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Abstract

Global mean sea level has been rising and is attributed to anthropogenic climate change forcing. The causes are mainly thermal expansion due to ocean warming and addition of water mass into the ocean from melting of land ice. Regional sea levels can deviate significantly from global mean sea level due to different processes at various spatiotemporal scales. In this study, we examine Australian sea levels and underlying mechanisms based on observations from 1880s to current, including direct sea level measurements by in-situ tide gauges and satellite altimetry, as well as other relevant oceanic and atmospheric observations. We focus on three aspects to explain the regional distribution of Australian sea levels. Firstly, we examine the connection of sea levels with modes of climate variability (e.g., ENSO) and driving physical processes (e.g., wave propagation). Secondly, the regional sea level budget from 1966 to present from selected tide gauges are analysed to identify the dominant factors for sea level trends, including ocean dynamics, sea level fingerprints, vertical land movement and inverse barometer effect. Thirdly, the connection between Australian sea levels and ocean gyre circulation and boundary currents (such as the South Pacific subtropical ocean gyre and East Australian Current) are identified, focusing on coastal sea levels in response to strength and position of ocean gyres and boundary currents. Findings from this historical study improve our understanding of sea level changes and variability around Australia, which will help us to project future sea level changes in coming decades with more confidence and reliability.