The morphological response of foredunes at a breached barrier system to winter 2013/2014 storms on the southwest coast of Ireland

The level of storminess in Ireland during the winter of 2013/2014 was exceptional, the effects of which cost the Irish state in excess of €260 million in infrastructure repair and insurance claims. In Ireland, a lack of coastal process data from monitoring programmes means that the response of protective barrier coasts to such events remains largely un‐investigated. This study addresses this issue through an examination of the geomorphic impacts of recent storms, including those that occurred during the winter 2013/2014, on a breached barrier on the southwest coast of Ireland. Data from a two‐year terrestrial laser scanning (TLS) monitoring campaign shows that the winter 2013/2014 events caused a major (>50 m) dune recession at Rossbehy, County Kerry. Results from a simple linear regression analysis indicate storm duration plays an important role in the removal of foredunes at the study site. Given the fact that the frequency of intense storms in the vicinity of Ireland is forecast to increase within the next century, a scientific understanding of barrier response to such events is critical to inform sound management practices. Copyright © 2016 John Wiley & Sons, Ltd.     

Quasiperiodic Jovian Radio bursts: observations from the Ulysses Radio and Plasma Wave Experiment

The Ulysses flyby of Jupiter has permitted the detection of a variety of quasiperiodic magnetospheric phenomena. In this paper, Unified Radio and Plasma Wave Experiment (URAP) observations of quasiperiodic radio bursts are presented. There appear to be two preferred periods of short-term variability in the Jovian magnetosphere, as indicated by two classes of bursts, one with 40 min periodicity, the other with 15 min periodicity. The URAP radio direction determination capability provides clear evidence that the 40 min bursts originate near the southern Jovian magnetic pole, whereas the source location of the 15 min bursts remains uncertain. These bursts may be the signatures of quasiperiodic electron acceleration in the Jovian magnetosphere; however, only the 40 min bursts occur in association with observed electron bursts of similar periodicity. Both classes of bursts show some evidence of solar wind control. In particular, the onset of enhanced 40 min burst activity is well correlated with the arrival of high-velocity solar wind streams at Jupiter, thereby providing a remote monitor of solar wind conditions at Jupiter.     

VLF propagation loss to a buried seismometer

The propagation loss from a shallow underwater explosion to a buried vertically polarized seismometer over the frequency band between 3 and 15 Hz was measured during the 1983 Ngendei Experiment. The data was recorded in 5.5-km-deep water in the southwest Pacific with a triaxial borehole seismograph emplaced 50 m within the basaltic basement. It is found that the average power decays as r^-3 (r is slant range) beyond 30 km and that the propagation loss is minimal between 6-9 Hz. At shorter ranges, the propagation loss is more complicated and exhibits a stronger frequency dependence. Power in the first water wave is estimated for both buried and ocean-bottom sensors. The ocean-bottom power is approximately 7 dB higher than that recorded by the buried sensor, and both exhibit similar decay rates     

Assessing trophic adaptability is critical for understanding the response of predatory fishes to climate change: a case study of Pomatomus saltatrix in a global hotspot

There is a growing need to incorporate biotic interactions, particularly those between predators and their prey, when predicting climate-driven shifts in marine fishes. Predators dependent on a narrow range of prey species should respond rapidly to shifts in the distribution of their prey, whereas those with broad trophic adaptability may respond to shifts in their prey by altering their diet. Small pelagic fishes are an extremely important component of the diet of many marine predators. However, their populations are expected to shift in distribution and fluctuate in abundance as the climate changes. We conducted a comparative study of the seasonal diet of adult Pomatomus saltatrix over two periods (June–December 2006 and 2012) and examined the available data on small pelagic fishes biomass in a global hotspot (the coastal region of southern Angola, southern Africa) to gain an understanding of the tropic adaptability of the species. Despite a drop (630 000 t to 353 000 t) in the abundance of their dominant prey (Sardinella aurita) in the region, it remained the most important prey item during both study periods (Period 1 = 99.3% RI, Period 2 = 85.3% RI, where %RI is a ranking index of relative importance). However, the diet during Period 2 was supplemented with prey typically associated with the nearshore zone. The seasonal data showed that P. saltatrix were capable not only of switching their diet from S. aurita to other prey items, but also of switching their trophic habitat from the pelagic to the nearshore zone. These findings suggest that P. saltatrix will not necessarily co-migrate if there is a climate-driven shift in the distribution of small pelagic fishes (their dominant prey). Accordingly, understanding the trophic adaptability of predators is critical for understanding their response to the impacts of climate change.     

On the role of dust in the lunar ionosphere

Radio occultation measurements from the Soviet Luna 19 mission suggest that electron concentrations above the sunlit lunar surface can be significantly higher than that expected from either the photo-ionization of exospheric neutrals or any other well-known process. These measurements were used to infer the electron column concentrations above the lunar limb as a function of tangent height, which surprisingly indicated peak concentrations of ∼10³ cm⁻³ at ∼5 km altitude. It has been speculated that electrically charged exospheric dust could contribute to such electron populations. This possibility is examined here using the exospheric dust abundances inferred from Apollo 15 coronal photographs to estimate the concentration of electrons produced by photo- and secondary emission from dust. These estimates far exceed the electron concentrations predicted by any other suggested mechanism, and are within a factor of ≈20 of those inferred from the Luna 19 measurements. It is possible that this discrepancy is due to an under-estimate in dust grain capacitances and/or the presence of much higher exospheric dust abundances during the Luna 19 measurements. These results suggest that electrons emitted from exospheric dust could be responsible for the Luna 19 measurements, and that this process could dominate the formation and evolution of the lunar ionosphere.     

Regarding the possible generation of a lunar nightside exo-ionosphere

The non-condensing neutral helium exosphere is at its most concentrated levels on the cold lunar nightside. We show herein that these He atoms are susceptible to impact ionization from primary and secondary electrons flowing in the vicinity of the negatively-charged nightside lunar surface. The secondary electron beams are a relatively recent discovery and are found to be emitted from the nightside surface at energies consistent with the negative surface potential. The effect is to create an electron impact-created ionosphere in nightside regions, possibly especially potent within polar craters.     

Spatial and Temporal Ion Dynamics on a Complex Hydrological System: The Lower Luján River (Buenos Aires,Argentina)

The interplay of the geochemistry of the lower stretch of the Luján River is analyzed with its natural geomorphology (basin features), local hydrometeorology (tidal regime and “sudestada” events) and the impact of polluted tributaries. Major ions, dissolved heavy metals and limnological variables were analyzed using multivariate techniques. The water quality of the mainstream of the Luján River, flowing through urbanized and industrialized areas is strongly and positively influenced by the input of the Paraná River through deltaic watercourses and is negatively impacted after receiving the discharge from polluted watercourses. The longitudinal spatial variations evidenced major discontinuities in the Lower Luján Basin, showing clearly the riverine and the deltaic water influenced zones. Seasonal variations were also marked and were either temperature driven or associated with the estuarine cycle and the “sudestada”.     

Climate change simulated by full and mixed-layer ocean versions of CSIRO Mk3.5 and Mk3.0: Large-scale sensitivity

The CSIRO Mk3.5 coupled atmosphere-ocean model includes upgrades to atmospheric and oceanic processes that remove a cold bias of the earlier Mk3.0. The global mean warming over the 21st century from Mk3.5 is 3.1 K under the CMIP3 A1B scenario, some 25% larger than that from Mk3.0. Two mixed-layer ocean versions of Mk3.5 were constructed, and these are also more sensitive than Mk3.0. To elucidate these differences, a simple feedback analysis is extended to Mk3.5, using changes for doubled CO₂ in each model version. The net feedback for the low-mid latitude region is the main driver of the sensitivity contrast. The clear-sky component is consistently larger in Mk3.5, as is the increase in specific humidity, even after standardizing by the global warming. Cloud forcing provides a small positive feedback, which is stronger in cases that had larger declines in low-layer cloud. The net positive feedback for the higher-latitude region is larger in the coupled Mk3.5 than Mk3.0, which had more stable Arctic sea ice. However, some contrasts differed among the versions. As for Mk3.0, the surface warming in the coupled Mk3.5 is suppressed over that from the MLO case. Over the ocean, the pattern of suppression is similar to the change in energy flux into the surface in the coupled model. There is also a gradient of equatorial warming in the Asia-Pacific region that relates to the change in net convergence of heat transport by ocean currents. The effect of this pattern on regional rainfall is a focus of Part 2 of the study.     

The possibilities and pitfalls presented by a pragmatic approach to ecosystem service valuation in an arid biodiversity hotspot

Arid regions are home to unique fauna, flora, and vulnerable human populations, and present a challenge for sustainable land-use management. We undertook an assessment and valuation of three key services, grazing, tourism and water supply in the arid Succulent Karoo biome in western South Africa - a globally recognised biodiversity hotspot. We were looking for ways and values that could be used to promote conservation in this region through the adoption of sustainable land-use practices which have human welfare benefits. Our study adopted a variety of methods in valuing these services in developing ranges of values for these services. At the biome level, total annual values ranged from $ 19-114 million for grazing, $ 2-$ 20 million for tourism, and $ 300-3120 million for water. These values are generally low compared with values derived for other biomes and regions and do not adequately reflect known dependence and the importance of ecosystem services to the residents of this biome. The ecosystems here provide small but critical benefits enabling communities to sustain themselves and small changes in service levels can have major welfare effects. Highlighting these sensitivities will require finding more appropriate ways to link ecological and social factors.     

Aminostratigraphy of surface and subsurface Quaternary sediments,North Carolina coastal plain,USA

The Quaternary stratigraphy and geochronology of the Albemarle Embayment of the North Carolina (NC) Coastal Plain is examined using amino acid racemization (AAR) in marine mollusks, in combination with geophysical, lithologic, and biostratigraphic analysis of 28 rotasonic cores drilled between 2002 and 2006. The Albemarle Embayment is bounded by structural highs to the north and south, and Quaternary strata thin westward toward the Suffolk paleoshoreline, frequently referred to as the Suffolk Scarp. The Quaternary section is up to ～90 m thick, consists of a variety of estuarine, shelf, back-barrier, and lagoonal deposits, and has been influenced by multiple sea-level cycles. The temporal resolution of the amino acid racemization method is tested statistically and with the stratigraphic control provided by this geologic framework, and it is then applied to the correlation and age estimation of subsurface units throughout the region. Over 500 specimens (primarily Mercenaria and Mulinia) from the subsurface section have been analyzed using either gas chromatographic (GC) or reverse-phase liquid chromatographic (RPLC) techniques. The subsurface stratigraphic data are compared with AAR results from numerous natural or excavated exposures from the surrounding region, as well as results from NC beach collections, to develop a comprehensive aminostratigraphic database for the entire Quaternary record within the NC coastal system. Age mixing, recognized in the beach collections, is also seen in subsurface sections, usually where major seismic reflections or core lithology indicate the presence of stratigraphic discontinuities. Kinetic models for racemization are tested within the regional stratigraphic framework, using either radiocarbon or U-series calibrations or comparison with regional biostratigraphy. Three major Pleistocene aminozones [AZ2, AZ3, and AZ4] are found throughout the region, all being found in superposition in several cores. Each can be subdivided, yielding a total of at least eight stratigraphically and statistically distinct aminozones. Kinetic modeling, supplemented with local calibration, indicates that these aminozones represent depositional events ranging from ～80 ka to nearly 2 Ma. Three prominent seismic reflections are interpreted to represent the base of the early, middle, and late Pleistocene, respectively, roughly 2 Ma, 800 ka, and 130 ka. The large number of samples and the available stratigraphic control provide new insights into the capabilities and limitations of aminostratigraphic methods in assessing relative and numerical ages of Atlantic Coastal Plain Quaternary deposits.