Context in Human Geography: A Multilevel Approach to Study Human–Environment Interactions∗

One of the shortcomings of quantitative methods in human geography is an overreliance on models that can only account for the average outcomes of spatial events. Although methodological advancements in the form of multilevel models now allow human geographers to account for average outcomes as well as deviations about average outcomes of spatial events, it is not without question that such models can fully account for the cultural, political, and social contexts that affect human behavior. In this article I argue for the adoption of a multilevel approach to the study of human behavior to address some of the criticisms of quantitative methods in human geography. Using a transportation geography research agenda as an example, I discuss how a multilevel approach can complement qualitative methods. Such mixed research methods offer human geographers the opportunity to identify the appropriate role for quantitative methods and explore how context affects behavior.     

New results regarding the influence of solar activity on the stratospheric-tropospheric exchange

Summary The dependence of stratospheric intrusions on solar events is analyzed on the basis of 8-years' recordings of the concentration of stratospheric radionuclides and the ozone at 3 km altitude, as well as of the atmospheric profile of the ozone concentration and the total ozone.A significant, even though weak influence of solar magnetic sector structure boundary passages of type-/+ can be identified, a seasonal influence, however, is also observed. The strong 50 to 80% increase in the frequency of stratospheric intrusions after solarH -flares is significant and completely independent of the phase of the solar cycle and season. The total atmospheric ozone shows also a correlation with solar flares: A well defined maximum on the day preceding the flare. The neutron density clearly shows the Forbush decrease on theH -key day. Using key days with Forbush minimum for the superposed epoch analysis reveals a significant maximum of the Be 7-concentration on the day before the flare (rise by about 45 to 60%).Notable is the following sequence: Approximately 3 days before the solar flare the neutron density begins to decrease, 1 to 2 days before the flare the total atmospheric ozone maximizes, and 2 to 3 days after the flare one finds the maximum of the Be 7 in the troposphere as a consequence of the stratospheric intrusion.Around days with maximum Be 7-concentration the reliability of weather forecasts is clearly reduced — a fact, which at this point is obviously indicative of an acute activation of a labile atmospheric condition.We selected some characteristic individual cases to demonstrate by means of tables the time lapse of typical solar atmospheric and geophysical variables associated with solar flares. The attendant structures of the vertical ozone profile are discussed.Some preliminary reflections on a physical link are set forth.

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Neue Ergebnisse über den Einfluß der Sonnenaktivität auf den stratosphärisch-troposphärischen Austausch

Zusammenfassung Anhand 8jähriger Registrierungen der Konzentration stratosphärischer Radionuklide und des Ozon in 3 km Höhe sowie des atmosphärischen Profils der Ozon-Konzentration und des Gesamt-Ozon wird die Abhängigkeit stratosphärischer Lufteinbrüche in die Troposphäre von solaren Ereignissen analysiert.Ein signifikanter, wenn auch schwacher Einfluß von Sektordurchgängen des interplanetarischen Magnetfeldes beim Polaritätswechsel vom Typ-/+ läßt sich nachweisen, jedoch geht ein jahreszeitlicher Einfluß mit ein.Signifikant und völlig unabhängig von der Phase des solaren Zyklus und der Jahreszeit ist die starke Zunahme der Häufigkeit bzw. der Stärke von stratosphärischen Lufteinbrüchen 2 bis 3 Tage nachH -Eruptionen (Zunahme um 50 bis 80%). Das atmosphärische Gesamt-Ozon zeigt ebenfalls eine Korrelation mitH -Eruptionen: Ein gut ausgeprägtes Maximum am Tag vor der Eruption wird festgestellt. Die Neutronendichte zeigt amH -Stichtag deutlich den Forbush-Effekt. Verwendet man Stichtage mit einem Forbush-Effekt für die Überlagerungs-Analyse, so findet man am Tage vor dem Stichtag ein signifikantes Maximum der Be 7-Konzentration (Anstieg um 45–60%). Auffallend ist die folgende Zeitfolge: Etwa 3 Tage vor derH -Eruption beginnt die Neutronendichte abzusinken, 1 bis 2 Tage vor der Eruption erreicht das atmosphärische Gesamt-Ozon das Maximum, 2 bis 3 Tage nach derH -Eruption findet man das Maximum des Be 7 in der Troposphäre als Folge der stratosphärischen Lufteinbrüche.Um Tage mit maximaler Be 7-Konzentration ist die Treffsicherheit von Wetterprognosen eindeutig reduziert. Man hat es also zu diesem Zeitpunkt offensichtlich mit der akuten Aktivierung eines labilen atmosphärischen Zustandes zu tun.Anhand von Tabellen wird der zeitliche Ablauf von charakteristischen solaren atmosphärischen und geophysikalischen Größen im Zusammenhang mit solaren Ereignissen für einige charakteristische Einzelfälle dargelegt. Die zugehörigen Strukturen des vertikalen Ozon-Profiles werden besprochen.Einige vorläufige Gedanken über einen Kausalzusammenhang werden dargelegt.

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With 12 Figures     

Land snails from the last glacial maximum on Andikithira,southern Greece and their palaeoclimatic implications

An assemblage of land snails from an aeolianite deposit on the coast of the southern Greek island of Andikithira is shown to date to 16 000 yr BP and thus represents the period of the last glacial maximum (LGM; Oxygen Isotope Stage 2). The assemblage has no modern analogue. Five of the ten species are extinct on the island and some of these now live only at high elevations (> 950 m). Significantly cooler temperatures, some 5-8°C below present, and slightly drier moisture conditions (lower rainfall, partially offset by reduced evapotranspiration at the lower temperature) are inferred. The large temperature depression at the LGM, well documented in northern and central Europe, extended also to the Mediterranean climate of southern Europe. Late Quaternary climatic changes had a considerable impact on the fauna of this isolated island.     

Cosmological parameter estimation and the spectral index from inflation

Accurate estimation of cosmological parameters from microwave background anisotropies requires high-accuracy understanding of the cosmological model. Normally, a power-law spectrum of density perturbations is assumed, in which case the spectral index n can be measured to around ± 0.004 using microwave anisotropy satellites such as MAP Planck . However, inflationary models generically predict that the spectral index n of the density perturbation spectrum will be scale-dependent. We carry out a detailed investigation of the measurability of this scale dependence by Planck , including the influence of polarization on the parameter estimation. We also estimate the increase in the uncertainty in all other parameters if the scale dependence has to be included. This increase applies even if the scale dependence is too small to be measured, unless it is assumed absent. We study the implications for inflation models, beginning with a brief examination of the generic slow-roll inflation situation, and then move to a detailed examination of a recently devised hybrid inflation model for which the scale dependence of n may be observable.     

Ein einfaches,universelles Gerät für luftelektrische Messungen und seine Anwendungsmöglichkeiten

Zusammenfassung Es wird ein einfaches Gerät für luftelektrische Untersuchungen beschrieben, das folgende Messungen bzw. Registrierungen auszuführen gestattet: 1) Registrierung des luftelektrischen Antennenstromes (Vertikalstrom); 2) Registrierung des luftelektrischen Feldes nach einer «halbstatischen» Methode; 3) Registrierung bzw. Zählung rascher zeitlicher Aenderungen des statischen Feldes (Feldsprünge bei el. Entladungen in der Atmosphäre). Die Anordnung besteht aus einem besonders konstruierten Röhrenvoltmeter, dessen Gehäuse Anzeigegerät und Stromversorgungen vercinigt. Die verschiedenen Fehlergrenzen der Messmethode werden eingehend dis kutiert. Das Gerät eignet sich zur Messung der Feldstärke bis ± 1500 V/m. Ein Einfluss der Windegeschwindigkeit auf die Feldanzeige besteht nach eingehenden Untersuchungen nicht. Zehntägige Anschlussregistrierungen im Erdmagnetischen Observatorium in Fürstenfeldbruck mit demBenndorf- Elektrometer erbrachten völlige Kurvengleichkeit der beiden Geräte. Einige Messbeispiele führen die Anwendungsmöglichkeiten des Gerätes vor Augen. Die gleichzeitige Registrierung des luftelektrischen Feldes an mehreren Stationen erbrachte sehr gute Uebercinstimmung im Kurvenverlauf, der durch die jcweiligen meteorologischen Verhältnisse bedingt war. Die Darstellung der mittleren Tagesgänge der Monate von 1949 und 1950 schliesst sich an.

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Summary A simple apparatus is described for measuring and recording the following data: 1) Vertical atmospheric current; 2) Atmospheric potential gradient (using a «half-static» method); 3) Frequency und shape of fast changes of the atmospheric potential gradient (at times of electric discharges in the atmosphere). The apparatus consists of a specially divised tube-voltmeter, combining current supply and reading instrument in one housing. Various error limits of the method are discussed. Potential gradients may be measured up to ±1500 volts per meter. Special investigations showed the wind velocity to have no influence on the measurements. 10 days' comparative records of this apparatus and theBenndorf-elektrometer of the Fürstenfeldbruck Geomagnetic Observatory showed complete identity of curves. Several examples of results obtained with the new intrument are given. Simultaneous records of atmospheric potential gradients at various places showed good agreement of curves obtained under similar meteorological conditions. Graphs of average daily variations during the months of 1949 and 1950 are also given.

     

The Global Earthquake Vulnerability Estimation System (GEVES): an approach for earthquake risk assessment for insurance applications

For the insurance and reinsurance industries, earthquake loss estimation is crucial not only to adequately price its product but also to manage the accumulation risk in the face of the ever-increasing exposure in highly seismic regions. Changes in the built environment and a continuously evolving earthquake science make it a necessity for the industry to constantly refine earthquake loss estimation models. In particular, it has been recognized for a long time that the vulnerability of buildings to ground shaking is a key parameter in any earthquake risk model. Current methods tend either to rely on the limited historical damage and loss data or on the numerical simulation of the response of individual buildings to the ground-shaking produced by earthquakes. Although both methods have their advantages and pitfalls, we are proposing here a simple solution, using transparent input data, that can be realistically used for the needs of the insurance and reinsurance industry, whether detailed information about the insured structures is available or not. The resulting product is known as GEVES (Global Earthquake Vulnerability Estimation System). It is primarily intended for evaluating the mean damage ratio (MDR) suffered by a portfolio of buildings classified by use, under the action of a given earthquake scenario (i.e. an earthquake of given size at a given distance from the portfolio of buildings). A key assumption was that macroseismic intensity rather than spectral displacement would be the basis of loss estimation. The paper describes the model with emphasis on its structure and the justification for the assumptions made. In addition to a new set of earthquake vulnerability functions, the paper also provides recommendations on some aspects of the earthquake hazard, in particular about how to define macroseismic intensity at the site of interest, for a given earthquake scenario. This paper also discusses validation of the GEVES model against calculated vulnerability approaches, and the treatment of uncertainty within the model.     

Prediction of the present-day stress field in the Australian continental crust using 3D geomechanical–numerical models

The Australian continent has an enigmatic present-day stress pattern with considerable regional variability in maximum horizontal stress (S_Hmax) orientations. Previous attempts to estimate the Australian S_Hmax orientation with geomechanical–numerical models indicate that plate boundary forces provide the major controls on the contemporary stress orientations. However, these models do not satisfactorily predict the observed stress orientation in major basins throughout eastern Australia, where the knowledge of the present-day crustal stresses is of vital importance for development and management of different types of geo-reservoirs. In addition, a new comprehensive stress-data compilation in Australia, which contains 2150 data records and is the key dataset for model calibration, provides motivation to construct a new geomechanical–numerical model for Australia. Herein, we present a 3D geomechanical–numerical model that predicts both the S_Hmax orientation and the relative stress magnitudes throughout the Australian continent. Our best-fit model, with mean absolute deviation of 15°, is in good agreement with observed S_Hmax orientations and the stress regime in most areas, and shows a much better fit in areas where the stress pattern was unable to be predicted by previous published attempts. Interestingly, the best-fit model requires a significant push from the western boundary of Australian continental model, which is possible supporting evidence for the east–west-oriented mantle drag postulated by state-of-the-art global convection models, or may be generated by the excess of gravitational potential energy from Tibetan Plateau, transferred through the Indo-Australian Plate. Hence, our modelling results provide a good first-order prediction of the stress field for areas where no stress information is currently available and can be used to derive initial and boundary conditions for local and reservoir-scale 3D geomechanical models across Australia.