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Large‐scale geomorphic drivers that operate at continental scale are often climate driven. Changes in land use can accelerate wind erosion. The range of land management practises within one land use can have dramatic effect on ground cover and wind erosion. This study uses meteorological observations, land use, land management and dust concentration measurements of 129 dust events recorded between 1990 and 2007 to describe a dust chronology of Mildura, in south‐eastern Australia. Frontal and frontal trough weather systems account for 74% of dust events. Furthermore, 88% of dust events come from rangelands in the northwest and the cropping lands to the southwest. The cropping areas to the southwest are the most common source of dust, accounting for 66% of events There is no relationship between rainfall and dust activity in this study, suggesting that land‐management practices, especially on cropping lands, over‐ride the controlling effect of rainfall. When cropping lands received above average rainfall in spring and summer during the 1990s, cultivation for weed control lead to rapid decline in ground cover that predisposed the land to wind erosion in following summer and autumn. In drought years, dust blows into Mildura from all directions suggesting that dust is climate driven rather than controlled by land use.

The roles of pre-frontal, frontal and post-frontal winds as the primary wind systems for dust entrainment and transport in Australia are well established. While the relevance of each system has been observed across different wind erosion events in central Australia, the entrainment of dust by all three winds during the passage of an individual front has not been demonstrated until now. Synoptic information, satellite aerosol and imagery, meteorological and dust concentration data are presented for a single case study erosion event in the lower Lake Eyre Basin. This event demonstrates variable dust transport in three different directions from one of the southern Hemisphere's most significant source regions, and the changing nature of the active dust pathways during the passage of a frontal system. While only a single dust event is considered, the findings show the complexity of mineral aerosol emission and transport patterns even within an individual dust outbreak. For the lower Lake Eyre Basin, this appreciation of pathway behaviour is significant for better understanding the role of aeolian inputs from the dominant Australian source to surrounding marine systems. In a wider context, the findings exhibit the detailed insights into major dust source dynamics that can be obtained from high resolution spatial and particularly temporal data, as used in combination. This work highlights the importance of adequately resolved data for the accurate determination of dust entrainment and transport patterns of major dust sources.

Australian meteorological observers started using the World Meteorological Organization (WMO) weather coding system in the 1950s. This system is still in use around the world today. However, observing and recording the weather in an organized and systematic manner had been ongoing for over 100 years prior to the adoption of this coding system, and much like Australia, most countries will have historical meteorological records. In this paper we compare the wind erosion of two of the greatest droughts in Australian recorded history; the World War II (WWII) Drought (1937–1945) and the Millennium Drought (2001–2009). To do this we analysed previously unavailable meteorological observer records from the Australian Bureau of Meteorology (ABM). Wind erosion records, mostly in long-hand written form, were translated to the modern WMO coding system for the WWII Drought and compared with the wind erosion of Australia's recently-ended Millennium Drought, one of the longest and harshest on record. We quantify wind erosion using Dust Event Days (DED) and a modified version of a published Dust Storm Index (DSI) to show that wind erosion during the WWII Drought was up to 4.6 times higher than during the Millennium Drought. This study has international significance because it demonstrates a methodology for tracking changes in wind erosion over the past 75 years based on observer records available in every country with a history of organized weather observation. Copyright © 2014 John Wiley & Sons, Ltd.

Soil erosion redistributes soil organic carbon (SOC) within terrestrial ecosystems, to the atmosphere and oceans. Dust export is an essential component of the carbon (C) and carbon dioxide (CO(2)) budget because wind erosion contributes to the C cycle by removing selectively SOC from vast areas and transporting C dust quickly offshore; augmenting the net loss of C from terrestrial systems. However, the contribution of wind erosion to rates of C release and sequestration is poorly understood. Here, we describe how SOC dust emission is omitted from national C accounting, is an underestimated source of CO(2) and may accelerate SOC decomposition. Similarly, long dust residence times in the unshielded atmospheric environment may considerably increase CO(2) emission. We developed a first approximation to SOC enrichment for a well-established dust emission model and quantified SOC dust emission for Australia (5.83 Tg CO(2)-e yr(-1)) and Australian agricultural soils (0.4 Tg CO(2)-e yr(-1)). These amount to underestimates for CO(2) emissions of ≈10% from combined C pools in Australia (year = 2000), ≈5% from Australian Rangelands and ≈3% of Australian Agricultural Soils by Kyoto Accounting. Northern hemisphere countries with greater dust emission than Australia are also likely to have much larger SOC dust emission. Therefore, omission of SOC dust emission likely represents a considerable underestimate from those nations' C accounts. We suggest that the omission of SOC dust emission from C cycling and C accounting is a significant global source of uncertainty. Tracing the fate of wind-eroded SOC in the dust cycle is therefore essential to quantify the release of CO(2) from SOC dust to the atmosphere and the contribution of SOC deposition to downwind C sinks.

Soil erosion is an important component of the global carbon cycle. However, little attention has been given to the role of aeolian processes in influencing soil organic carbon (SOC) flux and the release of greenhouse gasses, such as carbon dioxide (CO2), to the atmosphere. Understanding the magnitude and mechanisms of SOC enrichment in dust emissions is necessary to evaluate the impact of wind erosion on the carbon cycle. This research examines the SOC content and enrichment of dust emissions measured using Big Spring Number Eight (BSNE) wind‐vane samplers across five land types in the rangelands of western Queensland, Australia. Our results show that sandy soils and finer particulate quartz‐rich soils are more efficient at SOC emission and have larger SOC dust enrichment than clay‐rich aggregated soils. The SOC enrichment ratios of dusts originating from sites with sand‐rich soil ranged from 2·1–41·9, while the mean enrichment ratio for dusts originating from the clay soil was 2·1. We hypothesize that stronger inter‐particle bonds and the low grain density of the aggregated clay soil explain its reduced capacity to release SOC during saltation, relative to the particulate sandy soils. We also show that size‐selective sorting of SOC during transport may lead to further enrichment of SOC dust emissions. Two dust samples from regional transport events were found to contain 15–20% SOC. These preliminary results provide impetus for additional research into dust SOC enrichment processes to elucidate the impact of wind erosion on SOC flux and reduce uncertainty about the role of soil erosion in the global carbon cycle

Soil carbon stores amount to 54% of the terrestrial carbon pool and twice the atmospheric carbon pool, but soil organic carbon (SOC) can be transient. There is an ongoing debate about whether soils are a net source or sink of carbon, and understanding the role of aeolian processes in SOC erosion, transport and deposition is rudimentary. The impacts of SOC erosion by wind on the global carbon budget, and its importance for carbon accounting remain largely unknown. Current understanding of SOC losses to wind erosion is based on the assumption that the SOC content of eroded material is the same as that of the parent soils. However, measured enrichment factors for the SOC content of Australian dusts relative to parent soils show that the SOC content of dusts can be up to seven times (by weight) larger than that of source-area soils, with enrichment factors ranging from 1.67 to 7.09. Assuming dust emissions from the continent of ~110 Mt yr 1 , SOC dust emissions would be 0.13–4.65 Mt SOC yr 1 without enrichment but 0.94–7.77 Mt SOC yr 1 with enrichment; which represents an uncertainty of around 60%. Representing SOC enrichment within dust emission models will reduce uncertainty in estimates of the impact of wind erosion on SOC flux and provide an approach for the inclusion of wind erosion processes in carbon accounting systems.

This study simulates how spatial variations in particle-size emissions from a playa affect bulk and size-resolved dust concentration profiles during two contrasting wind erosion events (a small local and a large regional event) in the Channel Country, Lake Eyre Basin, Australia. The regional event had higher dust concentration as a result of stronger frontal winds and higher erodibility across the playa. For each event, two emission scenarios are simulated to determine if measured size-resolved dust concentration profiles can be explained by spatial variability in source area emissions. The first scenario assumes that particle-size emissions from source areas occur at a uniform rate, while the second scenario assumes that particle-size emissions vary between and within source areas. The uniform emission scenario, reproduced measured bulk dust concentration profiles (R2 = 093 regional and R2 = 081 local), however simulated size-resolved dust concentration profiles had poor statistical fits to measured size-resolved profiles for each size class (the highest were R2 = 05 regional and R2 = 03 local). For the differential particle-size emission scenario, the fit to the measured bulk dust concentration profiles is improved (R2 = 097 regional and R2 = 083 local). However, the fit to the size-resolved profiles improved dramatically, with the lowest being R2 = 089 (regional) and R2 = 080 (local). Particle-size emission models should therefore be tested against both bulk and size-resolved dust concentration profiles, since if only bulk dust concentration profiles are used model performance may be over-stated. As the source areas in the first 90 m upwind of the tower were similar for both events, the percentage contributions of each particle-size class to total emissions can be compared. The contribution of each particle-size class was similar even though the wind speed, turbulence and dust concentrations were significantly different; suggesting that the contribution of each particle-size to the total emitted dusts is not related to wind speed and turbulence.

Sediments often occur as non-normal size distributions composed of discrete, partially aggregated particle populations. These populations reflect provenance, dispersal pathways and their depositional environments. Recent experimental laboratory studies describing mud flocculation in turbulent marine systems prompted this investigation of the potential of aggregates to record size-sensitive transport dynamics in a terrestrial fluvial system. Here, sediment-size distributions in their natural condition of particle–aggregate mixtures are analysed by parametric statistics. A practical and freely available decompositional approach is outlined and field tested, which allows sediment to be viewed in both its conventional particulate form and as its naturally occurring mixture of transport-stable aggregates and elementary particles. From a sequence of upward-fining slack water couplets in the Flinders Ranges, South Australia, it is demonstrated that the characteristics, provenance and depositional history of fine-grained sediments consisting of particle-aggregate mixtures can best be understood fully by quantifying aggregation.

The entrainment, transport and deposition of aeolian dust are important processes affecting soil development at the margins of deserts. To assess accurately the impact of deposited aeolian dust on soil development, it is important not only to measure total dust deposition rates, but to distinguish additions of remotely and regionally sourced dust from locally derived material as well (which should not be viewed as new soil material as it is derived from aeolian re-mobilization of an existing soil). Because of the well-established relationship between dust particle-size and distance travelled from source, the particle-size distribution of deposited dusts can be used to identify the distance to probable source regions, in addition to identifying matching topsoil particle populations. Three dust traps were located along a transect of semi-arid south-eastern Australia, to measure aeolian dust deposition rates between late 2000 and late 2001. The particle-size distributions of selected dust deposits were measured and, with the aid of meteorological data, probable dust source regions determined. Particle-size distributions of the topsoils at each dust trap location were also measured to determine if any dust and soil particle populations matched. Although the sampling period was relatively short, and there was relatively little dust storm activity in this part of Australia during this time, a clear pattern of diminishing total dust deposition was measured downwind along the south-east dust path. Dust deposition rates were also moderate to low by global standards. Source regions of deposited dust were interpreted as being: (i) a combination of south-western and local sources; (ii) a combination of north-western and local sources; and (iii) a mixed source where dust was rained-out. The relative importance of these sources was correlated strongly with seasonal weather conditions, although the proportion of local dust in each deposit was greater at the arid (western) end of the transect. The effects of deposited dust on soil profile development are greatest at the western and central transect locations. At the western location, a fine-grained particle population distinctive of the south-western and north-western regional dusts and a coarse silt-sized particle population characteristic of local dusts, are also present in the topsoil, altering the texture of this Arenosol derived from dune sand. At the central location, where a Calcisol has formed in lacustrine lunette sediment, local dust of the same size as the dominant silt population of the topsoil continues to be deposited, while minor topsoil populations of very fine-grained silt match regional and long-distance dusts deposited at the site. Deposited dust appears to have been a less important soil development factor at the more humid eastern site because of the much smaller rates of dust deposition there. Nevertheless, a minor population of very fine silt particles in the Vertisol topsoil matches long-distance dusts deposited at the site, suggesting a small input of dust to this alluvial soil. The particle-size methodology used here has applications in other studies of dust contributions to peri-desert soils. In particular, particle-size distribution ‘smoothness’ may provide an indication of whether soils have simple or complex origins.

A review is presented of the aerosol-climate interaction with specific focus on the Australian region. The uncertainties associated with this interaction are much larger than those associated with greenhouse gases or other forcing agents, and are currently a major obstacle in climate-change research. However, new research suggests that aerosol effects are of comparable importance to greenhouse gases as a driver of recent climate trends in the Southern Hemisphere, including Australia. A significant new result from climate modelling is that anthropogenic aerosol over Asia affects meridional temperature gradients and atmospheric circulation, and may have caused an increase in rainfall over north-western Australia. Global ocean circulation provides another mechanism whereby aerosol changes in the Northern Hemisphere can affect climate in the Southern Hemisphere, suggesting an urgent need for further targeted studies using coupled ocean-atmosphere global climate models. To better model climate variability and climate change in the Australian region, more research is needed into the sources of aerosol and their precursors, their atmospheric distributions and transformations, and how to incorporate these processes robustly in global climate models (GCMs). The following priorities are suggested for further research in Australia linking aerosol observations and modelling: natural aerosol over the Southern Ocean, tropical biomass-burning aerosol in Indonesia and Australia, secondary organic aerosol (SOA) from volatile organic compounds (VOCs), wind-blown dust and modulation of rainfall by anthropogenic aerosol.

Environmental reporting and understanding of aeolian processes at different spatial and temporal scales require both extensive temporal and spatial data sources. The Bureau of Meteorology (BoM) SYNOP data have been used for environmental reporting in Australia by McTainsh and colleagues since 1998; however, with the current trend to replace meteorological observers with automated surface observation systems such as weather stations, these data sources are not sustainable. DustWatch was established to fill some of the gaps in the BoM network by strategically adding a community network of observers and instruments. Satellite imagery is also utilized when it is available. This paper outlines the nature of the DustWatch network, describes some of the educational and awareness outputs, outlines the types of data gathered and gives examples of how the data are being used both for environmental reporting and research into aeolian processes and activity. Copyright © 2008 John Wiley & Sons, Ltd.

The method for deriving a stage-discharge relationship has a significant impact on the shape of the river's rating curve. We compare rating curves for a single gauging station on a mutiple-channelled river in Australia compiled using three different methods – the Urban Runoff and Basin Systems (URBS) rainfall-runoff model, an empirically-based velocity-area method, and the predictive Hydrologic Engineering Centre-River Analysis System (HEC-RAS) computer model. The rainfall-runoff model was found to predict lower discharges for stage heights over 3.5 m than both the empirically-based velocity-area method and the HEC-RAS model. The empirically-based velocity-area model predicts similar discharges to the rainfall-runoff model for stage heights less than 3 m but much higher discharges for larger flood events. The HEC-RAS model predicts higher discharges than both other rating curves at all stage heights probably due to under-estimation of the impact of surface roughness on flow velocity. The three models are discussed with particular reference to their use on multiple-channelled rivers.

This paper evaluates the influence of natural sand particle characteristics on the amount and particle-size distributions of dust produced by aeolian abrasion. It contrasts with previous studies of aeolian abrasion by conducting experiments using: (i) whole sand samples, as opposed to selected size fractions; (ii) natural, mature dune sands, rather than artificial or freshly crushed material; and (iii) weathered sands that have acquired a superficial clay coating, instead of grains with clean surfaces. Whilst previous research has found clear, positive relationships between particle size, sorting, roundness and the amount of dust produced by aeolian abrasion, the relationships determined in this study show some variation according to the geomorphological context from which the original samples were obtained. The most important factor affecting the amount and particle-size characteristics of the dust produced was the presence of a clay coating on the grain surface that is removed by the abrasion process. The dust produced by this mechanism had a modal size of 2–5 µm and material

This paper describes a series of tests designed to evaluate the capacity of a personal computer (PC) based statistical curve-fitting program called MIX to quantify composite populations within multi-modal particle-size distributions. Three natural soil samples were analysed by a Coulter Multisizer, and their particle-size distributions analysed using MIX software to identify the modes, standard deviations and proportions of their composite populations. The particle-size distributions of the three natural soil samples were then numerically combined in equal proportions using a spreadsheet program to create synthetic particle-size distributions of known populations. MIX was then tested on the synthetic particle-size distributions to see if the modes and proportions it identified were similar to those modes and proportions known to characterize the synthetic particle-size distributions. The main outcome is that MIX can very accurately describe the modal particle size and proportions of the major composite populations within a particle-size distribution. However MIX has difficulty in identifying small populations (those contributing

Mean-sea-level-pressure patterns of the main atmospheric circulation for Australia were created using principal component analysis and non-hierarchical cluster analysis. The patterns are related to dust storm occurrence from 95 meteorological stations across Australia during the period 1960–99. Dust storm stations were separated into two groups with distinct dust storm seasons: the spring–summer (September–February) dust storm group and the summer–autumn (December–May) dust storm group. Spring–summer dust storms are most likely controlled by the timing of non-precipitation cold fronts over southern and central Australia and limited by summer precipitation. The summer–autumn dust storms are most likely controlled by the length of the driest period of the year. The stations of the first group are located mainly in the interior of the continent, and those of the second group are located mainly near the coastal regions of southern and western Australia. The location of the subtropical Indian Ocean high is shown here to influence dust storm occurrence during both seasons. A more westward displacement of this pressure centre in the Great Australian Bight allows cold fronts to enter the continent and increase the potential for dust storm activity. Copyright © 2004 Royal Meteorological Society

A series of experiments was conducted to determine the potential for aeolian abrasion of natural dune sands to produce fine particles (< 125 µm) by (1) the release of resident fines; (2) spalling, chipping and breakage of particles; and (3) the removal of grain surface coatings. Parent samples were obtained from the surfaces of four active continental dunes and abraded using a glass 'test tube' chamber for up to 120h. The fine particles produced by this abrasion process were trapped at varying time intervals and subject to detailed particle-size analyses using a Coulter Multisizer. The abrasion of untreated parent samples produced fine particles in one of two main size classes, 50 µm, but when the parent sample was sieved to exclude particles 63 µm) was dominant during the first 16 h of abrasion, then became less significant and is thought to be associated with the release of resident fines into suspension. The finest mode (

The sampling frequency in space and time is often inadequate to estimate the accuracy and precision of aeolian sediment transport. The problem stems from a lack of knowledge about the spatial and temporal scale of variation in aeolian transport and is compounded by a shortage of resources (aeolian sediment traps and labour). This study developed a geostatistical methodology for estimating sediment transport at unsampled locations and tested the extent to which it was dependent on sampling networks (nested, grid and random) and frameworks (mobile or static sampling framework between wind erosion events). Aeolian transport data were collected in an area of Australia influenced by wind erosion (Diamantina Lakes National Park, southwestern Queensland) to evaluate the combination of events used for mapping transport. Insufficient wind erosion events occurred to test sediment sampling strategies and hence simulated sampling was conducted using maps of sediment transport produced with existing models of aeolian sediment transport in the same study area. Independent validation data were used to test the estimation performance. The results suggested that sampling networks that did not include information on the spatial scale of variation (i.e. grid and random sampling) did not represent adequately the sediment transport population. In contrast, a bespoke nested sampling network performed consistently better than the other networks. Overall the static framework with a nested network was recommended for estimation and mapping of sediment transport with few resources and was likely to be especially important for use over large areas. This approach has the advantage of requiring only a single pooled within-event variogram for sediment transport to be used to derive the model parameters for kriging or stochastic simulation for each event. Copyright © 2003 John Wiley & Sons, Ltd.

Little is known about the spatial and temporal scales of variation in aeolian processes. Studies that aim to investigate surface erodibility often sample aeolian sediment transport at the nodes of a regular grid of arbitrary size. Few aeolian transport investigations have the resources to obtain sufficient samples to produce reliable models for mapping the spatial variation of transport. This study reports the use of an innovative nested strategy for sampling multiple spatial scales simultaneously using 40 sediment samplers. Reliable models of the spatial variation in aeolian sediment transport were produced and used for ordinary punctual kriging and stochastic simulated annealing to produce maps for several wind erosion events over a 25 km 2 playa in western Queensland, Australia. The results support the existence of a highly dynamic wind erosion system that was responding to possibly cyclic variation in the availability of material and fluctuations in wind energy. The spatial scale of transport was considerably larger than the small scale expected of the factors controlling surface erodibility. Thus, it appears that transport cannot be used as a surrogate of erodibility at the scale of this investigation. Simulation maps of transport provided considerably more information than those from kriging about the variability in aeolian sediment transport and its possible controlling factors. The proposed optimal sampling strategy involves a nested approach using ca 50 samplers. Copyright  2003 John Wiley & Sons, Ltd.

Dust storms are a major contributor to soil erosion in inland Australia, and the Simpson Desert-Channel Country region is one of the most active wind erosion regions. While information is available on wind erosion rates at the land-type level, little is known about the influence spatial variations in the erodibility within a land-type has on the resulting dust concentration profile. A Gaussian plume model, DSIS, is presented along with tower-based dust data, to describe the influence of different spatial combinations of dust sources areas, during three dust events on the Diamantina River flood-plain in Western Queensland, Australia.

PI kinematic trajectory model is used to investigate potential pathways of dust transport from Australia to New Zealand. Historically, these have been assumed to follow rather direct west-east trajectories spanning 2 to 3 days, often resulting in red snow events in the Southern Alps of New Zealand. However, results from the present study which examined the route taken by air parcels originating in southern Australia during dust storms on 24 and 25 May 1994, indicate that trans-Tasman dust transport trajectories are more diverse than previously thought, and display considerable variation during single events. These mon divergent pathways tie in more closely with aeolian dust sedimentation patterns identified by ocean coring in the Tasman Sea, and may account for the deposition of Australian dust on sub-Antarctic islands located well south of the Australian continent. Copyright 2000 John Wiley Sons, Ltd.

The pesticide endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide) has been detected in rivers in the cotton (Gossypium hirsutum L.)-growing area of northern New South Wales at a 5 yr mean (1991-1995) concentration of 0.06 mu g L-1. One pathway by which endosulfan reaches the riverine environment is transport on contaminated dust. Our objectives were to examine: (i) dust deposition from vehicular traffic on an unsealed road on a cotton farm, and around a cotton field in the 11 to 65 h period after endosulfan application; (ii) endosulfan deposition in the 11 to 65 h period after endosulfan application, and over a 3-mo period at on-farm and off-farm (nontarget) locations. Dust deposition rates from vehicular traffic varied from 0.013 g m(-2) vehicle(-1) at 1 m distance, to 0.002 g m(-2) vehicle(-1) at 100 m distance from an unsealed road (soil surface, no gravel added). The maximum endosulfan deposition in the 11 to 65 h post-spraying period was 95 mu g m(-2) at 5 m from the field. Over a 3-mo monitoring period (December 1996-March 1997), the average daily deposition rate of endosulfan was 0.16 mu g m(-2) d(-1) for the off-farm sites compared with 0.35 mu g m(-2) d(-1) for the on-farm site. As the measurement period was one of the wettest on record and the number of endosulfan applications was less-than-normal, the dust and endosulfan deposition results may be interpreted as minima.

The Coulter Multisizer has clearly defined strengths and weaknesses as a particle-sizing instrument. It is easier to operate than its Coulter predecessors, though less so than several of its competitors. The Multisizer is best suited to handle very small samples with a narrow particle-size range, such as aeolian dusts and other sediments available only in small quantities. For such samples, Multisizer analysis times are short, resolution is very high (256 size classes) and reproducibility is good. The Multisizer is less well suited to soils and other samples available in large quantities and with a broad particle-size range. For soil particle-size analyses a composite method is proposed involving: Multisizer (2–75 μm), Pipette ( 75 μm). © 1997 John Wiley & Sons, Ltd.

Grain-size characteristics and the flux of sediment transported by wind from a cultivated paddock in a Quaternary relict dune field are described. Sediments were collected at seven heights between 0.7 and 2.0 m. The distribution of sediment mass with height is explained by a power function (of the order of −1), which is highly skewed towards the bed. The distribution of

A climate index of effective soil moisture (Em Index) is proposed to describe the spatial extent and severity of wind erosion in Australia. The Em Index is calibrated against meteorological data on dust storm frequencies and is used to identify regions where wind erosion rates are increased by local environmental factors and/or human activities

Using meteorological records (1957–1984) in Australia, formal definitions are proposed of four types of dust event: dust storms, blowing dust, dust whirls, and dust haze. Australia-wide maps of the extent of these four dust event types are presented.