http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2255 This study examines the applicability of the assumption in flood frequency analysis that flood peaks are independent and identically distributed. It investigates the effect and extent of multidecadal variability for mainly coastal, eastern Australian flood data. The Interdecadal Pacific Oscillation (IPO) is a climate index which describes this long-term variability. The flood data were stratified by IPO value and flood frequency analyses performed. Analysis of the stratified flood distributions revealed that the IPO modulated the flood risk in New South Wales and southern Queensland, with flood quantiles being increased by a factor of approximately 1.7 during IPO negative periods, whereas little effect was detected for sites in north-east Queensland located approximately north of the Tropic of Capricorn. This IPO modulation of flood risk may be explained by multidecadal movements of regional convergence zones. Neglect of the IPO dependence on flood risk can lead to significant bias in long-run flood risk. 2013-03-12T05:39:15.564Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1849 Recent research has highlighted the persistence of multi-decadal epochs of enhanced/reduced flood risk across New South Wales (NSW), Australia. Recent climatological studies have also revealed multi-decadal variability in the modulation of the magnitude of El Niño/Southern Oscillation (ENSO) impacts. In this paper, the variability of flood risk across NSW is analysed with respect to the observed modulation of ENSO event magnitude. This is achieved through the use of a simple index of regional flood risk. The results indicate that cold ENSO events (La Niña) are the dominant drivers of elevated flood risk. An analysis of multi-decadal modulation of flood risk is achieved using the inter-decadal Pacific Oscillation (IPO) index. The analysis reveals that IPO modulation of ENSO events leads to multi-decadal epochs of elevated flood risk, however this modulation appears to affect not only the magnitude of individual ENSO events, but also the frequency of their occurrence. This dual modulation of ENSO processes has the effect of reducing and elevating flood risk on multi-decadal timescales. These results have marked implications for achieving robust flood frequency analysis as well as providing a strong example of the role of natural climate variability. 2012-03-12T07:27:05.390Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8917 Incorporating the influence of climate change and natural variability into stochastic hydrology is a priority for water resource planners who are being challenged by changing supply and demand patterns. The influence of large scale ocean-atmosphere climate mechanisms on Australia’s highly variable rainfall regimes is a valuable means for improving the ability of stochastic models to characterise hydrological variability. This paper re-evaluates the characterisation of Pacific Ocean hydro-climatological variability using multiple independent palaeoclimate records for the Interdecadal Pacific Oscillation (IPO) and the Pacific Decadal Oscillation (PDO). A suitable stochastic model for the persistence of phases of the IPO/PDO is developed. The simulations were incorporated into a seasonal stochastic rainfall model and applied to three sites on the East coast of Australia. The analysis in this paper provides an improved understanding of the decadal-scale variability of Pacific Ocean climate processes over the past 500 years. The findings could have considerable implications for water resource planners seeking to incorporate the influence of the large scale ocean-atmosphere climate mechanisms into water resource planning. 2011-09-12T05:40:09.339Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2429 This study investigates the influence of the El Niño–Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO) on rainfall and streamflow regimes of eastern Australia. An analysis of historical rainfall and streamflow data for Queensland (QLD), New South Wales (NSW), and Victoria (VIC) reveals strong relationships between these indices and seasonal rainfall and streamflow totals. Rainfall and streamflow in NSW and QLD are shown to be significantly enhanced during the La Niña phase of ENSO, with La Niña impacts diminishing as one moves south into VIC. In addition, the study shows that on a multidecadal timescale the negative phase of the IPO is associated with “wetter” conditions than the positive phase. Importantly, the already enhanced La Niña rainfall and streamflow is demonstrated to be even further magnified during La Niña events that occur in the IPO negative phase. This result is of particular importance as the influence of ENSO in VIC appears to be weak; however, the results indicate that some useful predictability of ENSO impacts can be achieved during the negative phase of the IPO for VIC. 2010-04-27T06:12:36.715Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5282 While strong relationships have previously been established between the El Niño/Southern Oscillation (ENSO) and climate variability in many parts of the world, previous analyses of ENSO impacts on European rainfalls have been variable and inconclusive. In this paper, the role and apparent interactions of a range of known teleconnections are assessed. It is shown that ENSO events do indeed appear to impact European rainfalls and that these impacts are likely to also depend on the concurrent state of the North Atlantic Oscillation (NAO) and the Pacific Decadal Oscillation (PDO). In particular, it is demonstrated that ENSO impacts most significantly on European wintertime rainfalls during positive (warm) phases of the PDO. 2010-04-27T04:33:48.897Z ]]>