Intercomparison of the LASCO-C2, SECCHI-COR1, SECCHI-COR2, and Mk4 Coronagraphs

In order to assess the reliability and consistency of white-light coronagraph measurements, we report on quantitative comparisons between polarized brightness [pB] and total brightness [B] images taken by the following white-light coronagraphs: LASCO-C2 on SOHO, SECCHI-COR1 and -COR2 on STEREO, and the ground-based MLSO-Mk4. The data for this comparison were taken on 16?April 2007, when both STEREO spacecraft were within 3.1^° of Earth??s heliographic longitude, affording essentially the same view of the Sun for all of the instruments. Due to the difficulties of estimating stray-light backgrounds in COR1 and COR2, only Mk4 and C2 produce reliable coronal-hole values (but not at overlapping heights), and these cannot be validated without rocket flights or ground-based eclipse measurements. Generally, the agreement between all of the instruments?? pB values is within the uncertainties in bright streamer structures, implying that measurements of bright CMEs also should be trustworthy. Dominant sources of uncertainty and stray light are discussed, as is the design of future coronagraphs from the perspective of the experiences with these instruments.     

Using a fluvial archive to place extreme flood sediment (dis)connectivity dynamics in context of a longer-term record

The aim of this study was to establish the source and provenance of sediments deposited in a large floodplain sink during extreme floods in the Lockyer Creek catchment, Australia, in 2011 and 2013. We place the sediment source patterns in context of the longer-term record to determine whether coarse-grained sediment sources (i.e., very fine sand to very coarse sand) and the spatio-temporal pattern of (dis)connectivity have changed over time. We do this by matching the geochemical properties and age structure of a sediment profile located in a downstream floodplain sink to the elemental composition of source sediments. One hundred and fifty-seven sediment samples from 20 sites across the catchment are analysed using X-ray fluorescence (XRF) spectrometry to compare the elemental ratio composition of the downstream floodplain sink to its source materials. We use Optically Stimulated Luminescence (OSL) dating to determine the age structure of the sediments in the floodplain sink. The northern tributaries and parts of the Lockyer River trunk stream are the primary sources of coarse sediment. These areas are connected (coupled) to the lower trunk stream and floodplain sediment sink. Southern tributaries are largely disconnected (decoupled) and supply little sediment to the floodplain sediment sink. This pattern of sediment source contribution has remained similar over the last 6.8 ka at least. Sediment sources as observed in the 2011 flood have predominated over the mid-late Holocene whilst those in the 2013 flood are rare.     

Time – Distance Analysis of the Emerging Active Region NOAA 10790

We investigate the emergence of Active Region NOAA 10790 by means of time?–?distance helioseismology. Shallow regions of increased sound speed at the location of increased magnetic activity are observed, with regions becoming deeper at the locations of sunspot pores. We also see a long-lasting region of decreased sound speed located underneath the region of the flux emergence, possibly relating to a temperature perturbation due to magnetic quenching of eddy diffusivity, or to a dense flux tube. We detect and track an object in the subsurface layers of the Sun characterised by increased sound speed which could be related to emerging magnetic-flux and thus obtain a provisional estimate of the speed of emergence of around 1 km?s^?1.     

Geochemistry and provenance of the Turquoise Bluff Slate,northeastern Tasmania: tectonic significance

The Ordovician Turquoise Bluff Slate in northeastern Tasmania is a 2?km-thick sequence of deep-marine siliceous black slates. It is dominated by meta-siltstones with bimodal grainsize distributions typical of turbidite T_E-1 and T_E-2 facies. The slates have high SiO₂ indicating they are hemipelagites. The high Ba and V indicate they were deposited in an anoxic environment associated with high oceanic productivity. All these features are common in muddy turbidites. U–Th–Pb dating of detrital monazite and authigenic xenotime in the slates supports previous evidence that the dominant cleavage, in this unit, formed during the Benambran Orogeny. The whole-rock composition of the slates is similar to black slates in the Adaminaby Group, NSW. A review of Paleozoic whole-rock compositions from the Lachlan Orogen confirms they all have trace element contents similar to average Australian shale. However, there are subtle differences in composition. The Turquoise Bluff Slate and other Mathinna Supergroup rocks from the Eastern Tasmania Terrane have higher average Cr content than similar age turbidites from Victoria and NSW. This probably reflects a small contribution from Tasmania Cambrian ultramafic rocks in the provenance. If this were correct, northeastern Tasmania was closer to western Tasmania in the Paleozoic than other provinces of the Lachlan Orogen, southeastern Australia. Other subtle features of the whole-rock composition of Paleozoic sedimentary rocks from the Lachlan Orogen indicate it may be possible to recognise provincial variations in composition that will provide new constraints on tectonic models of southeastern Australia.     

A search for posteclipse brightening of Io in 1973. I

Eight eclipse reappearances of the innermost Galilean satellite, Io, were observed during the fall of 1973. The measurements were made using photometers specially designed to cope with the problem of scattered light from Jupiter. Posteclipse brightening of Io was not detected and, if present, was less than our estimated detection threshold of about 0.02 mag.     

Spatial Pair-Copula Modeling of Grade in Ore Bodies: A Case Study

A real-world mining application of pair-copulas is presented to model the spatial distribution of metal grade in an ore body. Inaccurate estimation of metal grade in an ore reserve can lead to failure of a mining project. Conventional kriged models are the most commonly used models for estimating grade and other spatial variables. However, kriged models use the variogram or covariance function, which produces a single average value to represent the spatial dependence for a given distance. Kriged models also assume linear spatial dependence. In the application, spatial pair-copulas are used to appropriately model the non-linear spatial dependence present in the data. The spatial pair-copula model is adopted over other copula-based spatial models since it is better able to capture complex spatial dependence structures. The performance of the pair-copula model is shown to be favorable compared to a conventional lognormal kriged model.     

Making ends meet, in the household and on the planet

Policy-making in relation to sustainable development is usually at the national (or, in relation to climate change, the global) level, yet the consumption it seeks to modify takes place at the household level. If households all ‘made ends meet’ in the same way then the much-relied upon notion of per capita consumption would be valid and we could rely on ‘top-down’ modelling to guide policy. Cultural Theory, however, predicts that there are five socially viable ways of making ends meet, and that all of them will be found (in varying proportions) within any nation. This prediction has been tested on a sample of 220 British households and shown to be well supported. Top-down modelling, it is argued, has to give way to a constructive interplay between the reflexive policy-maker and a plurally responsive citizenry. This revised version was published online in August 2006 with corrections to the Cover Date.     

Improving at-site flood frequency analysis with additional spatial information: a probabilistic regional envelope curve approach

Extreme flood events have detrimental effects on society, the economy and the environment. Widespread flooding across South East Queensland in 2011 and 2013 resulted in the loss of lives and significant cost to the economy. In this region, flood risk planning and the use of traditional flood frequency analysis (FFA) to estimate both the magnitude and frequency of the 1-in-100 year flood is severely limited by short gauging station records. On average, these records are 42 years in Eastern Australia and many have a poor representation of extreme flood events. The major aim of this study is to test the application of an alternative method to estimate flood frequency in the form of the Probabilistic Regional Envelope Curve (PREC) approach which integrates additional spatial information of extreme flood events. In order to better define and constrain a working definition of an extreme flood, an Australian Envelope Curve is also produced from available gauging station data. Results indicate that the PREC method shows significant changes to the larger recurrence intervals (≥100 years) in gauges with either too few, or too many, extreme flood events. A decision making process is provided to ascertain when this method is preferable for FFA.