A review of possible optical absorption features of oxygen molecules in the icy surfaces of outer solar system bodies

In this review we provide the data needed to interpret remote spectroscopic studies of O₂ molecules embedded in the icy surfaces of outer solar system bodies. O₂ produced by radiolysis has been seen in the gas phase and as the so-called ‘solid O₂’ trapped in the icy surfaces of Ganymede, Europa and Callisto. It may also have been indirectly observed on a number of objects by its radiolysis product, O₃. These observations indicate the importance of O₂ for understanding the chemical processes occurring on icy outer solar system surfaces. Therefore, the published absorption spectra of gaseous, liquid and solid O₂ and of O₂ embedded in H₂O ice are reviewed in some detail. Particular emphasis has been placed on the presentation of transition probabilities for the various O₂ spectral series so that their relative importances can be assessed when they are used for modelling the radiation chemistry occurring in such environments.     

Hydrogeophysical Methods for Analyzing Aquifer Storage and Recovery Systems

Hydrogeophysical methods are presented that support the siting and monitoring of aquifer storage and recovery (ASR) systems. These methods are presented as numerical simulations in the context of a proposed ASR experiment in Kuwait, although the techniques are applicable to numerous ASR projects. Bulk geophysical properties are calculated directly from ASR flow and solute transport simulations using standard petrophysical relationships and are used to simulate the dynamic geophysical response to ASR. This strategy provides a quantitative framework for determining site‐specific geophysical methods and data acquisition geometries that can provide the most useful information about the ASR implementation. An axisymmetric, coupled fluid flow and solute transport model simulates injection, storage, and withdrawal of fresh water (salinity ～500 ppm) into the Dammam aquifer, a tertiary carbonate formation with native salinity approximately 6000 ppm. Sensitivity of the flow simulations to the correlation length of aquifer heterogeneity, aquifer dispersivity, and hydraulic permeability of the confining layer are investigated. The geophysical response using electrical resistivity, time‐domain electromagnetic (TEM), and seismic methods is computed at regular intervals during the ASR simulation to investigate the sensitivity of these different techniques to changes in subsurface properties. For the electrical and electromagnetic methods, fluid electric conductivity is derived from the modeled salinity and is combined with an assumed porosity model to compute a bulk electrical resistivity structure. The seismic response is computed from the porosity model and changes in effective stress due to fluid pressure variations during injection/recovery, while changes in fluid properties are introduced through Gassmann fluid substitution.     

Climate,conflict, and social stability: what does the evidence say?

Are violent conflict and socio-political stability associated with changes in climatological variables? We examine 50 rigorous quantitative studies on this question and find consistent support for a causal association between climatological changes and various conflict outcomes, at spatial scales ranging from individual buildings to the entire globe and at temporal scales ranging from an anomalous hour to an anomalous millennium. Multiple mechanisms that could explain this association have been proposed and are sometimes supported by findings, but the literature is currently unable to decisively exclude any proposed pathway. Several mechanisms likely contribute to the outcomes that we observe.     

The Bunburra Rockhole meteorite fall in SW Australia: fireball trajectory,luminosity, dynamics,orbit, and impact position from photographic and photoelectric records

Abstract– We report an analysis of the first instrumentally observed meteorite fall in Australia, which was recorded photographically and photoelectrically by two eastern stations of the Desert Fireball Network (DFN) on July 20, 2007. The meteoroid with an initial mass of 22 kg entered the atmosphere with a low speed of 13.36 km s^?1 and began a luminous trajectory at an altitude of 62.83 km. In maximum, it reached ?9.6 absolute magnitude and terminated after a 5.7 s and 64.7 km long flight at an altitude of 29.59 km with a speed of 5.8 km s^?1. The angle of the atmospheric trajectory to the Earth’s surface was 30.9°. The first organized search took place in October 2008 and the first meteorite (150 g) was found 97 m southward from the predicted central line at the end of the first day of searching (October 3, 2008). The second stone (174 g) was recovered 39 m northward from the central line, both exactly in the predicted mass limits. During the second expedition in February 2009, a third fragment of 14.9 g was found again very close (～100 m) from the predicted position. Total recovered mass is 339 g. The meteorite was designated Bunburra Rockhole (BR) after a nearby landscape structure. This first DFN sample is an igneous achondrite. Initial petrography indicated that BR was a brecciated eucrite but detailed analyses proved that BR is not a typical eucrite, but an anomalous basaltic meteorite ( Bland et al. 2009 ). BR was delivered from an unusual, Aten type orbit (a < 1 AU) where virtually the entire orbit was contained within Earth’s orbit. BR is the first achondrite fall with a known orbit and it is one of the most precise orbits ever calculated for a meteorite dropping fireball.     

Shifts in African crop climates by 2050, and the implications for crop improvement and genetic resources conservation

Increased understanding of the substantial threat climate change poses to agriculture has not been met with a similarly improved understanding of how best to respond. Here we examine likely shifts in crop climates in Sub-Saharan Africa under climate change to 2050, and explore the implications for agricultural adaptation, with particular focus on identifying priorities in crop breeding and the conservation of crop genetic resources. We find that for three of Africa's primary cereal crops – maize, millet, and sorghum – expected changes in growing season temperature are considerable and dwarf changes projected for precipitation, with the warmest recent temperatures on average cooler than almost 9 out of 10 expected observations by 2050. For the “novel” crop climates currently unrepresented in each country but likely extant there in 2050, we identify current analogs across the continent. The majority of African countries will have novel climates over at least half of their current crop area by 2050. Of these countries, 75% will have novel climates with analogs in the current climate of at least five other countries, suggesting that international movement of germplasm will be necessary for adaptation. A more troubling set of countries – largely the hotter Sahelian countries – will have climates with few analogs for any crop. Finally, we identify countries, such as Sudan, Cameroon, and Nigeria, whose current crop areas are analogs to many future climates but that are poorly represented in major genebanks – promising locations in which to focus future genetic resource conservation efforts.     

The poverty implications of climate-induced crop yield changes by 2030

Accumulating evidence suggests that agricultural production could be greatly affected by climate change, but there remains little quantitative understanding of how these agricultural impacts would affect economic livelihoods in poor countries. Here we consider three scenarios of agricultural impacts of climate change by 2030 (impacts resulting in low, medium, or high productivity) and evaluate the resulting changes in global commodity prices, national economic welfare, and the incidence of poverty in a set of 15 developing countries. Although the small price changes under the medium scenario are consistent with previous findings, we find the potential for much larger food price changes than reported in recent studies which have largely focused on the most likely outcomes. In our low-productivity scenario, prices for major staples rise 10–60% by 2030. The poverty impacts of these price changes depend as much on where impoverished households earn their income as on the agricultural impacts themselves, with poverty rates in some non-agricultural household groups rising by 20–50% in parts of Africa and Asia under these price changes, and falling by significant amounts for agriculture-specialized households elsewhere in Asia and Latin America. The potential for such large distributional effects within and across countries emphasizes the importance of looking beyond central case climate shocks and beyond a simple focus on yields – or highly aggregated poverty impacts.     

Development and Application of a Method to Identify Salt Marsh Vulnerability to Sea Level Rise

Wetlands are commonly assessed for ecological condition and biological integrity using a three-tiered framework of landscape-scale assessment, rapid assessment protocols, and intensive biological and physiochemical measurements. However, increased inundation resulting from accelerated sea level rise (SLR) is negatively impacting tidal marsh ecosystem functions for US Northeast coastal wetlands, yet relative vulnerability to this stressor is not incorporated in condition assessments. This article assesses tools available to measure coastal wetland vulnerability to SLR, including measurements made as part of traditional rapid condition assessments (e.g., vegetation communities, soil strength), field and remote sensing-based measurements of elevation, VDatum, and Sea Level Affecting Marshes Model (SLAMM) model outputs. A vulnerability metric that incorporates these tools was calibrated and validated using recent rates of marsh vegetation losses (1972–2011) as a surrogate for future vulnerability. The metric includes complementary measures of elevation capital, including the percentage of high vs. low marsh vegetation, Spartina alterniflora height, elevation measurements, and SLAMM outputs that collectively explained 62% of the variability in recent rates of marsh vegetation loss. Stepwise regression revealed that all three elements (elevation, vegetation measures, and SLAMM outputs) explained significant and largely unique components of vulnerability to SLR, with the greatest level of overlap found between SLAMM outputs and elevation metrics. While soil strength varied predictably with habitat zone, it did not contribute significantly to the vulnerability metric. Despite the importance of determining wetland elevation above key tidal datums of mean sea level and mean high water, we caution that VDatum was found to perform poorly in back-barrier estuaries. This factor makes it difficult to compare elevation capital among marshes that differ in tidal range and poses accuracy problems for broad-scale modeling efforts that require accurate tidal datums. Given the pervasive pattern of coastal wetland drowning occurring in the Northeastern USA and elsewhere, we advocate that compilation of regional data on marsh habitats and vulnerability to SLR is crucial as it permits agencies to target adaptation to sites based on their vulnerability or mixture of habitats, it helps match sites to appropriate interventions, and it provides a broader regional context to site-specific management actions. Without such data, adaptation actions may be implemented where action is not necessary and to the disadvantage of vulnerable sites where opportunities for successful adaptation will be missed.     

The Pongola structure of southeastern Africa: The world's oldest preserved rift?

Rocks of the Pongola Supergroup form an elongate belt in the Archean Kaapvaal Craton of southern Africa. Because these rocks exhibit many features that are characteristic of rocks deposited in continental rifts, including rapid lateral variations in thickness and character of sediments, volcanic rocks that are bimodal in silica content, coarse, basement derived conglomerates and thick sequences of shallow water sedimentary facies associations, we suggest that the Pongola Supergroup was deposited in such a rift. The age of these rocks (approximately 3.0 Ga) makes the Pongola structure the world's oldest well-preserved rift so far recognized, and comparison of the Pongola Rift with other rifts formed more recently in earth history reveals striking similarities, suggesting that the processes that formed this rift were not significantly different from those that form continental rifts today.     

Starspot modelling of the RS CVn binary HK lacertae

Investigating more than 270 nightly mean magnitudes of the long-period RS CVn binary HK Lac, we can draw some conclusions about the nature of its complicated light variations. The mean brightness, the apparent photometric period, and the shape of the light curve all show strong variations. Analysis with a starspot model, assuming two large spots and a general uniform spottedness, indicates two comparably large spots which appear to have maintained their separate identities for the last 15 yr and drifted in longitude separation from each other smoothly by only about 45°. The phase of the two spots indicates both are rotating very nearly synchronously with the orbital motion, one slightly (0.025%) faster and the other slightly (0.080%) slower. the latitudes of the two spots, one farther above the equator and one closer to the equator, are consistent with solar-type differential rotation and yield an estimate of 25±12° for the co-rotating latitude. A correlation between mean spot latitude and instantaneous photometric period yields another estimate of 31±2°, in agreement with the first.