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21.
High spatial resolution infrared and visible data obtained by the Voyager 1 spacecraft have been analyzed simultaneously to infer properties of the deep cloud structure of the Jovian troposphere in the 1- to 4-bar pressure range. Influence of the ammonia upper cloud layer, in the 5μm Jovian window, has been investigated through a cloud model derived from far ir Voyager IRIS measurements. The attenuation, computed with an anisotropic scattering formulation, is too weak to explain 5-μm measurements and provides evidence for existence of a cloud structure at deeper levels. The main conclusions derived from the present analysis are summarized below: (1) the deep cloud structure appears to be vertically associated with the NH3 upper layer; (2) the ammonia cloud is mainly responsible for the visible appearance of the Jovian equatorial region; (3) the deep cloud structure exhibits a grey opacity in the 5-μm window; (4) coldest 5-μm spectra can be interpreted by the existence of a thick cloud layer located at levels in the 180–195°K temperature range. Implications of these results are discussed in conjunction with predictions of dynamical and thermochemical models. NH4SH is shown to be a likely candidate for the main deep cloud constituent. An even deeper thick H2O cloud may be present too, but should not be responsible for the observed spread in 5-μm brightness temperatures. 相似文献
22.
Frankie Thielen Uwe Weibel Jürgen Hirt Marcel Münderle Michael Marten Horst Taraschewski Bernd Sures 《Limnologica》2008,38(1):76-85
The fish fauna in the northern part of the upper river Rhine close to the city of Karlsruhe (Germany) was analyzed by collecting fish from the cooling-water intake of a power plant (impingement method) between 1989 and 2001. With this method a total of 36 fish species were recorded. The results were compared between the years as well as with other studies on the fish fauna in this area. Particularly with regard to the physical structure of the river bed and banks, the pre-technical situation of the river Rhine has not been restored. However, the number of fish species has been augmented since the 1970s mainly due to improvements in the water quality and almost all autochthonous fish species are present again. Altogether only three introduced fish species (Sander lucioperca L., Lepomis gibbosus L., and Carassius auratus gibelio were found in this study. Among the long-distance migrating species three freshwater spawners (Lampetra fluviatilis, Petromyzon marinus and Salmo trutta trutta) were detected in addition to the catadromous eel. The eudominant fish species varied between years, i.e. the European eel, Anguilla anguilla, was the eudominant species 1989, whereas this species occurred in much lower numbers during the subsequent sampling campaigns. This clearly indicates that the high dominance of eels is mainly caused by stocking activities in the upper Rhine. In the following years roach, Rutilus rutilus was the eudominant fish species. Overall a positive development of the fish fauna in the upper Rhine over the last 15 years could be observed in terms of fish populations as well as in terms of species richness. 相似文献
23.
Fluid-assisted granulite metamorphism: A continental journey 总被引：10，自引：0，他引：10
Jacques L.R. TouretAuthor VitaeJan Marten HuizengaAuthor Vitae 《Gondwana Research》2012,21(1):224-235
Lower crustal granulites, which constitute the base of all continents, belong to two series: high-pressure granulites generated by crustal thickening (subduction) and (ultra)high-temperature granulites associated with crustal extension. Fluid inclusions and metasomatic features indicate that the latter were metamorphosed in the presence of low-water activity fluids (high-density CO2 and brines), which have invaded the lower crust at peak metamorphic conditions (fluid-assisted granulite metamorphism). High-pressure and (ultra)high-temperature granulites commonly occur along elongated paired belts. They were formed, from the early Proterozoic onwards, during a small number of active periods lasting a few hundreds of m.y. These periods were separated from each other by longer periods of stability. Each period ended with the formation of a supercontinent whose amalgamation coincided with low- to medium pressure (ultra)high-temperature granulite metamorphism, immediately before continental break-up. It is proposed that large quantities of mantle-derived CO2 stored in the lower crust at the final stage of supercontinent amalgamation, are released into the hydro- and atmosphere during breakup of the supercontinent. Fluid-assisted granulite metamorphism, therefore, appears to be an important mechanism for transferring deep mantle fluids towards the Earth's surface. Possible consequences were, for example, the sudden end of Proterozoic glaciations, as well as the post-Cambrian explosion of life. 相似文献
24.
Alex L. Marten Elizabeth A. Kopits Charles W. Griffiths Stephen C. Newbold Ann Wolverton 《Climate Policy》2013,13(5):678-679
The light bulb ban introduced by the EU is used as an example to illustrate how to assess the climate impact of a policy that overlaps with a cap-and-trade scheme. The European Commission estimates that by 2020 the reduction in GHG emissions induced by banning incandescent light bulbs will reach 15 million tons annually. The number is a conservative estimate for the reduction in emissions from lighting if the total residential stock of incandescent light bulbs in 2008 is replaced by more efficient lighting sources. However, it ignores that use-phase and some non-use-phase emissions are covered by the EU Emission Trading Scheme (EU ETS). This drastically reduces the amount of GHG emissions saved.Policy relevanceSeveral policies such as the EU-wide ban on incandescent light bulbs, energy efficiency mandates and support mechanisms for renewable energy overlap with the EU ETS. While there are typically several justifications for these policies, a chief reason is the reduction of GHG emissions. However, given that the aggregate emissions of the industries covered are fixed by the EU ETS, the climate change mitigation aspect of these policies is not obvious. Using the light bulb ban as an example, this article illustrates how a focus on non-EU ETS emissions changes the assessment of an intervention in terms of GHG reductions. 相似文献
25.
Although existing economic research is informative with regard to the importance of including potential ‘catastrophic’ climate change impacts in the analysis of GHG mitigation benefits, the generic and abstract form of the ‘catastrophe’ implemented has led to a lack of specific policy implications. This article provides an important starting point for a discussion of how to improve economic modelling of potential large-scale impacts of climate change. It considers how the term ‘abrupt climate change’ has been used in the scientific literature to describe changes in the climate system and carefully reviews the characteristics of the events that have been discussed in this context. The findings are compared to the way in which the economic literature has modelled potential economic and human welfare impacts of these ‘catastrophic’ events. In general, the economics literature is found to have modelled such impacts in a uniform way that fails to account for differences in relevant end points and timescales. The result is policy recommendations based on events that do not resemble those of concern. Better treatment of these events in integrated assessment modelling would help ensure that future research efforts can serve as meaningful policy input. 相似文献
26.
Temporal variability of diverse mountain permafrost slope movements derived from multi-year daily GPS data,Mattertal, Switzerland 总被引：1，自引：0，他引：1
In this study, high resolution surface measurements of diverse slope movements are compared to environmental factors such as ground surface temperature (GST) and snow cover, in order to reveal and compare velocity fluctuations caused by changing environmental conditions. The data cover 2 years (2011–2013) of Global Positioning System (GPS) and GST measurements at 18 locations on various slope movement types within an alpine study site in permafrost (Mattertal, Switzerland). Velocities have been estimated based on accurate daily GPS solutions. The mean annual velocities (MAV) observed at all GPS stations varied between 0.006 and 6.3 ma?1. MAV were higher in the period 2013 compared to 2012 at all stations. The acceleration in 2013 was accompanied by a longer duration of the snow cover and zero curtain and slightly lower GST. The amplitude (0–600 %) and the timing of the intra-annual variability were generally similar in both periods. At most stations, an annual cycle in the movement signal was observed, with a phase lag of 1–4 months to GST. Maximum velocity typically occurred in late summer and autumn, and minimum velocity in late winter and beginning of spring. The onset of acceleration always started in spring during the snowmelt period. At two stations located on steep rock glacier tongues, overprinted on the annual cycle, short-term peaks of velocity increase, occurred during the snowmelt period, indicating a strong influence of meltwater. 相似文献
27.
Vittorio Scheffer 《Pure and Applied Geophysics》1941,3(1):12-13
Riassunto Sono posti a confronto i risultati del rilevamento gravimetrico della zona di Fontevivo (Parma) eseguiti prima con bilancia di torsione e successivamente con gravimetro (tipc Humble-Truman); ottenendosi un buon accordo fra i due metodi.
Zusammenfassung Vergleich der Ergebnisse der gravimetrischen Aufnahme von der Umgebung von Fontevivo (Parma), zuerst mit der Drehwaage durchgeführt, nachher mit einem Gravimeter nach Humble-Truman; die Übereinstimmung der Ergebnisse ist befriedigend.
Résumé Comparaison des résultats du levé gravimétrique de la zone de Fontevivo (Parme) effectué d'abord avec la balance de torsion, ensuite avec un gravimètre type Humble-Truman; bonne concordance entre les deux méthodes.相似文献
28.
Jens Blotevogel Charles Pijls Bert Scheffer Jean-Paul de Waele Amy Lee Reggy van Poecke Nicolaas van Belzen Wim Staal 《Ground Water Monitoring & Remediation》2019,39(1):36-42
Electrochemical treatment is a promising emerging technology in which direct current is applied to drive the degradation of aqueous contaminants. Several bench-scale studies have demonstrated the capability of electrochemical oxidation to fully mineralize refractory organics such as pesticides and perfluorinated compounds. However, insights into large-scale design and field performance are critically lacking. Here, we designed six pilot-scale reactors and tested their performance and efficiency for the treatment of groundwater contaminated with 1,4-dioxane (1,4-DX) at concentrations exceeding 1000 mg/L. Anode surface area-normalized degradation rates increased with increasing potential applied, while the process was more energy-efficient per mass unit removed at low potentials. While not all 1,4-DX was completely mineralized, the detected ring-opening intermediates are known to be readily biodegradable. Analyses of potential by-products from chloride oxidation revealed the generation of chloromethanes and perchlorate at low mg/L concentrations. Towards the end of the 8.5-month pilot test, decreasing currents and degradation rates indicated progressing passivation of the electrodes, likely due to cathodic carbonate precipitation and/or poisoning by the uniquely high organic carbon load of this source zone groundwater. The findings of our study demonstrate that electrochemical groundwater remediation is a capable approach for the treatment of persistent organic pollutants. Our pilot-scale test provides practitioners with a basis for evaluating its efficiency under site-specific conditions and collecting critical performance metrics for technology scale-up. 相似文献
29.
Amelia J. Couldrey Thomas Benson Michiel A.F. Knaapen Kerry V. Marten Richard J.S. Whitehouse 《地球表面变化过程与地形》2020,45(12):2884-2896
As the number of manmade structures installed on the seafloor is increasing rapidly, we seek to understand the impact of these immobile obstacles on marine geomorphological processes, such as the evolution of bedforms. A 5.8 m diameter monopile foundation was installed at the case study offshore windfarm approximately 30 m ahead of an approaching barchan (crescent-shaped) dune. The impact of the monopile on the dune's evolution was analysed using six multibeam bathymetry surveys spanning 20 years. To substantiate this analysis, coupled three-dimensional numerical modelling of flows and sediment was conducted in which the scour inducing bed shear stresses were calculated from the modelled turbulent kinetic energy. Following the installation of the monopile, the mid-section of the dune accelerated and stretched in the direction of the wake of the monopile. Four years after the monopile's installation the rest of the dune had caught up, flattening out the slip face within half the dune's length downstream of the monopile. Due to the modified flow field, the dune was scoured deeply at the base of the monopile to a depth of 6.8 m (supported by the model results that predicted a scour depth exceeding 2 m over a period of just a few days). The surveyed volume of material scoured amounted to 8% of the total dune volume. Whilst the process of scouring occurs at a timescale of days to weeks, the dune migrated on average by 25 m/yr. The difference in the timescale of the two processes allowed the scouring to occur through the full thickness of the dune. The scoured dune profile recovered rapidly once the dune migrated downstream of the monopile. This article demonstrates how large geomorphological features can intercept and migrate past a monopile foundation without long-lasting impacts on the integrity of the feature or the foundation. © 2020 John Wiley & Sons, Ltd. 相似文献
30.
Terrain stability mapping on British Columbia forest lands: an historical perspective 总被引：1，自引：0，他引：1
Land management associated with forest practices in British Columbia (BC) over the last three decades has led to the development
of terrain stability hazard mapping. Terrain stability mapping (TSM) in BC originated in the early 1970s, when forest harvesting
was progressing from valley bottoms onto steep, unstable terrain, which led to an increase in harvesting- and road-related
landslides. Since then TSM methods have been evolved. Beginning in the early 1970s, terrain hazards were incorporated into
the forest inventory classification system to delineate environmentally sensitive areas for land-use planning. By 1974, operational
terrain stability maps were introduced by the MacMillan Bloedel forest company on the Queen Charlotte Islands. In the 1980s,
this method was adopted by other forest companies and government agencies along the BC coast and then extended to the BC interior
in the 1990s. The system was refined over time, based on new knowledge and on the introduction of mapping standards, including
standards for capture and presentation of digital maps. In 1995, reconnaissance terrain stability mapping and detailed terrain
stability mapping were formalized with three and five hazard classes, respectively. More recently, qualitative and semi-quantitative
approaches to predict landslide occurrence based on terrain and landslide inventories have been incorporated into the techniques
for TSM. 相似文献