A call for standardization of aeolian process measurements: moving beyond relative case studies

Progress in some areas of process‐based aeolian sediment transport research is hampered by limited opportunities for data comparison, synthesis, and integration. This is partially due to a lack of reliable comparison methods. Many comparison methods are forms of calibration that are either restrictive (e.g., time‐averages only) or non‐existent (e.g., for field‐based sediment transport thresholds or vertical mass flux profiles). It is believed that the adoption of standard methods for common measurements may improve inter‐study comparison, add value and longevity to data, and advance integrative modeling efforts. Examples of approaches in allied disciplines where standards are used routinely are reviewed and we discuss how the mutual benefits of standardized data could outweigh perceived disadvantages. Overall, the goal of this commentary is to encourage discussion, self‐assessment, and forethought with regard to measurement methods used in process‐based aeolian geomorphology. Copyright © 2011 John Wiley & Sons, Ltd.     

An international comparison of governmental disclosure of hydrocarbon spills from offshore oil and gas installations

The cumulative effect of accidental spills from oil and gas extraction in the marine environment can have significant impacts on marine wildlife. Oil and gas operators are typically required to report spill data as part of a regulatory process. We conducted a survey of the public disclosure of hydrocarbon spill data for four countries, Australia, Canada, United Kingdom and United States. There was significant variation in the spill data statistics that were publicly reported by the regulators. No country provided full disclosure of spill data or follow-up actions taken by the regulator on their website. The lack of disclosure of spill data is of concern because the scale of environmental effects is more difficult to assess, insufficient information is available to assess the accuracy of predictions made in the environmental assessment process, and without consistency of spill reporting there is no method to compare regional differences of spill rates.     

‘Snake River (SR)-type’ volcanism at the Yellowstone hotspot track: distinctive products from unusual,high-temperature silicic super-eruptions

A new category of large-scale volcanism, here termed Snake River (SR)-type volcanism, is defined with reference to a distinctive volcanic facies association displayed by Miocene rocks in the central Snake River Plain area of southern Idaho and northern Nevada, USA. The facies association contrasts with those typical of silicic volcanism elsewhere and records unusual, voluminous and particularly environmentally devastating styles of eruption that remain poorly understood. It includes: (1) large-volume, lithic-poor rhyolitic ignimbrites with scarce pumice lapilli; (2) extensive, parallel-laminated, medium to coarse-grained ashfall deposits with large cuspate shards, crystals and a paucity of pumice lapilli; many are fused to black vitrophyre; (3) unusually extensive, large-volume rhyolite lavas; (4) unusually intense welding, rheomorphism, and widespread development of lava-like facies in the ignimbrites; (5) extensive, fines-rich ash deposits with abundant ash aggregates (pellets and accretionary lapilli); (6) the ashfall layers and ignimbrites contain abundant clasts of dense obsidian and vitrophyre; (7) a bimodal association between the rhyolitic rocks and numerous, coalescing low-profile basalt lava shields; and (8) widespread evidence of emplacement in lacustrine-alluvial environments, as revealed by intercalated lake sediments, ignimbrite peperites, rhyolitic and basaltic hyaloclastites, basalt pillow-lava deltas, rhyolitic and basaltic phreatomagmatic tuffs, alluvial sands and palaeosols. Many rhyolitic eruptions were high mass-flux, large volume and explosive (VEI 6–8), and involved H₂O-poor, low-δ¹⁸O, metaluminous rhyolite magmas with unusually low viscosities, partly due to high magmatic temperatures (900–1,050°C). SR-type volcanism contrasts with silicic volcanism at many other volcanic fields, where the fall deposits are typically Plinian with pumice lapilli, the ignimbrites are low to medium grade (non-welded to eutaxitic) with abundant pumice lapilli or fiamme, and the rhyolite extrusions are small volume silicic domes and coulées. SR-type volcanism seems to have occurred at numerous times in Earth history, because elements of the facies association occur within some other volcanic fields, including Trans-Pecos Texas, Etendeka-Paraná, Lebombo, the English Lake District, the Proterozoic Keewanawan volcanics of Minnesota and the Yardea Dacite of Australia. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. This paper constitutes part of a special issue dedicated to Bill Bonnichsen on the petrogenesis and volcanology of anorogenic rhyolites.     

The story of galaxy evolution in full colour

A Holy Grail of modern astronomy is understanding the origin of Edwin Hubble's morphological sequence of galaxy types. What made some collapsing gas clouds turn into elegant spiral systems like our own Milky Way, whereas others became smooth, featureless ellipticals? More fundamentally, does the taxonomic scheme introduced by Hubble in the 1920s have any physical relevance? The Space Telescope that bears Hubble's name is providing answers to these and other questions in the context of modern theories of structure formation.
Richard S Ellis, Roberto G Abraham, Jarle Brinchmann and Felipe Menanteau show how modern telescopes producing colourful images are pointing the way to understanding galaxy evolution.     

Intra-annual variability of urban effects on streamflow

While considerable research has established the impacts of urbanization on streamflow, there has been little emphasis on how intra-annual variations in streamflow can deepen the understanding of hydrological processes in urban watersheds. This study fills this critical research gap by examining, at the monthly scale, correlations between land-cover and streamflow, differences in streamflow metrics between urban and rural watersheds, and the potential for the inflow and infiltration (I&I) of extraneous water into sewers to reduce streamflow. We use data from 90 watersheds in the Atlanta, GA region over the 2013–2019 period to accomplish our objectives. Similar to other urban areas in temperate climates, Atlanta has a soil-water surplus in winter and a soil-water deficit in summer. Our results show urban watersheds have less streamflow seasonality than do rural watersheds. Compared to rural watersheds, urban watersheds have a much larger frequency of high-flow days during July–October. This is caused by increased impervious cover decreasing the importance of antecedent soil moisture in producing runoff. Urban watersheds have lower baseflows than rural watersheds during December–April but have baseflows equal to or larger than baseflows in rural watersheds during July–October. Intra-annual variations in effluent data from wastewater treatment plants provide evidence that I&I is a major cause of the relatively low baseflows during December–April. The relatively high baseflows in urban watersheds during July–October are likely caused by reduced evapotranspiration and the inflow of municipal water. The above seasonal aspects of urban effects on streamflow should be applicable to most urban watersheds with temperate climates.     

Searching for relic neutralinos using neutrino telescopes

Neutrino telescopes of large area offer the possibility of searching for indirect signals of relic neutralinos in the galactic halo, due to annihilations in the Sun or the Earth. Here we investigate the sensitivity, using a supergravity scheme where the soft scalar mass terms are not constrained by universality conditions at the grand unification scale. We first discuss in which regions of the supersymmetric parameter space the neutralino may be considered as a good candidate for cold dark matter. The discovery potential of the search using neutrino telescopes is then compared to that of the direct search for relic neutralinos.     

Strong size evolution of the most massive galaxies since z∼ 2

Using the combined capabilities of the large near-infrared Palomar/DEEP-2 survey, and the superb resolution of the Advanced Camera for Surveys HST camera, we explore the size evolution of 831 very massive galaxies  ( M _⋆≥ 10¹¹ h ⁻²₇₀ M_⊙)  since   z ∼ 2  . We split our sample according to their light concentration using the Sérsic index n . At a given stellar mass, both low  ( n < 2.5)  and high  ( n > 2.5)  concentrated objects were much smaller in the past than their local massive counterparts. This evolution is particularly strong for the highly concentrated (spheroid like) objects. At   z ∼ 1.5  , massive spheroid-like objects were a factor of 4 (±0.4) smaller (i.e. almost two orders of magnitudes denser) than those we see today. These small sized, high-mass galaxies do not exist in the nearby Universe, suggesting that this population merged with other galaxies over several billion years to form the largest galaxies we see today.