Changing Storm Temporal Patterns with Increasing Temperatures across Australia

Abstract

Abstract It is well known that as a consequence of climate change, higher temperatures are causing extreme precipitation events to intensify, leading to greater flooding. However, the relationship between temperature and the temporal distribution of precipitation within storms is not well understood, with limited research focus on precipitation event loading or where the bulk of the precipitation occurs within the storm duration. Here, we investigate the relationship between temperature and the temporal pattern of precipitation, with a focus on event loading. Historical trend analyses based on station observations reveal that precipitation events have become increasingly front loaded (i.e., a greater percentage of precipitation falling earlier in the storm) across Australia over the past six decades. This increased frontal loading of precipitation events coincides with increasing trends in representative storm temperatures, with higher temperatures associated with a greater proportion of short-duration convective events. Linking these precipitation events with the representative storm temperatures shows that precipitation events become more front loaded with increasing temperature across nearly all event durations and intensities, with the emphasis on shorter duration (<6 h) events in the tropics. There is a clear systematic shift toward more front-loaded temporal patterns of precipitation with increasing temperature, coupled with intensification of embedded bursts. These results have implications for potentially increased flooding, with hydrological applications needing to account for nonstationarity in the temporal pattern of precipitation. Significance Statement To date, there is very little understanding of how temporal patterns of precipitation events change with increasing temperatures. Here, we investigate the relationship between temperature and the temporal pattern of precipitation events with a focus on the timing of when the bulk of precipitation occurs (termed event loading). Our results indicate a clear systematic shift toward more front-loaded temporal patterns of precipitation with increasing temperature, coupled with intensification of embedded bursts. Greater shifts in temporal patterns of precipitation are observed for shorter-duration precipitation events, particularly in the tropics. The impact of changing temporal patterns of precipitation on flood estimation will require careful examination due to the risk of increased flood peaks.