Land fragmentation due to rapid urbanization in the Phoenix Metropolitan Area: Analyzing the spatiotemporal patterns and drivers

Rapid urbanization of the Phoenix Metropolitan Area exemplifies the dominant US Southwest urban growth pattern of the past six decades. Using a combination of multitemporal land cover data, gradient analysis, and landscape metrics, we quantify and characterize spatiotemporal patterns of land fragmentation observed in Phoenix. We analyze historical, qualitative data to identify five major socio-ecological drivers critical to understanding the urbanization processes and fragmentation patterns: population dynamics, water provisioning, technology and transportation, institutional factors, and topography. A second objective is to assess the applicability and accuracy of National Land cover Database (NLCD)-—a widely used land cover dataset—-to detect and measure urban growth and land fragmentation patterns in the relatively treeless desert biome of the US Southwest. In contrast to studies in the temperate eastern USA where NLCD has proved inaccurate for detection of exurban development, our study demonstrates that NLCD is a reliable data source for measuring land use in the southwest, even in low-density environments. By combining qualitative analyses of social-ecological drivers with fragmentation analyses, we move toward an improved understanding of urbanization and insights on the human modification framework used widely in land change science.     

A survey of magnetopause FTEs and associated flow bursts in the polar ionosphere

Using the Equator-S spacecraft and SuperDARN HF radars an extensive survey of bursty reconnection at the magnetopause and associated flows in the polar ionosphere has been conducted. Flux transfer event (FTE) signatures were identified in the Equator-S magnetometer data during periods of magnetopause contact in January and February 1998. Assuming the effects of the FTEs propagate to the polar ionosphere as geomagnetic field-aligned-currents and associated Alfveén-waves, appropriate field mappings to the fields-of-view of SuperDARN radars were performed. The radars observed discrete ionospheric flow channel events (FCEs) of the type previously assumed to be related to pulse reconnection. Such FCEs were associated with 80% of the FTEs and the two signatures are shown to be statistically associated with greater than 99% confidence. Exemplary case studies highlight the nature of the ionospheric flows and their relation to the high latitude convection pattern, the association methodology, and the problems caused by instrument limitations.     

ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes

We report observations of the cusp/cleft ionosphere made on December 16th 1998 by the EISCAT (European incoherent scatter) VHF radar at Troms and the EISCAT Svalbard radar (ESR). We compare them with observations of the dayside auroral luminosity, as seen by meridian scanning photometers at Ny Ålesund and of HF radar backscatter, as observed by the CUTLASS radar. We study the response to an interval of about one hour when the interplanetary magnetic field (IMF), monitored by the WIND and ACE spacecraft, was southward. The cusp/cleft aurora is shown to correspond to a spatially extended region of elevated electron temperatures in the VHF radar data. Initial conditions were characterised by a northward-directed IMF and cusp/cleft aurora poleward of the ESR. A strong southward turning then occurred, causing an equatorward motion of the cusp/cleft aurora. Within the equatorward expanding, southward-IMF cusp/cleft, the ESR observed structured and elevated plasma densities and ion and electron temperatures. Cleft ion fountain upflows were seen in association with elevated ion temperatures and rapid eastward convection, consistent with the magnetic curvature force on newly opened field lines for the observed negative IMF B_y. Subsequently, the ESR beam remained immediately poleward of the main cusp/cleft and a sequence of poleward-moving auroral transients passed over it. After the last of these, the ESR was in the polar cap and the radar observations were characterised by extremely low ionospheric densities and downward field-aligned flows. The IMF then turned northward again and the auroral oval contracted such that the ESR moved back into the cusp/cleft region. For the poleward-retreating, northward-IMF cusp/cleft, the convection flows were slower, upflows were weaker and the electron density and temperature enhancements were less structured. Following the northward turning, the bands of high electron temperature and cusp/cleft aurora bifurcated, consistent with both subsolar and lobe reconnection taking place simultaneously. The present paper describes the large-scale behaviour of the ionosphere during this interval, as observed by a powerful combination of instruments. Two companion papers, by Lockwood et al. (2000) and Thorolfsson et al. (2000), both in this issue, describe the detailed behaviour of the poleward-moving transients observed during the interval of southward B_z, and explain their morphology in the context of previous theoretical work.     

Between social and spatial convergence and divergence: an exploration into the political geography of European contact areas

The European continent, the motherland of nationalism, and the part of the world where political borders and different territorial and cultural identities are mostly interrelated, is now facing new challenges regarding how best to represent its numerous interests within one system. With the increase of international integration European countries began to devote greater attention to the development problems of their border areas that had to be helped to undertake certain functions in the international integration process. The fostering of a more balanced regional development also resulted in a strengthening of regional characteristics, which the new model could no longer ignore. Regional characteristics in turn have always been preserved in Europe by persistent historical and cultural elements of ethnic and linguistic variety. Therefore, it is not surprising that the process of European integration based on the new regional development model was accompanied by a parallel process of ethnic or regional awakening of minorities and other local communities. The key question for contemporary European (though of course this is not limited to Europe) political geography is, then, how the process summarised under the twin labels of social convergence and deterritorialisation will effect the persistent maintenance of regional identities and the corresponding divergence of regional spaces. Or, in other words: is the ‘unity in diversity’ European programme ever practicable and exportable on a world-wide scale or are we to be absorbed by a new global ‘melting pot’?     

The impact of environmental factors on the distribution pattern of aquatic plants along the Danube River corridor (Slovakia)

The aim of the study was to evaluate pattern of the aquatic macrophyte species distribution along the Danube fluvial corridor in Slovakia, and to identify the impact of environmental abiotic parameters on macrophyte species diversity. Field sampling was performed in the period 1999–2005 from the boat. Aquatic habitats were divided into 365 survey unit (SU). The survey of aquatic macrophytes and abiotic parameters followed the European standard approach EN 144184 2003. The plant mass estimate (PME – a semi-quantitative estimation of the amount of individual species in a SU, which takes into account three-dimensional development of plant stands) was estimated according to a five-point-scale in each SU; environmental pattern, were assessed over six abiotic parameters (river km, bank type, sediment type, flow velocity class, land-use type, and heavily man-modified water bodies). Altogether, four hydrologic connectivity types of aquatic habitats were distinguished: the Danube River, Open Arms, Separated Arms, and Seepage Water-bodies.

In total, 54 aquatic macrophytes were recorded for the whole data set of the Danube fluvial corridor. The PME data of true aquatic macrophytes and the length of SUs created a basis for numerical derivates, relative plant mass (RPM), mean mass indices (MMT, MMO) and the distribution ratio (d).

The results correspond with comparable studies on this topic: the highest macrophytes species diversity occurred in Separated Arms. On the contrary, macrophytes had the lowest richness in the Danube River main channel, although their diversity was slightly higher in heavily man-modified water bodies (such as the hydropower plant's reservoir and the abandoned main channel of the so-called Old Danube). Our results suggest that the lateral connectivity types of the river water bodies, primarily characterised by different hydrologic dynamics and human impact expressed as land-use types are responsible for the variability of aquatic macrophyte assemblages along the Danube corridor in Slovakia.     

Global geodynamic long-term variations and expanding earth hypothesis

Summary The expanding Earth hypothesis has been discussed on the basis of recent LLR data and the long-term decrease observed in the angular velocity of the Earth's rotation. It has been proved that the observed data do not support the hypothesis. Realistic limits for hypothetical long-term variations in the Earth's dimension consistent with observations have been derived as ±3 × 10^–3 m cy^–1.     

Bestimmung der Dimensionen des Erdellipsoids aus den Europäischen Astronomischgeodätischen Netzen

Резюме Сообщаются результаты исследований по выводу размеров земного эллипсоида по градусным измерениям стран Европы, выполненном двумя методами: методом площадей на основе принципа развертывания (решение I) и методом площадей на основе принципа проектирования (решение II). В гл. I рассматривается теория обоих методов. В классическую теорию метода площадей на основе принципа развертывания (раздел 2) не вносятся существенные изменения. Но коэффициенты соответствующих уравнений градусных измерений, являющиеся функциями геодезических координат и длины и азимута геодезической линии, преобразованы и представлены в виде функций только геодезических координат концов этой линии. Это внесло боляшое облегчение в вычислительную работу, т. к. главные члены формул получили простой вид, а поправочные члены оказалось возможным решить графическим путем. В теории метода площадей на основе принципа проектирования (раздел 3) выведено выражение для поправки большой полуоси эллипсоида в виде функции координат центра нового эллипсоида и поправки сжатия. Точность этого выражения порядка расстояния старого и нового эллипсоидов в исходном пункте. В разделе 4 дана теория преобразования системы уклонений отвеса при методе развертывания в систему уклонений отвеса при методе проектирования, исходя из исследований Молоденского [4] (способ I), и используя дифференциальные формулы при методах развертывания и проектирования (способ II). Гл. II содержит очень краткое описание градусных измерений, выполненных в странах Европы. В гл. III изложены некоторые числовые результаты всей выполненной работы. В гл. IV даются некоторые выводы и заключения на основе полученных результатов. Прежде всего отмечается практически полное совпадение значений параметров эллипсоида, выведенных методом площадей на основе принципа развертывания и методом площадей на основе принципа проектирования. Влияние эффекта развертывания на величину большой полуоси эллипсоида при выводе на основе принципа проектирования и с использованием обычной системы смешанных уклонений отвеса в Европе равно применро 15м (табл. 4). Относительно вывода сжатия эллипсоида отмечается, что его точность мала вследствие неблагоприятного расположения использованных градусных измерений. Этот факт иллюстрирустся тем, что изменение сжатия на 1 единису в его знаменателе вызывает изменение большой полуоси лишь в 4–8м (табл. 5). По выводу элементов ориентировки эллипсоида отмечается, что во всех решенных вариантах их значения практически одинаковы, и что влияние эффекта развертывания здесь ничтожно. Наиболее достоверными считаются результаты вывода в варианте В, т. е. Без использования наблюдений астрономических азимутов. Средние из значений параметров, выведенных при использовании принципа проектирования и принципа развертывания в этом варианте даны уравнениями (32)–(34). Приведенные результаты показывают, что ни эллипсоид Бесселя и ни эллипсоид Хейфорда не подходят для астрономо-геодезических сетей Европы. Можно заключить, что для этой цели эллипсоид Красовского более подходит, чем какой—нибудь другой из известных эллипсоидов. Как известно, в европейских странах народной демократии этот эллипсоид уже применяется. Его применение в Европе является научно обоснованным.

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Anschrift: Kostelní 42, Praha 7.     

Tidal evolution and hydrostatic equilibrium of phobos

Summary A dynamical model of Phobos has been set up: its boundary surface is defined by the 2nd degree Stokes zonal and sectorial parameters, the mass and angular velocity of rotation of the body (assumed homogeneous), plus the constant part of the tidal potential due to Mars which is relatively very large. The tidal evolution has been outlined, based on the condition that, at a certain epoch, the sum of the tidal and centrifugal forces on the surface of Phobos should be equal to the gravitation of opposite sign. The problem of hydrostatic equilibrium of Phobos is discussed.

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