The impact of future changes in weather patterns on extreme sea levels over southern Australia

Abstract

[1] This study first compares two methods by which the global, variable resolution Cubic Conformal Atmospheric Model (CCAM) is forced by reanalysis over Australia. The methods are the spectral nudging and bias-corrected sea surface temperature (SST) forcing. Surface winds and sea level pressure are compared since these influence coastal sea levels. SST forcing was found to better preserve the mean and standard deviation of these quantities. Second, a hydrodynamic model is used to model sea levels over southern Australia over 1980Australia over -1999Australia over and 2080Australia over -2099 to investigate how changes in weather patterns affect extreme sea levels. Forcing from one Global Climate Model (GCM) and two CCAM simulations in which CCAM was used to downscale two GCMs over Australia with bias-corrected SST forcing (including the GCM considered in this study) were used. While there are differences in the spatial patterns of change between seasons over the modeled coastline between the three models, extreme sea levels were mostly lower in the future period over the southern mainland coastline from autumn to spring due to reduced westerlies in the climate models. The sea level changes around Tasmania varied from positive to negative depending on the model and season. The projected extreme sea level changes were within 10 cm of current climate values. This suggests that over southern Australia extreme sea level changes will be dominated by changes in mean sea level due to thermal expansion and ice sheet and glacier melt rather than changes in weather patterns.Citation: Colberg, F., and K. L. McInnes (2012), The impact of future changes in weather patterns on extreme sea levels over southern Australia,

Atmospheric Circulation Changes and their Impact on Extreme Sea Levels around Australia

“…However, since only two of the four climate model simulations simulated this change in the future climate, the finding is uncertain. Along the mainland south coast, there was a greater tendency for the models to indicate a reduction of ESLs in the future, particularly during winter which is also consistent with the finding of Colberg and McInnes [2012] using CMIP3 and regional climate models for the atmospheric forcing.…”

“…The model described by Colberg and McInnes [2012] is extended to cover the entire Australian coastline at 5 km resolution. A current climate (baseline) simulation is undertaken with tide and atmospheric forcing over the period 1981-2012 using reanalyses from 15 the NCEP Climate Forecast System Reanalyses (CFSR) [Saha et al, 2010].…”

“…As with Colberg and McInnes [2012], the model used in this study is the Rutgers version of the Regional Ocean Modeling System (ROMS) [Shchepetkin and McWilliams, 2005] configured to run in barotropic or 'depth-averaged' mode. The model grid spans the region shown in Figure 1 at 5 km resolution.…”

Introduction to the special issue: historical and projected climatic changes to Australian natural hazards

“…Colberg and McInnes 2012) and increases westward wave energy and littoral currents over eastern Victoria during summer (O'Grady et al 2015). Large-scale ocean/atmospheric process Nature of influence on Australian natural hazards Observed changes in the ocean/atmospheric process (since 1900), as reported by the IPCC Fifth Assessment Report (e.g.…”

Climate variability and change: a perspective from the oceania region

“…Coastal erosion is a problem that is of particular concern to Australian local government authorities, [49] who have responsibility for the protection of beaches, foreshores and sensitive environmental habitats such as mangroves. Whether to describe waterfront areas with mangroves as mangrove forests, with a strong implication of the need for forest conservation, or as mangrove swamps, with a strong implication of the need to eradicate and clean up such areas, can influence public opinion.…”