An embedded mixed-layer-ocean circulation model

The rationale and numerical technique of embedding an oceanic bulk mixed-layer model with a multi-level primitive equation model is presented. In addition to the usual prognostic variables that exist in a multi-level primitive equation model, the embedded model predicts the depth of the well-mixed layer as well as the jumps in temperature and velocity that occur at the base of that layer. The depth of the mixed layer need not coincide with any of the fixed-model levels used in the primitive equations calculations.In addition to advective changes, the mixed layer can deepen by entrainment and it can reform at a shallower depth in the absence of entrainment. When the mixed layer reforms at a shallower depth, the vertical profile of temperature below the new, shallower mixed layer is adjusted to fit the fixed-level structure used in the primitive equations calculations using a method which conserves heat, momentum and potential energy. Finally, a dynamic stability condition, which includes a consideration of both the vertical current shear and the vertical temperature gradient, is introduced in place of the traditional ‘convective adjustment’.A two-dimensional version of the model is used to test the embedded model formulations and to study the response of the ocean to a stationary axisymmetric hurricane. The model results indicate a strong interdependence between vertical turbulent mixing and advection of heat.     

Stereoscopic determination of the three-dimensional geometry of coronal magnetic loops

The three-dimensional shape of coronal magnetic loops is restored from extreme ultraviolet (XUV) images of the Sun (Skylab mission 3, 1973) by using the perspective effect due to the solar rotation. An original method is developed which only depends on the assumption that the magnetic structures under consideration are (at least geometrically) stable within the time interval used for restoration. Large scale loops interconnecting different active regions are studied by applying this method. They are found to lie approximately in planes inclined from the local vertical. Generally these loops are asymmetric, i.e. their apices are shifted toward one of the footpoints. This tendency is also confirmed by the computation of coronal magnetic fields based on the photospheric magnetic data.On leave from Observatoire de Paris-Meudon, 91190 Meudon, France.     

Approaching a dynamic view on the availability of mineral resources: What we may learn from the case of phosphorus?

This paper elaborates in what way a dynamic perspective on reserves, resources and geopotential is necessary to provide robust estimates on resource availability. We introduce concepts of essentiality, criticality and economic scarcity and discuss for the case of phosphorus (P) how they are defined and may be measured. The case of P is considered in detail as P an essential element for global food security with a highly dissipative use and is geographically unevenly distributed across the globe. We distinguish and relate the complementarity between physical and economic scarcity and discuss limits and potential of static indicators such as static lifetime, Hubbert curve applications, and the Herfindahl–Hirschman-Index of P for predicting future availability of these resources. We reveal that these static indicators are – in general – not valid approaches to predict physical scarcity of resources. Geological data show that though the P reserves have not been systematically and completely assessed on a global scale, the static lifetime of P is high. When acknowledging socio-economic and technological dynamics, and available geological facts, statements predicting physical scarcity or a peak in P production within a few decades are unlikely to be accurate or valid. We elaborate that some simplified indicators such as static lifetime or the Hubbert curve based prediction of peaks may serve as screening indicators preceding early warning research, which may induce increased mining activities, technology innovation or other actions. However, in general, these simplified indicators are not valid approaches to predict physical scarcity of resources. Although one day there may be a supply-driven P production peak, demand-driven production plateaus and multiple peaks are probable in the near future. Given its geopotential, essentiality, and the learning curve of efficient fertilizer use, P is subject to demand-driven market dynamics. Thus, a symmetric decline and unavoidable shortage of P in the next decades are unlikely. This insight does not refute the need to close the anthropogenic P loop. Activities associated with P production and consumption use has a significant pollution potential in part because of the dissipative nature. The paper reveals the necessity to mitigate risks (such as economic scarcity, especially for poor farmers) of both short-term price peaks and longer lasting step-changes in price, e.g. due to knowledge gaps of technological adaptation in energy and water management or other reasons of insufficient supply-demand dynamics management. The complexity of this task necessitates a transdisciplinary approach.     

Institutional design propositions for the governance of adaptation to climate change in the water sector

This paper provides an evidence-based contribution to understanding processes of climate change adaptation in water governance systems in the Netherlands, Australia and South Africa. It builds upon the work of Ostrom on institutional design principles for local common pool resources systems. We argue that for dealing with complexities and uncertainties related to climate change impacts (e.g. increased frequency and intensity of floods or droughts) additional or adjusted institutional design propositions are necessary that facilitate learning processes. This is especially the case for dealing with complex, cross-boundary and large-scale resource systems, such as river basins and delta areas in the Netherlands and South Africa or groundwater systems in Western Australia. In this paper we provide empirical support for a set of eight refined and extended institutional design propositions for the governance of adaptation to climate change in the water sector. Together they capture structural, agency and learning dimensions of the adaptation challenge and they provide a strong initial framework to explore key institutional issues in the governance of adaptation to climate change. These institutional design propositions support a “management as learning” approach to dealing with complexity and uncertainty. They do not specify blueprints, but encourage adaptation tuned to the specific features of local geography, ecology, economies and cultures.     

Morphology and kinematics of the ionised gas in early-type galaxies

We present results of our ongoing study of the morphology and kinematics of the ionised gas in 48 representative nearby elliptical and lenticular galaxies using the SAURON integral-field spectrograph on the 4.2m William Herschel Telescope. Making use of a recently developed technique, emission is detected in 75% of the galaxies. The ionised-gas distributions display varied morphologies, ranging from regular gas disks to filamentary structures. Additionally, the emission-line kinematic maps show, in general, regular motions with smooth variations in kinematic position angle. In most of the galaxies, the ionised-gas kinematics is decoupled from the stellar counterpart, but only some of them present signatures of recent accretion of gaseous material. The presence of dust is very common in our sample and is usually accompanied by gas emission. Our analysis of the [Oiii]/Hβ emission-line ratios, both across the whole sample as well as within the individual galaxies, suggests that there is no unique mechanism triggering the ionisation of the gas.     

A DUAL mission for nuclear astrophysics

DUAL will study the origin and evolution of the elements and explores new frontiers of physics: extreme energies that drive powerful stellar explosions and accelerate particles to macroscopic energies; extreme densities that modify the laws of physics around the most compact objects known; and extreme fields that influence matter in a way that is unknown on Earth. The variability of these extreme objects requires continuous all-sky coverage, while detailed study demands an improvement in sensitivity over previous technologies by at least an order of magnitude. The DUAL payload is composed of an All-Sky Compton Imager (ASCI), and two optical modules, the Laue-Lens Optic (LLO) and the Coded-Mask Optic (CMO). The ASCI serves dual roles simultaneously, both as an optimal focal-plane sensor for deep observations with the optical modules and as a sensitive true all-sky telescope in its own right for all-sky surveys and monitoring. While the optical modules are located on the main satellite, the All-Sky Compton Imager is situated on a deployable structure at a distance of 30?m from the satellite. This configuration not only permits to maintain the less massive payload at the focal distance, it also greatly reduces the spacecraft-induced detector background, and, above all it provides ASCI with a continuous all-sky exposure.     

Applicability of the ACE algorithm for multiple regression in hydrogeology

This paper introduces the alternating conditional expectation (ACE) algorithm of Breiman and Friedman (J Am Stat Assoc 80:580–619, 1985) for estimating the transformations of a response and a set of predictor variables in multiple regression problems in hydrogeology. The proposed nonparametric approach can be applied easily for estimating the optimal transformations of different hydrogeological data to obtain maximum correlation between observed variables. The approach does not require a priori assumptions of a functional form, and the optimal transformations are derived solely based on the data set. The advantages and applicability of this new approach to solve different multiple regression problems in hydrogeology or in Earth Sciences are illustrated by means of theoretical investigations and case studies. It is demonstrated that the ACE method has certain advantages in some fitting problems of hydrogeology over the traditional multiple regression. Based on our knowledge, this is the first application of the ACE algorithm to analyze and interpret groundwater data.     

Characterization and low-cost treatment of an industrial arid soil polluted with lead sulfide in northern Chile

Lead (Pb) dust exposure can have detrimental environmental and human health effects. Improperly enclosed stockpiles of Pb concentrates can cause dust emissions, subsequent pollution of the soil and environmental risk. The aim of this work was to study Pb form, distribution and immobilization (by using eggshell and seashell) in an industrial arid soil near a storage area of Pb mineral concentrates in northern Chile. High amounts of sulfur (S; 9900 mg kg^?1) and Pb (6530 mg kg^?1) were found in the polluted soil. The energy-dispersive X-ray spectroscopy analysis revealed a lead sulfide (PbS: galena). Metallic Pb particles, which were between 41 and 46 µm, were identified in the soil. After eggshell and seashell (20%) were applied, the soil pH increased from 6.0 to 7.84 and 8.07, respectively. In the studied soil, the leaching test showed a 59 mg L^?1 average Pb extractable concentration. After 240 days, extractable Pb by toxicity characteristics leaching procedure decreased to 4.79 mg L^?1 (93.3%) with the application of seashell at 20% compared with a decrease of 33.33 mg L^?1 (53.6%) using eggshell. Pb in the polluted soil was mainly found in the exchangeable fraction (66%), followed by the reducible (24%), residual (7%) and oxidizable (6%) fractions. According to the risk assessment code, the contaminated soil before treatment was classified as very high risk. Adding eggshell (20%) and seashell (20%) decreased the exchangeable fractions to 39 and 35%, respectively. Applying these liming materials achieved Pb immobilization in the soil, but the soil remained in the high environmental risk category. We conclude that the application of seashell waste, resulting from high aquaculture activity, opens an interesting window to the treatment of contaminated arid soils.