Introduction

Abstract

This Special Issue was originally conceived as an opportunity to publish together papers presented at or submitted for the symposium “Models of the Geodynamo and Core-Mantle Coupling” as part of the International Association of Geomagnetism and Aeronomy (IAGA) 7th Scientific Assembly held in Buenos Aires during August 1993. This Symposium (1 .l) was convened by Michael Proctor and Ivan Cupal. While a large proportion of the papers fall into this category, in the interests of a more harmonious whole it has been decided to adjoin some others. These latter, while not directly connected with the meeting, nonetheless address problems in the same area of geomagnetism, and their presence will, it is hoped, enhance the impact of the Issue.     

Materials embodied in international trade – Global material extraction and consumption between 1995 and 2005

Production and consumption activities in industrialized countries are increasingly dependent on material and energy resources from other world regions and imply significant economic and environmental consequences in other regions around the world. The substitution of domestic material extraction and processing through imports is also shifting environmental burden abroad and thus extends the responsibility for environmental impacts as well as social consequences from the national to the global level. Based on the results of the Global Resource Accounting Model, this paper presents the first trade balances and consumption indicators for embodied materials in a time series from 1995 to 2005. The model includes 53 countries and two world regions. It is based on the 2009 edition of the input–output tables and bilateral trade data published by the Organisation for Economic Co-operation and Development (OECD) and is extended by physical data on global material extraction. The results quantify the global shift of embodied material resources from developing and emerging countries to the industrialized world. In addition to the level of industrialization and wealth, population density is identified as an important factor for the formation of physical trade patterns. Exports of embodied materials of less densely populated countries tend to surpass their imports, and vice versa. We also provide a quantitative comparison between conventionally applied indicators on material consumption based on direct material flows and indicators including embodied material flows. We show that the difference between those two indicators can be as much as 200%, calling for an adjustment of conventional national material flow indicators. Multi-regional input–output models prove to be a useful methodological approach to derive globally consistent and comprehensive data on material embodiments of trade and consumption.     

A review of: “The earth's core”

Abstract

by J. A. Jacobs, 1975, Academic Press, London, New York, San Francisco, U.S.A., viii + 253 pages.     

The Sequence-of-Bifurcations Approach towards Understanding Turbulent Fluid Flow

The sequence-of-bifurcations approach for the analysis of transitionsfrom simple to complex forms of fluid flow is described.Formulated for fluid systemswith external conditions that are homogeneous in two spatial dimensionsand in time,this approach determines bifurcations through theirsymmetry breaking properties.Solutions that are periodic in the homogeneous dimensionsand in time are generatedin this way. While the secondary solution induced by theinstability of the basichomogeneous state generically assumes the form of rolls orstripes, higher bifurcationsintroduce solutions exhibiting structures specific for thephysical system underconsideration. These structures often persist in the formof coherent structures inthe turbulent state of the system. Examples from the caseof thermal convection in alayer heated from below are used to illustrate thesequence-of-bifurcations approach.     

Convection-driven zonal flows in the major planets

The major planets produce heat flux from their interiors that is comparable to the radiative flux they receive from the sun. The dynamics of convection flows carrying the heat flux are discussed, and the dominating effect of the Coriolis force is demonstrated. The characteristic high-velocity jets in the atmospheres of Jupiter and Saturn can be explained on the basis of Reynolds stresses generated by the fluctuating convective motions. A simple annulus model, which elucidates the more complex mathematical analysis of the spherical case given in an earlier paper (Busse, 1983), is considered in detail. Various aspects of the observational evidence are discussed in relation to the model.     

The use of maximum entropy to increase the informational content of hydrological networks by additional gauges

ABSTRACT

The optimization and extension of existing gauging networks are a challenging task, which can be done under consideration of many different aspects. One possibility is to maximize the obtained information on regional hydrological characteristics by new gauges compared to existing ones. For this, information theory approaches are most suitable. Here, the principle of maximum entropy is applied to calculate the probability of non-similarity of catchments to determine locations of new gauges according to the catchment characteristics that are most relevant for the hydrological conditions. The realization in an interactive application, provided online, makes use easy for practitioners and scientists. Goodness-of-fit measures are applied to investigate the explanatory power of the model and the contribution of each characteristic to the model, which gives information on the most influential properties of the catchment. The relevance of the proposed approach is proven by comparing hydrological signatures between similar and non-similar catchment.     

Desalinization of running waters: II. Benthic diatom communities: A comparative field study on responses to decreasing salinities

Desalinization effects on benthic diatom communities were investigated in two adjacent streams in Northern Thuringia, the creek Urbach and the river Helbe. Salt-saturated stockpile effluents had been introduced into the Urbach until 1996, resulting in fluctuating chloride concentrations with maximum values up to 25.4 g · 1⁻¹ (Helbe: max. 3.7 g · 1⁻¹).

The diatom vegetation and hydrographical and chemical data of an Urbach site were compared to those of a sampling site further downstream. Monthly sampling in 1996 started at the end of salt influx in January. Reference samples from the years 1995, 1986 and 1963 were evaluated along with the 1996 samples.

After termination of the introduction of salt-loaded effluents, relative abundances of brackish water species greatly decreased within three months. The Halobion Index (Ziemann 1982), reflecting osmotic and ion composition effects on diatoms, decreased until May 1996, then stabilized. In summer 1996, several diatoms had a mass development, showing that salinization impacts had previously overruled effects of other environmental variables.