Date of Award

1-1-2012

Document Type

Campus Access Dissertation

Department

Marine Science

First Advisor

Subrahmanyam Bulusu

Abstract

The importance of Indian Ocean circulation dynamics to the regional and global weather signatures is increasingly recognized at large partly due to improved ocean observations in the last few decades. Observational and modeling efforts are directed towards understanding the impact of intraseasonal variability and interannual variability on the monsoon variability.

A key component of better understanding for the region is the resolving of salt transport within a dynamic freshwater flux environment. The freshwater influx leads to intense salinity stratification in the regions like the Bay of Bengal (BoB) and helps maintain warmer surface temperature. The synoptic information on sea surface salinity (SSS) variability both in time and space is essential in tune with its counterpart, the sea surface temperature (SST) which is being measured by the satellites. Though ocean salinity is one of the most important variables in the oceanic and climate studies, a gap in the Indian Ocean observing system to date has been the scarcity of surface salinity data. This study involves the use of numerical model outputs and salinity derived from satellites and Argo floats to understand the freshwater and salt transport dynamics in the Indian Ocean. Salt advection in the top 5 m layer using the 1/12° high resolution HYbrid Coordinate Ocean Model (HYCOM) during 2003-06 showed that Ekman drift is more important than geostrophic component in the exchange of salt in the basins. Results of depth integrated transport using HYCOM output show southward salt transport in the surface waters and northward salt transport in bottom waters. This study emphasizes that

HYCOM SSS is a good proxy to compare the satellite-derived salinity. Additionally, the study on long term (1960-2008) salt transport using the Simple Ocean Data Assimilation (SODA) Reanalysis reveals seasonal reversal in the mean salt transport which is more pronounced in the northern Indian Ocean. On interannual scale, the Indian Ocean Dipole and El Niño Southern Oscillation events also influence salt transport variability. This study also analyzes the critical role of salinity in the formation of the Arabian Sea mini warm pool using Soil Moisture and Ocean Salinity (SMOS), HYCOM and Argo float data.

Rights

© 2012, Ebenezer S. Nyadjro

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