University of Wollongong

About: University of Wollongong is a education organization based out in Wollongong, New South Wales, Australia. It is known for research contribution in the topics: Population & Graphene. The organization has 15674 authors who have published 46658 publications receiving 1197471 citations. The organization is also known as: UOW & Wollongong University.

The role of vegetation in the formation of anabranching channels in an ephemeral river, Northern plains, arid central Australia

Abstract: As the distribution and abundance of vegetation in drylands is often controlled by the greater availability of water along river channels, riparian vegetation has the potential to influence significantly dryland river form, process and behaviour. This paper demonstrates how a small indigenous shrub, the inland teatree (Melaleuca glomerata), influences the formation and maintenance of anabranching channels in a reach of the ephemeral Marshall River, Northern Plains, arid central Australia. Here, the Marshall is characterized by ridge-form anabranching, where water and sediment are routed through subparallel, multiple channels of variable size which occur within a typically straight channel-train. Channels are separated by channel-train ridges — narrow, flow-aligned, vegetated features — or by wider islands. By providing a substantial element of boundary roughness, dense stands of teatrees growing on channel beds or atop the ridges and islands influence flow velocities, flow depths and sediment transport, resulting in flow diversion, bank and floodplain erosion, and especially sediment deposition. Ridges and islands represent a continuum of forms, and their formation and development can be divided into a three-stage sequence involving teatree growth and alluvial sedimentation. 1 Teatrees colonize a flat, sandy channel bed, initiating the formation of ridges by lee-side accretion. Individual ridges grow laterally, vertically and longitudinally and maintain a geometrically similar streamlined (lemniscate) form that presents minimum drag. 2 Individual ridges grow in size, and interact with neighbouring ridges, causing the lemniscate forms to become distorted. Ridges in the lee of other ridges tend to be protected from the erosive effects of floods and survive, whereas individual teatrees or small ridges exposed to flow concentrated between larger ridges, tend to be removed. 3 Ridges lengthen, and coalesce with downstream ridges, eventually subdividing the channel-train into well-defined anabranches. This sequence turns a channel, initially obstructed with dense and chaotic stands of teatrees, into a well-organized system of ridge-form anabranches. In the moderate- to low-gradient Marshall River, which is colonized by an abundance of within-channel vegetation and subject to declining downstream discharges, this helps to minimize flow resistance, thereby maintaining an efficient water and sediment flux. Copyright © 2000 John Wiley & Sons, Ltd.

Sources, seasonality, and trends of southeast US aerosol: an integrated analysis of surface, aircraft, and satellite observations with the GEOS-Chem chemical transport model

Abstract: . We use an ensemble of surface (EPA CSN, IMPROVE, SEARCH, AERONET), aircraft (SEAC4RS), and satellite (MODIS, MISR) observations over the southeast US during the summer–fall of 2013 to better understand aerosol sources in the region and the relationship between surface particulate matter (PM) and aerosol optical depth (AOD). The GEOS-Chem global chemical transport model (CTM) with 25 × 25 km2 resolution over North America is used as a common platform to interpret measurements of different aerosol variables made at different times and locations. Sulfate and organic aerosol (OA) are the main contributors to surface PM2.5 (mass concentration of PM finer than 2.5 μm aerodynamic diameter) and AOD over the southeast US. OA is simulated successfully with a simple parameterization, assuming irreversible uptake of low-volatility products of hydrocarbon oxidation. Biogenic isoprene and monoterpenes account for 60 % of OA, anthropogenic sources for 30 %, and open fires for 10 %. 60 % of total aerosol mass is in the mixed layer below 1.5 km, 25 % in the cloud convective layer at 1.5–3 km, and 15 % in the free troposphere above 3 km. This vertical profile is well captured by GEOS-Chem, arguing against a high-altitude source of OA. The extent of sulfate neutralization (f = [NH4+]/(2[SO42−] + [NO3−]) is only 0.5–0.7 mol mol−1 in the observations, despite an excess of ammonia present, which could reflect suppression of ammonia uptake by OA. This would explain the long-term decline of ammonium aerosol in the southeast US, paralleling that of sulfate. The vertical profile of aerosol extinction over the southeast US follows closely that of aerosol mass. GEOS-Chem reproduces observed total column aerosol mass over the southeast US within 6 %, column aerosol extinction within 16 %, and space-based AOD within 8–28 % (consistently biased low). The large AOD decline observed from summer to winter is driven by sharp declines in both sulfate and OA from August to October. These declines are due to shutdowns in both biogenic emissions and UV-driven photochemistry. Surface PM2.5 shows far less summer-to-winter decrease than AOD and we attribute this in part to the offsetting effect of weaker boundary layer ventilation. The SEAC4RS aircraft data demonstrate that AODs measured from space are consistent with surface PM2.5. This implies that satellites can be used reliably to infer surface PM2.5 over monthly timescales if a good CTM representation of the aerosol vertical profile is available.

Challenging “Factor–Cluster Segmentation”

Abstract: The concept of market segmentation has been widely accepted and warmly embraced both by tourism industry and academia. In tourism research, this increased interest in segmentation studies has led to the emergence of a standard research approach. Most notably a concept referred to as “factor–cluster segmentation” has been broadly adopted. The aim of this article is to demonstrate that this approach is not generally the best procedure to identify homogeneous groups of individuals (market segments).

Quality of life and travel motivations: integrating the two concepts in the Grevillea Model

Abstract: Over the past three decades, two bodies of literature have developed relatively independently: Quality-of-Life research in Psychology and Travel Motivations research in Tourism. Yet, the constructs underlying these two bodies of research are strongly interrelated. This book chapter (1) reviews the Quality-of-Life research area with a specific focus on the role of vacations as a Quality-of-Life domain, (2) reviews prior work in the area of Travel Motivations with a specific focus on motivational segments which may be associated with differences in the importance people attribute to vacations in general, and (3) proposes a conceptual model, referred to as the Grevillea Model, which integrates heterogeneity in the population with respect to both the importance attributed to vacations and Travel Motivations.