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Publication Title

Journal of Geophysical Research: Oceans






18 pp.


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, we have produced a 20th century Indian Ocean sea level reconstruction product using a new multivariate reconstruction technique. This technique uses sea level pressure and sea surface temperature in addition to sea level data to help constrain basin‐wide sea level variability by (1) the removal of large spurious signals caused as a result of insufficient tide gauge data specifically during the first half of the 20th century and (2) through its information on large‐scale climate modes such as El Niño‐Southern Oscillation and Indian Ocean Dipole. Basis functions generated by Cyclostationary Empirical Orthogonal Functions are used for the reconstruction. This new multivariate technique provides improved regional sea level variability estimates along with a longer record length in comparison to existing globally reconstructed sea level data. 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 20th century, providing a long sea level record for the study of Indian Ocean internal climate variability. 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.


An edited version of this paper was published by AGU. © 2020 American Geophysical Union.

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Data Availability

Article states: "The new reconstructed multivariate IO SL data have been made publicly available and can be downloaded online ( Tide gauge data are available from the Permanent Service for Mean Sea Level (PSMSL;, and the satellite altimetry data are available through the Archiving, Validation and Interpretation of Satellite Oceanographic (AVISO; ;‐surface‐height‐products/global.html). SST and SLP data are provided by NOAA/OAR/ESRL Physical Sciences Division, Boulder, Colorado, USA. The Extended Reconstruction SST (ERSST) version 5 SST data were downloaded from, and the NOAA Optimum Interpolation (OI) SST v2 data were downloaded online ( SLP data from the International Comprehensive Ocean‐Atmosphere Data Set (ICOADS) were download at and the NCEP‐NCAR Reanalysis 1 SLP data were download online ( The globally reconstructed SLA data by Hamlington, Leben, et al. (2014) can be downloaded at, Simple Ocean Data Assimilation (SODA) version 2.2.4 were downloaded from, and ECMWF Ocean ReAnalysis System 5 (ORAS 5) SL data and backward extension were downloaded online ("

Original Publication Citation

Kumar, P., Hamlington, B., Cheon, S. H., Han, W., & Thompson, P. (2020). 20th century multivariate Indian Ocean regional sea level reconstruction. Journal of Geophysical Research: Oceans, 125(10), 18 pp., Article e2020JC016270.


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