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The role of East Coast Lows on rainfall patterns and inter-annual variability across the East Coast of Australia



The Eastern Seaboard (ESB) of Australia is a distinct climate entity, with little relationship between rainfall in this area and the major drivers of rainfall elsewhere in Australia such as the El Niño-Southern Oscillation (ENSO). One potential cause is the influence of East Coast Lows (ECLs), major coastal weather systems that can produce a significant proportion of rainfall in this region. In this article, a novel approach is used to separate the ECL component of rainfall on the ESB from other sources of rainfall. This method is used to quantify the influence of ECLs on rainfall in this region, with ECLs responsible for 23% of rainfall in the ESB and 40% of widespread heavy rain events. While ECLs are particularly important in the southern ESB and during the cool season (May–October) they can occur in any month, particularly in northern areas of the ESB. ECLs are identified as a significant factor in the weakened relationship between ENSO and rainfall in the ESB, particularly in southern parts; however, these are not the only factor, with local topographic effects also likely to play a role. Copyright © 2013 Royal Meteorological Society