Despite having some of the world's most densely populated and vulnerable coastlines, Indian Ocean sea level variability over the past century is poorly understood relative to other ocean basins, primarily due to the short and sparse observational records. In an attempt to overcome the limitations imposed by the lack of adequate observations, a new multivariate reconstruction framework was developed that uses sea level pressure and sea surface temperature in addition to sea level data to reconstruct 20^th century Indian Ocean sea level variability. Basis functions computed over the Indian Ocean and generated using Cyclostationary Empirical Orthogonal Functions help to capture regional variability, leading to an improvement in the reconstructed sea level estimates. The biggest advantage of using this multivariate reconstruction technique lies in its ability to reconstruct Indian Ocean sea level for the first half of the 20^th century. This will enable future studies to help improve the understanding of how sea level trends and variability can be modulated by internal climate variability in the Indian Ocean. Sea level over the tropical Indian Ocean (TIO) is known to be modulated by the climate modes of Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO). Using this newly reconstructed sea level dataset, the dominant mode of sea level variability over the TIO is shown to be related to concurrent IOD-ENSO events. Concurrent events produce a very strong sea level response with a spatial pattern opposite to that of the prevailing climatology and can persist for up to six months, having important dynamical implications. Additionally, a trend mode was also obtained, which is likely related to the increase in occurrence of positive IOD events over the 20^th century. These results seek to quantify the impact of climate modes on sea level variability over the Indian Ocean with the ultimate goal of helping the adaptation and mitigation efforts in the highly populated Indian Ocean rim countries facing the threat of sea level rise.

Praveen Kumar is a Ph.D. candidate in the Department of Ocean, Earth and Atmospheric Sciences at ODU (Dr. Tal Ezer, advisor) and part of the CCPO team working with Dr. Benjamin Hamlington. Using sea level reconstructions, his research seeks to quantify the impact of climate modes on sea level variability in the Indian Ocean. Praveen received his M.S. in Marine Sciences (Physical Oceanography) from Goa University, Goa, India in 2012. He then worked as a Junior Research Fellow at the CSIR-National Institute of Oceanography in Goa, India (2012-14) on the spatial and vertical variability of the SST seasonal cycle in the Northern Indian Ocean before joining ODU. The ultimate goal of his research is to help aid adaptation and mitigation efforts of sea level rise along the Indian Ocean rim countries.

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