Concerning the occurrence of water in the planetary bodies

The study of the cosmic chemical abundance of the elements suggests that water (which is a combination of the first and second most abundant chemically active elements) is likely to be the most abundant chemical compound in the solar system.It is found that water indeed appears to be a common constituent of planetary bodies even though its presence is not always directly detectable. The amount involved, and the form it takes, varies from one object to another. The Earth has surface liquid water and crustal hydrate materials and only Mars of the terrestrial planets is also likely to have non-atmospheric water and that in frozen form near the surface. The mantles of the icy satellites, and particularly those of Jupiter and Saturn, are the most extended locations of water in the solar system although Uranus and Neptune are likely to have substantial mid-mantle internal water components. Only Mercury and Moon appear to be devoid of water. The smaller bodies such as comets are excluded from the discussion even though they are now known to be composed largely of water-ice.     

Genesis of lavas of the Taupo Volcanic Zone, North Island, New Zealand

The Taupo Volcanic Zone forms part of the Taupo-Hikurangi subduction system, and comprises five volcanic centres: Tongariro, Taupo, Maroa, Okataina and Rotorua. Tongariro Volcanic Centre is formed almost entirely of andesite while the other four centres contain predominantly rhyolitic volcanics and later fissure eruptions of high-Al basalt. Estimated total volume of each lava type are as follows: 2 km³ of high-Al basalt (< 0.1%); 260 km³ of andesite (< 2.5%); 5 km³ of dacite (< 0.1%); > 10,000 km³ of rhyolite and ignimbrite (> 97.4%).The location of the andesites and vent alignments suggest a source from a subduction zone underlying the area. However, the lavas differ chemically from island-arc andesites such as those of Tonga; in particular by having higher contents of the alkali elements, light REE and Sr and Pb isotopes. This suggests some crustal contamination, and it is considered that this may occur beneath the wide accretionary prism of the subduction system. Amphibolite of the subduction zone will break down between 80 and 100 km and a partial melt will rise. A multi-stage process of magma genesis is then likely to occur. High-Al basalts are thought to be derived from partial melting of a garnet-free peridotite near the top of the mantle wedge overlying the subduction zone, locations of the vents controlled largely by faults within the crust. Rhyolites and ignimbrites were probably derived from partial melting of Mesozoic greywacke and argillite under the Taupo Volcanic Zone. Initial partial melting may have been due to hydration of the base of the crust; the “water” having come from dehydration of the downgoing slab. The partial melts would rise to form granodiorite plutons and final release of the magma to form rhyolites and ignimbrites was allowed because of extension within the Taupo graben.Dacites of the Bay of Plenty probably resulted from mixing of andesitic magma with small amounts of rhyolitic magma, but those on the eastern side of the Rotorua-Taupo area were more likely formed by a higher degree of partial melting of the Mesozoic greywacke-argillite basement. This may be due to intrusion of andesite magma on this side of the Taupo volcanic zone.     

The Canadian Fourth Generation Atmospheric Global Climate Model (CanAM4). Part I: Representation of Physical Processes

The Canadian Centre for Climate Modelling and Analysis (CCCma) has developed the fourth generation of the Canadian Atmospheric Global Climate Model (CanAM4). The new model includes substantially modified physical parameterizations compared to its predecessor. In particular, the treatment of clouds, cloud radiative effects, and precipitation has been modified. Aerosol direct and indirect effects are calculated based on a bulk aerosol scheme. Simulation results for present-day global climate are analyzed, with a focus on cloud radiative effects and precipitation. Good overall agreement is found between climatological mean short- and longwave cloud radiative effects and observations from the Clouds and Earth's Radiant Energy System (CERES) experiment. An analysis of the responses of cloud radiative effects to variations in climate will be presented in a companion paper.

[Traduit par la rédaction] Le Centre canadien de la modélisation et de l'analyse climatique (CCmaC) a mis au point la quatrième génération du modèle canadien de circulation générale de l'atmosphère (CanAM4). Le nouveau modèle comprend des paramétrisations physiques passablement modifiées comparativement à son prédécesseur. En particulier, le traitement des nuages, des effets radiatifs des nuages et des précipitations a été modifié. Les effets directs et indirects des aérosols sont calculés à l'aide d'un schéma d'aérosols en bloc. Nous analysons des résultats de simulation pour le climat général du jour présent en mettant l'accent sur les effets radiatifs des nuages et les précipitations. Nous trouvons un bon accord général entre la moyenne climatologique des effets radiatifs des nuages pour les courtes et les grandes longueurs d'onde et les observations de l'expérience CERES (Clouds and Earth's Radiant Energy System). Une analyse de la réponse des effets radiatifs des nuages aux variations du climat sera présentée dans un article connexe.     

Corrosion of metal roof materials related to volcanic ash interactions

Metal roofing material is commonly used for residential and industrial roofs in volcanically active areas. Increased corrosion of metal roofing from chemically reactive volcanic ash following ash deposition post-eruption is a major concern due to decreasing the function and stability of roofs. Currently, assessment of ash-induced corrosion is anecdotal, and quantitative data are lacking. Here, we systematically evaluate the corrosive effects of volcanic ash, specifically ash leachates, on a variety of metal roofing materials (i.e. weathered steel, zinc, galvanized steel, and Colorsteel©) utilizing weathering chamber experiments and direct acid treatments. Weathering chamber tests were carried out for up to 30 days, and visual, chemical, and surface analyses did not definitively identify significant corrosion in any of the test roofing metal samples. Direct concentrated acid treatments with hydrochloric (HCl), sulphuric (H₂SO₄), and hydrofluoric (HF) acids demonstrate that roofing materials are chemically resilient. Our experimental results suggest that ash-leachate-related corrosion is a longer-term process (>1 month), potentially related to a multitude of factors including increased ash leachate concentrations, the dissolution of the glass matrix of the ash, moisture retention at the ash-surface boundary, and potential reactions involving photo-oxidation. Overall, corrosion is not a simple process related to the short-term release of acid and/or salt leachates from the ash surface, but a product of dynamic interactions involving ash and water at the surface of metal roofing material for extended periods.     

Systematic Errors Induced by the Elliptical Power-law model in Galaxy-Galaxy Strong Lens Modeling

The elliptical power-law model of the mass in a galaxy is widely used in strong gravitational lensing analyses.However,the distribution of mass in real galaxies...