On the asteroid belt's orbital and size distribution

For absolute magnitudes greater than the current completeness limit of H-magnitude ∼15 the main asteroid belt's size distribution is imperfectly known. We have acquired good-quality orbital and absolute H-magnitude determinations for a sample of small main-belt asteroids in order to study the orbital and size distribution beyond H=15, down to sub-kilometer sizes (H>18). Based on six observing nights over a 11-night baseline we have detected, measured photometry for, and linked observations of 1087 asteroids which have one-week time baselines or more. The linkages allow the computation of full heliocentric orbits (as opposed to statistical distances determined by some past surveys). Judged by known asteroids in the field the typical uncertainty in the (a/e/i) orbital elements is less than 0.03 AU/0.03/0.5°. The distances to the objects are sufficiently well known that photometric uncertainties (of 0.3 magnitudes or better) dominate the error budget of their derived H-magnitudes. The detected asteroids range from HR=12-22 and provide a set of objects down to sizes below 1 km in diameter. We find an on-sky surface density of 210 asteroids per square degree in the ecliptic with opposition magnitudes brighter than mR=23, with the cumulative number of asteroids increasing by a factor of 10^0.27/mag from mR=18 down to the mR?23.5 limit of our survey. In terms of absolute H magnitudes, we find that beyond H=15 the belt exhibits a constant power-law slope with the number increasing proportional to ¹⁰0.30H from H?15 to 18, after which incompleteness begins in the survey. Examining only the subset of detections inside 2.5 AU, we find weak evidence for a mildly shallower slope for H=15-19.5. We provide the information necessary such that anyone wishing to model the main asteroid belt can compare a detailed model to our detected sample.     

Zur Kenntnis der präkambrischen,schichtgebundenen Molybdänitvorkommen in Südnorwegen

The southern Norwegian molybdenum deposits have hitherto been looked upon as typical examples of deposits of pneumatolytic — catathermal origin formed by emanations from intrusive granites. It is now demonstrated that all these deposits are to be found stratabound in a series of grey gneisses. They are accompanied by varying amounts of graphite and apatite of biogenetic origin and all of them show the same sulphide and oxide ore mineral paragenesis. It is concluded that the concentration and precipitation of metals took place in marine environments. Both the ores and their host rocks later underwent the same highmetamorphic processes.     

100 years Jura décollement hypothesis: how it affects Steinmann’s (1892) “Schwarzwaldlinie”

Steinmann, then professor of geology at Freiburg (Germany), more than a 100 years ago wondered about the southern end of the extensional Rhinegraben and proposed that elements of the graben penetrated the contractional Jura. In particular, he recognized the "Schwarzwaldlinie” in the southern prolongation of the eastern border of the southern Rhinegraben, a line-up of topographic as well as structural irregularities. He conjectured that it was caused by normal faults of the Rhinegraben system. Subsequently—100 years ago—Buxtorf (1907) proposed the hypothesis, that the Jura was a thin-skinned nappe sheared off on Triassic evaporites. In the autochthonous basement underneath the wrinkled skin, the ``Schwarzwald line” is difficult to define. It probably consists of a gentle flexure punctuated by faults that approximately coincides with Steinmann’s original projection, although he sought to identify its constituent faults in the badly deformed allochthonous skin. Current data place the thin-skin elements of the Schwarzwald line in a more westerly, allochthonous position where most of them were reactivated into sinistrally transpressional structures.     

Towards an operational aqueous phase chemistry mechanism for regional chemistry-transport models: CAPRAM-RED and its application to the COSMO-MUSCAT model

Mechanism reductions of the detailed aqueous phase chemistry mechanism CAPRAM 3.0i are performed. Manual methods and automatic techniques are both applied in order to provide a less computationally intensive mechanism which is operational in regional chemistry transport models (CTMs). The finally reduced mechanism contains less than 200 reactions (4 times smaller than the detailed CAPRAM 3.0i) and describes the main characteristics of inorganic and organic aqueous phase processes occurring in tropospheric warm clouds. Most of the chemical reduction potential is realized in the CAPRAM 3.0i organic chemistry. The number of aqueous phase species decreases from 380 in the full mechanism to 130 in the final reduced version. The calculated percentage deviations between the full and reduced mechanism are on average below 5% for the most important organic and inorganic target compounds such as oxidants, inorganic and organic acids, carbonyls and alcohols. Comparisons of the required CPU times between the full and reduced mechanisms show reductions of approximately 40%. 2-D test simulations with the CTM MUSCAT were performed using prescribed meteorological conditions in order to examine the applicability of the reduced mechanism at regional scale. Simulations with the reduced CAPRAM 3.0i mechanism and a much less complex mechanism with only limited inorganic chemistry (INORG) were compared to evaluate the effects of more detailed chemistry. The model results show large differences in the level of oxidants and the inorganic and organic mass processing. Prospectively, the reduced mechanism represents the basis for studying aerosol cloud processing effects at regional scale with future CTMs and will allow more adequate interpretation of field data.     

Exploring pathways for sustainable water management in river deltas in a changing environment

Exploring adaptation pathways into an uncertain future can support decisionmaking in achieving sustainable water management in a changing environment. Our objective is to develop and test a method to identify such pathways by including dynamics from natural variability and the interaction between the water system and society. Present planning studies on long-term water management often use a few plausible futures for one or two projection years, ignoring the dynamic aspect of adaptation through the interaction between the water system and society. Our approach is to explore pathways using multiple realisations of transient scenarios with an Integrated Assessment Meta Model (IAMM). This paper presents the first application of the method using a hypothetical case study. The case study shows how to explore and evaluate adaptation pathways. With the pathways it is possible to identify opportunities, threats, timing and sequence of policy options, which can be used by policymakers to develop water management roadmaps into the future. By including the dynamics between the water system and society, the influence of uncertainties in both systems becomes clearer. The results show, among others, that climate variability rather than climate change appears to be important for taking decisions in water management.     

Population Belongs on the Johannesburg Agenda

The forthcoming World Summit on Sustainable Development (WSSD) in Johannesburg (August 26-September 4, 2002) has been set by the United Nations to consider strategies toward sustainable development in all its dimensions. Hence, its mandate is broader than that of the Rio 1992 United Nations Conference on Environment and Development (UNCED). Population issues have so far been discussed in a separate series of World Population Conferences (Bucharest 1974, Mexico City 1984, Cairo 1994). With no new World Population Conference scheduled for 2004 and Johannesburg having a mandate that is stated to explicitly include social and economic aspects, population as a key component of sustainable development should figure prominently on the Johannesburg agenda. Yet, after the third of four preparatory meetings for Johannesburg (which ended in New York on April 5th), consideration of population is completely absent. The reasons for this are not entirely clear. We assume that they have to do with the fear of entering into political controversies over abortion. We are concerned that, despite its broader mandate, in most countries inputs to Johannesburg are being prepared mainly by environment ministries who have little experience in dealing with population questions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Vegetation and Climate Reconstruction of the Planalto in Rio Grande do Sul, South Brazil (Late Glacial and Holocene)

1IntroductionThe ecosystem of Araucaria-Forest is one of the most important plant-associations in South Brazil. Today,however,the spreading area is a fraction of its natural size,originally spread over 200 km. It spanned from 18°to 30°of southern lati-t…     

An integrated model for the assessment of the greenhouse effect: The Dutch approach

This paper describes a simulation policy model of the combined greenhouse effects of trace gases. With this model, the Integrated Model for the Assessment of the Greenhouse Effect (IMAGE) scenarios for the future impact of the greenhouse effect can be made, based on different assumptions for technological and socio-economic developments. The contribution of each trace gas can be estimated separately.Basically the model, consisting of a number of coupled modules, gives policy makers a concise overview of the problem and enables them to evaluate the impact of different strategies. Because the model covers the complete cause-effect relationship it can be utilized to derive allowable emission rates for the different trace gases from set effect related targets. Regular demonstration sessions with the simulation model have proven the importance of such science based integrated models for policy development.Four different scenarios are worked out for the most important trace gases (CO₂, CH₄, N₂O, CFC-11 and CFC-12). One of these scenarios can be regarded as a growth scenario unrestricted by environmental concerns. The others are based on different strategic policies. After the simulation of future trace gas concentrations global equilibrium temperature increases are computed. Finally the sea level rise, the most threatening effect of the greenhouse problem for the Netherlands, is estimated.Simulation results so far emphasize the importance of trace gases other than CO₂. The Montreal Protocol on reduction of CFC is found to stabilize the relative contribution of these substances to the greenhouse effect.