Application of ERS-1 and Topex/Poseidon altimetry using precise orbits

The work described in this thesis concerns the application of radar altimetry, collected from the ERS-1 and TOPEX/POSEIDON missions, to precise satellite orbits computed at Aston University. The data is analysed in a long arc fashion to determine range biases, time tag biases, sea surface topographies and to assess the radial accuracy of the generated orbits through crossover analysis. A sea surface variability study is carried out for the North Sea using repeat altimeter profiles from ERS-1 and TOPEX/POSEIDON in order to verify two local U.K. models for ocean tide and storm surge effects. An on-side technique over the English Channel is performed to compute the ERS-1, TOPEX and POSEIDON altimeter range biases by using a combination of altimetry, precise orbits determined by short arc methods, tide gauge data, GPS measurements, geoid, ocean tide and storm surge models. The remaining part of the thesis presents some techniques for the short arc correction of long arc orbits. Validation of this model is achieved by way of comparison with actual SEASAT short arcs. Simulations are performed for the ERS-1 microwave tracking system, PRARE, using the range data to determine time dependent orbit corrections. Finally, a brief chapter is devoted to the recovery of errors in station coordinates by the use of multiple short arcs.

Combination of altimetry data from different satellite missions

Substantial altimetry datasets collected by different satellites have only become available during the past five years, but the future will bring a variety of new altimetry missions, both parallel and consecutive in time. The characteristics of each produced dataset vary with the different orbital heights and inclinations of the spacecraft, as well as with the technical properties of the radar instrument. An integral analysis of datasets with different properties offers advantages both in terms of data quantity and data quality. This thesis is concerned with the development of the means for such integral analysis, in particular for dynamic solutions in which precise orbits for the satellites are computed simultaneously. The first half of the thesis discusses the theory and numerical implementation of dynamic multi-satellite altimetry analysis. The most important aspect of this analysis is the application of dual satellite altimetry crossover points as a bi-directional tracking data type in simultaneous orbit solutions. The central problem is that the spatial and temporal distributions of the crossovers are in conflict with the time-organised nature of traditional solution methods. Their application to the adjustment of the orbits of both satellites involved in a dual crossover therefore requires several fundamental changes of the classical least-squares prediction/correction methods. The second part of the thesis applies the developed numerical techniques to the problems of precise orbit computation and gravity field adjustment, using the altimetry datasets of ERS-1 and TOPEX/Poseidon. Although the two datasets can be considered less compatible that those of planned future satellite missions, the obtained results adequately illustrate the merits of a simultaneous solution technique. In particular, the geographically correlated orbit error is partially observable from a dataset consisting of crossover differences between two sufficiently different altimetry datasets, while being unobservable from the analysis of altimetry data of both satellites individually. This error signal, which has a substantial gravity-induced component, can be employed advantageously in simultaneous solutions for the two satellites in which also the harmonic coefficients of the gravity field model are estimated.

Is education the panacea for economic deprivation of Muslims? Evidence from wage earners in India, 1987-2005

Few researchers have examined the nature and determinants of earnings differentials among religious groups, and none has been undertaken in the context of conflict-prone multi-religious societies like the one in India. We address this lacuna in the literature by examining the differences in the average log earnings of Hindu and Muslim wage earners in India, during the 1987–2005 period. Our results indicate that education differences between Hindu and Muslim wage earners, especially differences in the proportion of wage earners with tertiary education, are largely responsible for the differences in the average log earnings of the two religious groups across the years. By contrast, differences in the returns to education do not explain the aforementioned difference in average log earnings. In conclusion, we discuss some policy implications.

Transgressing community:the case of Muslims in a twenty-first-century British city

This paper draws on ethnographic research carried out in Birmingham, UK – a city significant for its sizeable Muslim population and its iconic role in the history of minority ethnic settlement in Britain – to consider how associations of place and ethnicity work in different ways to inform ideas about ‘Muslim community’ in twenty-first-century Britain. The paper charts happenings around a local event in an area of majority Asian settlement and how representations of the area as a place of Muslim community were used to implicate it in the ‘war on terror’. The paper goes on to show how this sensibility is disrupted by Muslims themselves through alternative engagements with space and ethnicity. The paper argues that these offer a ground for making Muslim community in ways that actively engage with histories and patterns of ethnic settlement in the city rather than being determined by them.

Transgressing community:the case of Muslims in a twenty-first-century British city

This paper draws on ethnographic research carried out in Birmingham, UK - a city significant for its sizeable Muslim population and its iconic role in the history of minority ethnic settlement in Britain - to consider how associations of place and ethnicity work in different ways to inform ideas about 'Muslim community' in twenty-first-century Britain. The paper charts happenings around a local event in an area of majority Asian settlement and how representations of the area as a place of Muslim community were used to implicate it in the 'war on terror'. The paper goes on to show how this sensibility is disrupted by Muslims themselves through alternative engagements with space and ethnicity. The paper argues that these offer a ground for making Muslim community in ways that actively engage with histories and patterns of ethnic settlement in the city rather than being determined by them.