has been shown that frontal instabilities, leading to restratification, can have a detrimental effect on turbulent mixing. We wish to study mixing in the vicinity of propagating river-water fronts. During monsoon the heavy fresh water discharge causes a significant horizontal front, where fresh water meets more saline water in the upper ocean and changes the salinity and the SST over very short time scales. The resultant low salinity level observed in the Bay of Bengal is a subject of interest not just due to its effect on monsoonal variations and phytoplankton concentrations, but also because it raises several questions with regard to the apparent ineffectiveness of upper-ocean mixing in the region. We are investigating this anomaly by studying the mixing processes particular to the conditions prevalent in the Bay of Bengal, by using theoretical stability analysis as well as computer simulations of the fronts. To achieve this, we use a stability analysis code developed in-house and in addition we use the open-source flow solver, Gerris, to carry out simulations in order to understand the dynamics of the fronts.