The interstellar medium:the key component in galactic evolution and modern cosmology

The gases of the interstellar medium(ISM) possess orders of magnitude more mass than those of all the stars combined and are thus the prime component of the baryonic Universe. With L-band surface sensitivity even better than the planned phase one of the Square Kilometre Array(SKA1), the Five-hundredmeter Aperture Spherical radio Telescope(FAST) promises unprecedented insights into two of the primary components of ISM, namely, atomic hydrogen(HI) and the hydroxyl molecule(OH). Here, we discuss the evolving landscape of our understanding of ISM, particularly, its complex phases, the magnetic fields within, the so-called dark molecular gas(DMG), high velocity clouds and the connection between local and distant ISM. We lay out, in broad strokes, several expected FAST projects, including an all northern-sky high-resolution HI survey(22 000 deg2, 3′FWHM beam, 0.2 km s~(-1)), targeted OH mapping, searching for absorption and maser signals, etc. Currently under commissioning, the commensal observing mode of FAST will be capable of simultaneously obtaining HI and pulsar data streams, making large-scale surveys in both science areas more efficient.     

An uncertainty model for deep ocean single beam and multibeam echo sounder data

Comparing single beam and multibeam echo sounder data where surveys overlap we find that: 95% of multibeam measurements are repeatable to within 0.47% of depth; older single beam data can be at least as accurate as multibeam; single beam and multibeam profiles show excellent agreement at full-wavelengths longer than 4 km; archival sounding errors are not Gaussian; 95% of archival soundings in the northwest Atlantic are accurate to within 1.6% of depth; the 95th percentile error is about five times greater in pre-1969 data than in post-1968 data; many of the largest errors are located over large seafloor slopes, where small navigation errors can lead to large depth errors. Our uncertainty model has the form σ ² = a ² + (bz)² + (cs)², where 2σ is approximately the 95th percentile error, z is the depth, s is the slope, and a, b, c are constants we determine separately for pre-1969 and post-1968 data.     

Simulated soil water storage effects on streamflow generation in a mountainous snowmelt environment,Idaho, USA

Although soil processes affect the timing and amount of streamflow generated from snowmelt, they are often overlooked in estimations of snowmelt‐generated streamflow in the western USA. The use of a soil water balance modelling approach to incorporate the effects of soil processes, in particular soil water storage, on the timing and amount of snowmelt generated streamflow, was investigated. The study was conducted in the Reynolds Mountain East (RME) watershed, a 38 ha, snowmelt‐dominated watershed in southwest Idaho. Snowmelt or rainfall inputs to the soil were determined using a well established snow accumulation and melt model (Isnobal). The soil water balance model was first evaluated at a point scale, using periodic soil water content measurements made over two years at 14 sites. In general, the simulated soil water profiles were in agreement with measurements (P < 0·05) as further indicated by high R² values (mostly > 0·85), y‐intercept values near 0, slopes near 1 and low average differences between measured and modelled values. In addition, observed soil water dynamics were generally consistent with critical model assumptions. Spatially distributed simulations over the watershed for the same two years indicate that streamflow initiation and cessation are closely linked to the overall watershed soil water storage capacity, which acts as a threshold. When soil water storage was below the threshold, streamflow was insensitive to snowmelt inputs, but once the threshold was crossed, the streamflow response was very rapid. At these times there was a relatively high degree of spatial continuity of satiated soils within the watershed. Incorporation of soil water storage effects may improve estimation of the timing and amount of streamflow generated from mountainous watersheds dominated by snowmelt. Copyright © 2008 John Wiley & Sons, Ltd.     

North Atlantic extratropical and subpolar gyre variability during the last 120 years: a gridded dataset of surface temperature,salinity, and density. Part 1: dataset validation and RMS variability

We present a binned annual product (BINS) of sea surface temperature (SST), sea surface salinity (SSS), and sea surface density (SSD) observations for 1896–2015 of the subpolar North Atlantic between 40° N and 70° N, mostly excluding the shelf areas. The product of bin averages over spatial scales on the order of 200 to 500 km, reproducing most of the interannual variability in different time series covering at least the last three decades or of the along-track ship monitoring. Comparisons with other SSS and SST gridded products available since 1950 suggest that BINS captures the large decadal to multidecadal variability. Comparison with the HadSST3 SST product since 1896 also indicates that the decadal and multidecadal variability is usually well-reproduced, with small differences in long-term trends or in areas with marginal data coverage in either of the two products. Outside of the Labrador Sea and Greenland margins, interannual variability is rather similar in different seasons. Variability at periods longer than 15 years is a large part of the total interannual variability, both for SST and SSS, except possibly in the south-western part of the domain. Variability in SST and SSS increases towards the west, with the contribution of salinity variability to density dominating that of temperature in the western Atlantic, except close to the Gulf Stream and North Atlantic Current in the southwest area. Weaker variability and larger relative temperature contributions to density changes are found in the eastern part of the gyre and south of Iceland.

     

Ultramafic blocks from the ocean floor southwest of Australia

Samples dredged from the ocean floor near the junction of the Naturaliste Fracture Zone and the Diamantina Zone, 300 km southwest of Cape Leeuwin, Western Australia, contain 3- to 10-cm blocks of Cr-spinel lherzolites and Al-spinel-olivine clinopyroxenites. Both assemblages show textural evidence for deformation and recrystallization, with extensive development of kaersutite in one clinopyroxenite. The blocks are enclosed by clay and Fe-Mn oxide-rich fragmental material, which also contains a diverse detrital mineral suite and microfossils.Diopsides in the lherzolites are Na- and Cr-rich, with marked similarities to those of lherzolite nodules in alkaline basaltic suites. The Al- and Ti-rich diopsides of the clinopyroxenites are more magnesium than those of common pyroxene-rich nodules. The lherzolites are interpreted as upper mantle residues, while the clinopyroxenites probably represent partly recrystallized cumulates from high-temperature basaltic magmas traversing the lherzolite mantle. Both are thought to have been derived from an ultramafic body emplaced into the shallow crust near the Cretaceous/early Tertiary continent-ocean boundary off Australia.     

Re-specifying disaster risk: concepts,methods, and models

The discussion on the social-ecological dimensions of hazards is constantly evolving. This paper explores the trajectory of research relating to hazards and their impact on vulnerable human populations. Interpretations of disaster risk have included estimating losses in terms of human life and property, and analyzing the social mechanisms in place that exacerbate or mitigate a population’s sensitivity to hazard events. In keeping with recent trends in research relating to disaster risk, the paper focuses on the social dimension of vulnerability and the contribution of social structures and relationships in building community resilience. Institutional frameworks and policies in particular determine the quantity and quality of resources and services available to people that contribute to resilience over time. The hazard-risk-location-model (HRLM) is proposed that is based on re-specifying disaster risk in terms of exposure and coping ability to capture the focus on social vulnerability and resilience. The framework of the HRLM incorporates the following components: (1) linkages within existing social capital; (2) spatial variation in social and institutional frameworks; (3) positive and negative feedbacks; and (4) characteristics of the hazard event. The model contributes to the range of place-based assessments designed to address the human-environmental impacts of hazards and disasters.     

Uptake and biological effects of synthetic glucocorticoids in common carp (Cyprinus carpio)

Uptake and biological effects of synthetic glucocorticoids (GCs) were analyzed using common carp (Cyprinus carpio). Fish were exposed to clobetasol propionate (CP) or clobetasone butyrate (CB) individually or in mixture at 1 μg L⁻¹ for 21 days. Bioconcentration factor (BCF) of CB was calculated as 100, and BCF of CP was less than 16. No effects were found in fish erythrocyte and leukocyte numbers and serum glucose levels after exposure to the selected GCs. On the other hand, serum concentrations of free amino acids significantly increased in GC-exposed groups. Thus, exposures to synthetic GCs at relatively low concentrations seemed to cause enhancement of protein degradation and subsequent increase of serum free amino acids without a corresponding increase in serum glucose levels, an effect which might be related to partial induction of gluconeogenesis by GC.     

A review of climate geoengineering proposals

Climate geoengineering proposals seek to rectify the current radiative imbalance via either (1) reducing incoming solar radiation (solar radiation management) or (2) removing CO₂ from the atmosphere and transferring it to long-lived reservoirs (carbon dioxide removal). For each option, we discuss its effectiveness and potential side effects, also considering lifetime of effect, development and deployment timescale, reversibility, and failure risks. We present a detailed review that builds on earlier work by including the most recent literature, and is more extensive than previous comparative frameworks. Solar radiation management propsals are most effective but short-lived, whilst carbon dioxide removal measures gain effectiveness the longer they are pursued. Solar radiation management could restore the global radiative balance, but must be maintained to avoid abrupt warming, meanwhile ocean acidification and residual regional climate changes would still occur. Carbon dioxide removal involves less risk, and offers a way to return to a pre-industrial CO₂ level and climate on a millennial timescale, but is potentially limited by the CO₂ storage capacity of geological reservoirs. Geoengineering could complement mitigation, but it is not an alternative to it. We expand on the possible combinations of mitigation, carbon dioxide removal and solar radiation management that might be used to avoid dangerous climate change.