The Impacts of Climate Variability on New South Wales Australia Tidal Anomalies: Spatial Trends

Abstract:

New South Wales (NSW) often experiences periods of coastal inundation and estuarine flooding. These episodes are associated with a range of synoptic disturbances (Church et al., 2006). At the same time, the coast is facing progressive sea-level rise, which may exacerbate the effects of the atmospheric drivers on extreme water levels and associated flooding (White et al., 2014). This project aims to understand the relationship between Pacific Ocean climate drivers and extreme sea levels over sub-annual time scales along NSW. Monthly averaged means of tide anomalies obtained from ocean gauges along NSW coast were used to identify spatial and temporal trends in water levels, which were categorized in seasonal, interannual and decadal scales. The first stage of the project consisted of statistical analysis, to observe spatial trends over the seasonal scale on the tide anomalies along the NSW coast. On a similar manner, wavelet analyses were performed to observe temporal patterns by localizing periods with strong and significant signals of the climate drivers on the tide anomalies. Statistical analysis and continuous wavelet transforms were investigated between the monthly means, and indices of Pacific Climate mode indices (Southern Annular Mode, Canonical El Nino Southern Oscillation and El Nino Southern Oscillation Modoki). The effect of the three climate indices on the tidal anomalies decreases along the coast from south to north, with high significance for SAM and ENSO with frequencies varying from 6 months to 8 years. The ENSO Modoki has a low significance for the studied datasets as its frequency varies from 1 to 16 years. The results of this study will assist in forecasting and updating risk profiles for coastal flooding along NSW coast.