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The eastern seaboard of Australia (ESA), shown on the left, is roughly the area between the east coast and the Great Dividing Range.
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Context 1
... New South Wales (NSW) government funded ESCCI commenced in 2007 to address the knowledge gaps associated with the causes and impacts of ECLs and to better understand current and future ECL related risks. ESCCI aims to under- stand the climate of the ESA (roughly the area between the east-coast and the Great Dividing Range; see Figure 1), the effect of climate change on the ESA, and the implications for climate change adaptation in the ESA. A major motivation for ESCCI is that the relatively narrow (~100 km east to west) coastal strip is poorly resolved in current genera- tion global climate models (grid resolution of ~250 km x 250 km) so it has proven difficult to infer climate change trends and impacts for the region. ...
Context 2
... with the previous results relating to the frequency and timing of ECLs it is clear that the different ECL sub-types also have different characteristics when it comes to the location that they typically occur in. Some geographical spread in the locations of different ECL sub-types is expected due to the way the ECL sub-types are defined (see Section 2.1) however the spatial variability illustrated in Figure 5, far more than what is suggested by the mean storm track shown in Figure 1 of Browning and Goodwin (2013), is particularly important for water resource management as even a small shift in the loca- tion of ECL events could mean that reservoir filling rainfall no longer falls over the catchment areas for important urban water supply systems within the ESA. Also important is the fact that some regions within the ESA are clearly influenced by multiple ECL sub-types (e.g. the regions under overlapping boxes in the entire ECL life-cycle, i.e. (iv), part of Figure 5). ...
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... ECLs are intense low-pressure systems which occur over the subtropical east coasts of Southern and Northern Hemisphere continents, including Australia (Hopkins and Holland, 1997;Speer et al., 2009;Kiem et al., 2016;Lockart et al., 2016;Parana Manage et al., 2016;Verdon et al., Verdon-Kidd et al., 2016). ECLs operate on subdaily to daily timescales, and while they occur throughout the year, they are most prominent in the cooler seasons (Kiem and Twomey, 2014;Kiem et al., 2016). ...
... ECLs are intense low-pressure systems which occur over the subtropical east coasts of Southern and Northern Hemisphere continents, including Australia (Hopkins and Holland, 1997;Speer et al., 2009;Kiem et al., 2016;Lockart et al., 2016;Parana Manage et al., 2016;Verdon et al., Verdon-Kidd et al., 2016). ECLs operate on subdaily to daily timescales, and while they occur throughout the year, they are most prominent in the cooler seasons (Kiem and Twomey, 2014;Kiem et al., 2016). These systems can be associated with gale-force winds, large seas, storm surges, heavy rainfall and flooding (Hopkins and Holland, 1997;Speer et al., 2009;Verdon-Kidd et al., 2016;Power and Callaghan, 2016a;2016b). ...
... It is therefore acknowledged that in the 48 hr prior to an ECL event the low-pressure system is not strictly and ECL, but rather the synoptic scale pattern which proves to be a fundamental component of the ECLs development. This assignment of rainfall differs to the work of Kiem et al. (2016) who assigned rainfall to ECLs only whilst in the Tasman Sea Domain. As such, of the 2,237 days of rainfall between 1979 and 2011 which was associated with an ECL, 947 of these days occurred prior to the low entering the Tasman Sea. ...
The Eastern Seaboard of Australia (ESA) has been identified as being different to the rest of Australia in terms of rainfall patterns. However, rainfall patterns within the ESA itself are not well understood. This study identifies Australian rainfall districts that exhibit similar (and different) temporal variation, with the primary aim being to determine if the ESA can be considered a homogenous region with respect to rainfall. The results (a) confirm that the ESA is different to the rest of Australia and (b) show that the ESA is not homogenous and that East Coast Lows (ECLs) are linked to this inhomogeneity. For winter (JJA) three separate divisions within the ESA are identified and at least two clear divisions are identified in other seasons. ECL sub‐types contribute to this inhomogeneity because each ECL sub‐type is associated with different spatio‐temporal rainfall patterns across the ESA. This is an important insight for natural resources management and emergency services within the heavily populated ESA because it demonstrates that existing climate related risks are different across the ESA. Further, the way climate risks change in the future is also likely to be inconsistent across the ESA. Future climate related risks will depend on how ECL behaviour (e.g., intensity, frequency, location, duration, path and geographical extent) changes. This reinforces the need for locally relevant and practically useful climate science information and adaptation strategies—as opposed to the State‐ or country‐wide information and adaptation approaches that are commonly used.
... A direction of further investigation is to assess how the impacts of different classes of ECLs such as hybrid or cold-core cyclones differ, in terms of wind, rainfall, or other variables along the lines of a similar analysis of Kiem et al. (2016) for cyclones with a different origin. ...
... One aspect is whether climate change will affect different classes of low pressure systems in similar or different ways (e.g., by altering the relative fraction or the spatial patterns of warm-core, hybrid, and cold-core systems). Such alteration can cause changes in the associated impacts if the impacts of different classes of cyclones differ substantially (Kiem et al. 2016). Furthermore, there are several indications of a poleward migration of tropical cyclone activity following the expansion of the tropics in a warmer climate (Walsh and Katzfey 2000;Lavender and Walsh 2011;Kossin et al. 2014;Parker et al. 2018;Studholme and Gulev 2018;Sharmila and Walsh 2018). ...
The subtropical part of the eastern Australian seaboard experiences intense cyclonic activity. The severe damage caused by the intense storms in the region, known as east coast lows (ECLs), has motivated a number of recent studies. Cyclones in this region appear to be driven by a combination of different (barotropic and baroclinic) formation mechanisms, consistent with the view emerging in the last decades that cyclones span a continuous spectrum of dynamical structures, with the barotropically driven tropical cyclone and the baroclinically driven extra-tropical cyclone being only the extremes of such spectrum. In this work we revisit the climatology of cyclone occurrence in the subtropical east coast of Australia as seen in a global reanalysis, systematically applying classification criteria based on the cyclone vertical structure and thermal core. Moreover, we investigate the underlying processes driving the cyclone rapid intensification by means of an atmospheric limited area energetics analysis. We show that ECLs have different spatial patterns according to the cyclone thermal structure, with the fraction of hybrid cyclones being larger towards the tropics and closer to the coast. Moreover, we find that explosively deepening cyclones in this region are driven by a different combination of processes with respect to the global case, with barotropic processes in the surrounding environment having a more dominant role in the energetics of cyclone rapid intensification. The findings of this work contribute to understanding the physical processes underlying the formation and intensification of Australian east coast lows and the associated coastal damage and risk.
... The hydroclimate of the Australian east coast is distinct from other regions of Australia and is characterised by the influence of the Eastern Australian Current and an extended coastal mountain range, known as the Great Dividing Range ( Hopkins and Holland 1997). The coastal area, east of the Great Dividing Range, responds differently to large scale ocean drivers and experiences higher rainfall variability than west of the Great Dividing Range ( Di Luca et al. 2016, Browning andGoodwin 2016;Kiem et al. 2016;Verdon-Kidd et al. 2010). Given that over 50% of Australia's population resides along the east coast of Australia, detailed studies are needed to improve our understanding about the rainfall variability that exists in this region. ...
... The hydroclimate of the Australian east coast is distinct from other regions of Australia and is characterised by the influence of the Eastern Australian Current and an extended coastal mountain range, known as the Great Dividing Range (Hopkins and Holland 1997 ). The coastal area, east of the Great Dividing Range, responds differently to large scale ocean drivers and experiences higher rainfall variability than west of the Great Dividing Range (Di Luca et al. 2016, Browning and Goodwin 2016; Kiem et al. 2016; Verdon-Kidd et al. 2010). Given that over 50% of Australia's population resides along the east coast of Australia, detailed studies are needed to improve our understanding about the rainfall variability that exists in this region. ...
This study tests the statistical properties of downscaled climate data, concentrating on the rainfall which is required for hydrology predictions used in water supply reservoir simulations. The datasets used in this study have been produced by the New South Wales (NSW) / Australian Capital Territory (ACT) Regional Climate Modelling (NARCliM) project which provides a dynamically downscaled climate dataset for southeast Australia at 10 km resolution. In this paper, we present an evaluation of the downscaled NARCliM National Centers for Environmental Prediction (NCEP) / National Center for Atmospheric Research (NCAR) reanalysis simulations. The validation has been performed in the Goulburn River catchment in the Upper Hunter region of New South Wales, Australia. The analysis compared time series of the downscaled NARCliM rainfall data with ground based measurements for selected Bureau of Meteorology rainfall stations and 5 km gridded data from the Australian Water Availability Project (AWAP). The initial testing of the rainfall was focused on autocorrelations as persistence is an important factor in hydrological and water availability analysis. Additionally, a cross-correlation analysis was performed at daily, fortnightly, monthly and annually averaged time resolutions. The spatial variability of these statistics were calculated and plotted at the catchment scale. The autocorrelation analysis shows that the seasonal cycle in the NARCliM data is stronger than the seasonal cycle present in the ground based measurements and AWAP data. The cross-correlation analysis also shows a poor agreement between NARCliM data, and AWAP and ground based measurements. The spatial variability plots show a possible link between these discrepancies and orography at the catchment scale.
East coast cyclones (ECCs) provide an essential reprieve from dry periods across eastern Australia. They also deliver flood‐producing rains with significant economic, social and environmental impacts. Assessing and comparing the influence of different types of cyclones is hindered by an incomplete understanding of ECC typology, given their widely variable spatial and temporal characteristics. This study employs a track‐clustering method (probabilistic, curve‐aligned regression model) to identify key cyclonic pathways for ECCs from 1950 to 2019. Six spatially independent clusters were successfully distinguished and further sub‐classified (coastal, continental and tropical) based on their genesis location. The seasonality and long‐term variability, intensity (maximum Laplacian value ± 2 days) and event‐based rainfall were then evaluated for each cluster to quantify the impact of these lows on Australia. The highest quantity of land‐based rainfall per event is associated with the tropical cluster (Cluster 6), whereas widespread rainfall was also found to occur in the two continental clusters (clusters 4 and 5). Cyclone tracks orientated close to the coast (clusters 1, 2 and 3) were determined to be the least impactful in terms of rainfall and intensity, despite being the most common cyclone type. In terms of interannual variability, sea surface temperature anomalies suggest an increased cyclone frequency for clusters 1 (austral winter) and 4 (austral spring) during a central Pacific El Niño. Furthermore, cyclone incidence during IOD‐negative conditions was more pronounced in winter for clusters 1, 2, 3— and clusters 4 and 5 in spring. All cyclones also predominantly occurred in SAM‐positive conditions. However, winter ECCs for clusters 1 and 3 had a higher frequency in SAM‐negative. This new typology of ECCs via spatial clustering provides crucial insights into the systems that produce extreme rainfall across eastern Australia and should be used to inform future hazard management of cyclone events.
This paper focus on the establishment of Geodetic Network in Nigeria which serve as the framework and basis for every spatially referenced system in the country. It explains the historical development of Nigeria geodetic network, its mode of establishment, data acquisition method, computation and adjustment principles. The use recent positioning satellites (GNSS) and its several methods were discussed with the Least Squares Adjustment techniques. Literatures on best practices were reviewed to identify gaps that need to be covered so as to have an accurate and efficient geodetic network in the Nigeria. The research is basically on principles and methodology on the establishment of Geodetic Network in Nigeria and silent on hardware and software selection for its establishment.
East Coast Lows (ECLs) are important weather systems that affect the eastern seaboard of Australia. They have attracted research interest for both their destructive nature and water supplying capability. In this paper, three objective ECL tracking methods are applied to the twentieth century reanalysis ensemble (20CR V2C) for the period of 1851-2014 to identify historical trends and variability in ECLs. While the ensemble mean is unsuitable for tracking ECLs, when all methods are applied to the full 56-member ensemble there is large agreement between tracking methods as to the low-frequency variability and trends in ECLs. The uncertainty between 56 ensemble members has dramatically decreased in recent decades. For comparison, the three tracking methods are also applied to ERA-I reanalysis dataset for the overlapping time period (1980-2009). The inter-annual variability and monthly distribution of ECLs agrees well between different reanalysis for each of tracking methods. The most recent decade has had relatively low numbers of ECLs compared to the previous century.
Along with global warming, drought disasters are occurring more frequently and are seriously affecting normal life and food security in China. Drought risk assessments are necessary to provide support for local governments. This study aimed to establish an integrated drought risk model based on the relation curve of drought joint probabilities and drought losses of multi-hazard-affected bodies. First, drought characteristics, including duration and severity, were classified using the 1953–2010 precipitation anomaly in the Taoerhe Basin based on run theory, and their marginal distributions were identified by exponential and Gamma distributions, respectively. Then, drought duration and severity were related to construct a joint probability distribution based on the copula function. We used the EPIC (Environmental Policy Integrated Climate) model to simulate maize yield and historical data to calculate the loss rates of agriculture, industry, and animal husbandry in the study area. Next, we constructed vulnerability curves. Finally, the spatial distributions of drought risk for 10-, 20-, and 50-year return periods were expressed using inverse distance weighting. Our results indicate that the spatial distributions of the three return periods are consistent. The highest drought risk is in Ulanhot, and the duration and severity there were both highest. This means that higher drought risk corresponds to longer drought duration and larger drought severity, thus providing useful information for drought and water resource manage-ment. For 10-, 20-, and 50-year return periods, the drought risk values ranged from 0.41 to 0.53, 0.45 to 0.59, and 0.50 to 0.67, respectively. Therefore, when the return period increases, the drought risk increases.
Climate variability, climate change and extreme events pose risks that need to be quantified and managed. Dry and hot conditions have notable impacts, and have a strong link to drought risk. Many extreme event analyses focus on one variable at a time. However, compound extremes, involving two or more climate variables, can have a disproportionately large impact. Thus integrated multivariate analyses are necessary to comprehensively assess climate impacts. Here we document 150 years of information about events with low monthly rainfall and high temperature for southeast Australia. The number of hot/dry months per year exhibits decadal variability and increasing trends. Long-term trends are more influenced by temperature than rainfall, consistent with a warming climate. The number of hot and dry consecutive events, defined as three to five consecutive months of compound events, is increasing. Our findings reinforce the need to consider definitions that include multivariate variables such as rainfall and temperature and/or other hydroclimate variables, where possible, when quantifying drought risk. Discussion on how the results could contribute to improvement in climate projection science in Australia or elsewhere is provided.
