On Joule heating of the equatorial electrojet E-region

Simultaneous data on electron density, electron temperature and current density obtained from a rocket borne Langmuir probe, a glass-sealed Langmuir probe and a proton precession magnetometer flown from Thumba (geomag. lat. 0.99°S, geomag. long. 146.79°E, magnetic dip 0°47'S) have been used to calculate the Joule heating in order to assess whether it contributes significantly to the thermal imbalance in the E-region. It is envisaged that the changes in electron temperature are partially brought about by changes in collision frequency and the energy loss factor. It is found that the Joule heating alone is not sufficient to explain the observed differences in electron and neutral gas temperatures. The inclusion of photoelectron heating and adjustments of profiles of the collision frequency and the energy loss factor bring the computed temperature differences closer to the observed differences.     

Polar thermospheric Joule heating,and redistribution of recombination energy in the upper mesosphere

Kellogg, W. W. (1961, J. Met. 18, 373) suggested that transport of atomic oxygen from the summer into the winter hemisphere and subsequent release of energy by three body recombination, O + O + N₂→O₂ + N₂ + E, may contribute significantly to the so-called mesopause temperature anomaly (increase in temperature from summer to winter). Earlier model calculations have shown that Kellogg's mechanism produces about a 10% increase in the temperature from summer to winter at 90 km. This process, however, is partly compensated by differential heating from absorption of UV radiation associated with dissociation of O₂. In the auroral region of the thermosphere, there is a steady (component of) energy dissipation by Joule heating (with a peak near 130 km) causing a redistribution and depletion of atomic oxygen due to wind-induced diffusion. With the removal of O. latent chemical energy normally released by three body recombination is also removed, and the result is that the temperature decreases by almost 2% near 90 km. Through dynamic feedback, this process reduces the depletion of atomic oxygen by about 25% and the temperature perturbation in the exosphere from 10% to 7% at polar latitudes. Under the influence of the internal dynamo interaction, the prevailing zonal circulation in the upper thermosphere (small in magnitude) changes direction when the redistribution of recombination energy is considered. The above described effects are very sensitive to the adopted rates of eddy diffusion. They are also strongly time dependent and are significantly reduced for disturbances associated with magnetic storms.     

Polar cap potential distributions during periods of positive IMF By and Bz

We compare the DE-2 electric field measurements used by Heppner and Maynard [(1987) J. geophys. Res.92, 4467] to illustrate strongly distorted, BC convection patterns for IMF B_z > 0 and large |B_y|, with simultaneous detections of particle spectra, plasma drifts and magnetic perturbations. Measured potentials >50 keV, driven by the solar wind speeds exceeding 500 km/s, are greater than published correlation analysis predictions by up to 27%. The potential distributions show only two extrema and thus support the basic conclusion that under these conditions the solar wind/IMF drives two- rather than fourcell convection patterns. However, several aspects of the distorted two-cell convection pattern must be revised. In addition to the strong east-west convection in the vicinity of the cusp, indicated by Heppner and Maynard, we also detect comparable components of sunward (equatorward) plasma flow. Combined equipotential and particle precipitation distributions indicate the presence of a lobe cell embedded within the larger, afternoon reconnection cell. Both types rotate in the same sense, with the lobe cell carrying 20–40% of the total afternoon cell potential. We detected no lobe cell within morning convection cell.     

Challenging the grammar of difference: Benoy Kumar Sarkar,global mobility and anti-imperialism around the First World War

The new imperial history has advanced our understanding of empires in many ways: it enhanced a networked interpretation of empires, brought space back into the discussion, and suggested a fresh reading of imperial careers to comprehend early forms of global inter-dependencies. This article discusses selected aspects of the life and work of Benoy Kumar Sarkar (1887–1949), a Bengali social scientist and political activist, to illustrate that anti-imperial biographies were simultaneously rooted in local as well as transnational spaces. They thus connected national struggles with globe-spanning processes. Biographies like this are underacknowledged in their meaning for how empires functioned and failed, and in their potential for understanding transnational actors. Sarkar’s efforts to challenge the legitimacy of the British Empire were the result of his life in a transnational social field, which was equally shaped by his extensive experience abroad and his continuous rootedness in local Bengali affairs. Sarkar’s anti-imperialism was enhanced by the mobility structures of the British Empire and resulted in new constellations of imperial, cosmopolitan, local and regional orientations and attachments. In this view, anti-imperialism was less the result of local struggles but of life practices reaching beyond the borders of the empire and a high awareness of acting in a global context that located its protagonists in numerous social and spatial contexts.     

Geography and the construction of difference

There is growing evidence of ‘horizontal hostilities’ among women: many women are affirming their identities along axes of class, race, sexuality, age and/or relationship to colonialism. Within recent feminist writing, geography—space, place and location—has been used as a vehicle for rethinking a feminist affinity that does not erase or undermine ‘difference’. We review contemporary uses of geographical metaphors and caution against an excessive emphasis on displacement as a metaphor for a critical feminist stance. We argue that geographies of placement must be held in tension with an ideal of displacement. We develop this point through a case study of women and work in contemporary Worcester, Massachusetts. Women in Worcester are very much rooted in place and this is a vehicle for the construction of differences across women. We argue that studies of the construction of feminine identities in particular places counteract the current tendency within feminism to rigidify differences among women and are an important means of rebuilding affinities among women.     

The potential and pitfalls of global environmental governance: The politics of transfrontier conservation areas in Southern Africa

This article examines the potential and problems associated with global environmental governance with particular reference to Transfrontier Conservation Areas (TFCAs) in Southern Africa. By taking a political ecology approach, it reflects on theories and practices of global environmental governance through an analysis of transboundary environmental management. In particular, it examines the politics of the struggle over control of and access to key natural resources and how it impacts on the implementation of transfrontier conservation. In order to do this, this article includes an analysis of the complex role of local and global NGOs, the changing role of the state in relation to international actors, the importance of community based natural resource management, the commitment to tourism to make conservation pay its way and the problems associated with illicit networks of traffickers of wildlife products, cars and people.It is important to investigate the politics of TFCAs because they are part of a wider context of increasing forms of transnational management of the environment; such transnational forms of management are often deemed to be more effective than national level management because of the transboundary nature of environmental problems. This article argues that the assumption that transnational management can be neatly implemented needs rethinking. In particular, it highlights the ways that complex networks of actors constitute a significant challenge to global environmental governance. This in turn raises more general questions about the effectiveness of other forms of global environmental governance centred on managing problems such as climate change, pollution or trafficking of endangered species and tropical hardwoods.     

Language,religion and the politics of difference

Language and religion are arguably the two most socially and politically consequential domains of cultural difference in the modern world. Yet there have been very few efforts to compare the two in any sustained way. I begin by aligning language and religion, provisionally, with ethnicity and nationhood, and by sketching five ways in which language and religion are both similar to and similarly intertwined with ethnicity and nationhood. I then identify a series of key differences between language and religion and draw out their implications for the political accommodation of cultural heterogeneity. I show that religious pluralism tends to be more intergenerationally robust and more deeply institutionalised than linguistic pluralism in western liberal democracies, and I argue that religious pluralism entails deeper and more divisive forms of diversity. The upshot is that religion has tended to displace language as the cutting edge of contestation over the political accommodation of cultural difference – a striking reversal of the longer‐term historical process through which language had previously displaced religion as the primary focus of contention.     

Mothers,communities and the scale of difference

Only recently did geographic concern turn to why and how, and when and where political identities are reproduced but, as yet, our understanding of the political relations between families and communities remains understudied. This lack of attention is attributable, in part, to the complexities of families and communities but, this aside, all societies regulate reproduction and there are always claims for legitimization of particular views of family values and community relations. With this paper, I argue that highlighting the social construction of scale suggests ways that the social imaginary of a domestic myth is spatially embedded within a nurturing local community. I outline some recent feminist discussion of local childcare cultures and critique of 'the public sphere' prior to raising scale as a way to open up static versions of justice and difference. Arguments in the paper that relate to the social construction of scale are illustrated by examples from a study of the impact of a new child and a residential move on mothers in San Diego. I argue that although the birth of a child highlights important questions that relate to responsibility, self-identity and notions of family, community and society, it is from within a politically structured notion of scale that many of the constraints and contexts of childcare arise. This paper focuses specifically on negotiating childcare as a basis of resistance through day-to-day contestations at multiple scales.     

JFK and the future of global leadership

On 10 June 1963 President John F. Kennedy gave a speech that changed the world. His commencement speech at American University helped to spur the signing of a world‐changing agreement between the Soviet Union and the United States—the Partial Nuclear Test Ban Treaty. This episode of peacemaking is remarkable for two reasons. First, it arguably helped to save the world, since the nuclear confrontation at that stage of the Cold War was not a ‘stable balance of terror’, as sometimes described, but rather a highly unstable situation that was prone to accidents, misjudgements and potential disasters. Second, this was an episode of statesmanship in which presidential leadership played a crucial role. Following the Cuban Missile Crisis, Kennedy understood that he bore sole responsibility on the US side to find a way back from the brink of nuclear war. He used the ‘peace speech’ to create a novel kind of peace diplomacy, and worked together with his counterpart, Soviet leader Nikita Khrushchev, to pull the superpowers back from this precarious brink.     

Mabo,freedom and the politics of difference

This paper attempts to demonstrate the applicability of certain themes from post‐structuralist theory to issues raised by the Mabo judgment and the subsequent debate over native title. It outlines some common features of a post‐structuralist conception of society, commenting particularly on conceptions of freedom and the shared concern with difference. It then shows how questions of difference and identity raised by Mabo may be described in post‐structuralist terms, and contrasts the treatment of difference by Derrida and Deleuze from a political point of view. Finally, the paper suggests ways in which Mabo may be seen as a significant event, and an exercise of freedom, in Deleuzian terms.     

Mapping the spatial pattern of the uncertain data in urban areas: The disadvantaged predict global nonresponse rate in the National Household Survey

High levels of survey nonresponse potentially produce unreliable data due to the often indeterminable possibility of such data being subject to nonresponse bias. In this paper, spatial patterns of global nonresponse rate are analyzed in order to identify whether systemic bias exists across urban spaces with regard to survey nonresponse. Forward stepwise regression is used in combination with spatial regression analysis to build models enabling the prediction of global nonresponse rates in the voluntary 2011 National Household Survey based on explanatory employment, housing, income, and other variables within 11 Canadian cities. The modelling process underscores the inequity of global nonresponse rates; places with high unemployment, high rates of rental properties, a higher proportion of Aboriginal residents, and lower educational attainment have lower compliance with the voluntary survey. Such a pattern has the potential to dramatically influence the ability of government, non-governmental organizations, and other service providers to address the needs of residents of such urban areas.     

Altitude and latitude dependence of the equatorial electrojet

The effects of day-to-day or seasonal variation of altitude and latitude profiles of the Elayer plasma density in the equatorial ionosphere on equatorial electrojet (EEJ) structure are examined numerically using a self-consistent and high resolution dynamo model. It is found that variations in the E-layer peak altitude and amplitude and its gradient below significantly affect EEJ structure. For any realistic shape, the EEJ peak appears at or below the E-layer peak altitude. Distinct double peaks appear in the EEJ structure, such as revealed by rocket measurements, if the E-layer peak is above 105 km or the gradient is large, as when sporadic-E is present. The influence of the latitudinal variation of ionospheric field line integrated conductivities upon the amplitude and altitude of the EEJ peak is demonstrated.     

Europe and the new balance of global order

The European Union has become an important shaping factor in international relations, but how and under what conditions it can exercise influence and contribute constructively to global order are still not well analysed. In fact, the EU's contribution may resemble more that of a force in physics than of a great power in the traditional sense of international relations (which the EU is not, and will not become in the near future), and its influence depends probably more on what the EU represents and how well it manages its own realm, rather than on what it can do externally. In this sense, European influence in international relations presently benefits from past achievements, and may therefore have peaked if the twin challenges of enlargement and national structural deficiencies are not addressed effectively. But even if the European Union does master those challenges successfully, and thus manages to sustain and perhaps even enhance its influence as a force in international relations, it will still have to proceed cautiously and clearly focus its attempts on shaping its external environment and contributing to a ‘concrete’ or ‘civilized’ global order. In a global setting that, despite appearances to the contrary, seems characterized by a diffusion rather than a concentration of power and by strong tendencies towards entropy rather than order, the EU can and will probably not remain America's principal ally in sustaining Pax Americana. Nor does it seem likely to become an equal partner in a constructive, balanced transatlantic relationship, let alone a great power capable of challenging, perhaps together with others, America's apparent pre‐eminence. The most plausible assumption for the EU's future role in the new balance of global order is that of a ‘civilian force’ with a regional focus. It may best be able to contribute to global order by managing its own realm well, promoting the normative and institutional infrastructure for civilized international relations, not least in the sense of functioning statehood, and working towards effective multilateralism.     

Ionospheric and atmospheric disturbances around Japan caused by the eruption of Mount Pinatubo on 15 June 1991

The disturbances observed by the Japanese ionospheric observation network following the explosions of Mount Pinatubo on 15 June 1991, are presented. Remarkable ionospheric fluctuations with periods of about 20 min appeared in the records of HF Doppler and total electron content (TEC) data. Traveling wave fronts of ionospheric disturbances scaled from these data give a northward horizontal velocity of 290 m/s. The surface pressure fluctuations due to the passage of atmospheric waves were confirmed by the microbarograph chain data in Japan. There existed three kinds of northward traveling pressure fluctuations; short-period (2–5 min) fluctuations with a horizontal velocity of 290 m/s, long-period (8–10 min) fluctuations with 300 m/s, and 17-min fluctuations with 281 m/s. It is concluded that the ionospheric and surface pressure waves were caused by the eruption of Mount Pinatubo.     

On the global and regional behaviour of the mid-latitude ionosphere

Data from a chain of seven ionosondes in the range of 56–38 N and 1–38° E geographic coordinates were analysed to illustrate the global and regional behaviour of the mid-latitude F-region for some selected geomagnetic storms that occurred during the solar cycle 21. It was found that there are different spatial scales in the response of the mid-latitude ionosphere to the disturbance in the magnetosphere-ionosphere thermosphere system. The physical mechanisms and processes are discussed in relation to the relevance of various theories in the understanding of the dynamics of ionospheric storms.     

Racialising global relations: the Rwandan genocide and the ethics of representation

At a time when the historical experience of the Rwandan genocide continues to be invoked to imagine and affirm international responsibility for the suffering of others, this article examines one way in which this event has been made to mean. Through a critical reading of Hotel Rwanda (a feature film) and Shake Hands with the Devil (a memoir), the article examines how the Rwandan genocide has been framed as an event of ‘white’ Western racism towards ‘black’ African injury. Without disputing the veracity of this explanatory framework, this article interrogates its representational politics and ethics. I problematise its continued use of inherently discriminatory racial categories, demonstrate its Eurocentric nature and call for a mode of understanding the ethical significance of the Rwandan genocide that is not limited to an already existing global relation between suffering ‘black’ bodies and potential ‘white’ saviours. In critiquing these texts and this discursive framework, my aim is to enable ways of coming to terms with the genocide that can accommodate the complex connections that do and may exist between non-Rwandans and the 1994 Rwandan genocide.     

Computation of the zonally-averaged circulation driven by heating due to radiation and turbulence

In a zonally-averaged dynamic model the steady state circulation of the middle atmosphere between 10 and 110 km altitude has been calculated for solstice. To investigate the combined effect of turbulent heat conduction and dissipation of eddy kinetic energy on the mean circulation, the dissipative heating has been parameterized in terms of the buoyancy term modified by a residual Richardson number. It is shown that turbulence will result in net heating of the mesopause region to be consistent with a zero mass flux through a pressure surface. It is also demonstrated that the combined effect of turbulent heat conduction and dissipation can modify the mean circulation remarkably if the Richardson number is made latitude-dependent.     

Observation and theoretical modelling of a region of downward field-aligned flow of O+ in the winter dayside polar cap

Combined optical and radar measurements of ion drift at high latitudes near the terminator show that large downward field-aligned ion flows occur below the F-peak. At an invariant latitude of 72° and in the local time period from 1100 to 1500, downward velocities of 400 m s ⁻¹ have been observed. At the same time, the poleward component of field-perpendicular ion velocity was only 100 m s ⁻¹. The high latitude ionospheric model of Queganet al. (1982), as modified by Allenet al. (1984), predicts downward field-aligned velocities with the same sign morphology as the observations, but with only one fifth of the magnitude. However, the existence of downward neutral winds might lead to non-linear amplification of the downward ion motion. Using the vertical wind measurements of Reeset al. (1984), a possible explanation of the fast ion flow is suggested.