Intraseasonal oscillations and interannual variability of surface winds over the Indian monsoon region

The role of intraseasonal oscillations (ISOs) in modulating synoptic and interannual variations of surface winds over the Indian monsoon region is studied using daily averaged National Centers for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) reanalyses for the period 1987–1996. Two dominant ISOs are found in all years, with a period between 30–60 days and 10–20 days respectively. Although the ISOs themselves explain only about 10–25% of the daily variance, the spatial structure of variance of the ISOs is found to be nearly identical to that of high frequency activity (synoptic disturbances), indicating a significant control by the ISOs in determining the synoptic variations. Zonal and meridional propagation characteristics of the two modes and their interannual variability are studied in detail. The synoptic structure of the 30–60 day mode is similar in all years and is shown to be intimately related to the strong (‘active’) or weak (‘break’) phases of the Indian summer monsoon circulation. The peak (trough) phase of the mode in the north Bay of Bengal corresponds to the ‘active’ (‘break’) phase of monsoon strengthening (weakening) the entire large scale monsoon circulation. The ISOs modulate synoptic activity through the intensification or weakening of the large scale monsoon flow (monsoon trough). The peak wind anomalies associated with these ISOs could be as large as 30% of the seasonal mean winds in many regions. The vorticity pattern associated with the 30–60 day mode has a bi-modal meridional structure similar to the one associated with the seasonal mean winds but with a smaller meridional scale. The spatial structure of the 30–60 day mode is consistent with fluctuations of the tropical convergence zone (TCZ) between one continental and an equatorial Indian Ocean position. The 10–20 day mode has maximum amplitude in the north Bay of Bengal, where it is comparable to that of the 30–60 day mode. Elsewhere in the Indian Ocean, this mode is almost always weaker than the 30–60 day mode. In the Bay of Bengal region, the wind curl anomalies associated with the peak phases of the ISOs could be as large as 50% of the seasonal mean wind curl. Hence, ISOs in this region could drive significant ISOs in the ocean and might influence the seasonal mean currents in the Bay. On the interannual time scale, the NCEP/NCAR reanalysed wind stress is compared with the Florida State University monthly mean stress. The seasonal mean stress as well as interannual standard deviation of monthly stress from the two analyses agree well, indicating absence of any serious systematic bias in the NCEP/NCAR reanalysed winds. It is also found that the composite structure of the 30–60 day mode is strikingly similar to the dominant mode of interannual variability of the seasonal mean winds indicating a strong link between the ISOs and the seasonal mean. The ISO influences the seasonal mean and its interannual variability either through increased/decreased residence time of the TCZ in the continental position or through occurrence of stronger/weaker active/break spells. Thus, the ISOs seem to modulate all variability in this region from synoptic to interannual scales.     

Modelling the responses of mature forest trees to air pollution

Systems analysis of the responses of forest trees to air pollutants led to mathematical models which represent the essential life processes of mature trees (photosynthesis, respiration, growth etc.) under ‘normal’ conditions and — especially — under pollution strees. Computer simulations using these models have made it possible to test and analyse the consequences of — known or hypothetical — pollution effects. The simulation runs have led to the identification of three distinct behavioural modes (growth, stagnation, breakdown) and corresponding stable and unstable system states. The results have produced new insights and contributed to the understanding of the dieback process of spruce and beech trees. The presentation will concentrate on the most recent and most complex of the hitherto existing models, theBeech model.     

A Comparative Analysis of Main Modes of Global-scale Sea Surface Temperature on Multiple Time Scale

Using the HadISST data from 1880 to 2009, removed the signal of global warming in one hundred year. The results show that, there were the significant interannual and interdecadal oscillation signal at the eastern Pacific and north Pacific and north Atlantic, especially the decadal oscillation in the south of eastern equatorial Pacific cannot be ignored. We found there are three major global-scale signals by using the Empirical Orthogonal Function (EOF) analysis on global sea surface temperature, the first mode is (ENSO-like/PDO-like) Pacific pattern, the second mode is (AMO-like) the north Atlantic pattern and the third mode is (ENSO Modoki-like/CP ENSO-like) Center Pacific Ocean pattern. In particular, the third mode is the performance of Center Pacific El Niño-Southern Oscillation in the global mode. There are significant signals in interannual and interdecadal scales, in the unfiltered conditions, the three modes can explain 34% of total variance contribution. Above the interdecadal scale, the sum of three modes variance contribution is 61%. In various time scales, the three signals and the average global temperature has a connection, especially the influence of the first and second mode is the most important, in the decadal scale, the sum of the first and second modal variance contribution is 50%. Since 2005, there is no significant signal of global warming may be associated with the simultaneous decline of the first two modes.     

The Asia-Pacific Rim's transport and telecommunications systems: spatial structure and corporate control since the mid-1980s

There is a need to move from discussing the Asia-Pacific Rim's leading port cities as shipping centres measured by container throughput. This shift in focus involves examining how different transport and telecommunications systems are interacting with each other at an international scale under the power and control of major world operators. Using a three-level network framework an attempt is made to illustrate and explain the formation of multilayered trade/communications corridors and hubs/headquarters in the Asia-Pacific Rim since the mid-1980s and to identify the factors affecting them. From this examination of spatial structure and corporate control three levels of cities in the Asia-Pacific Rim are recognised: first level cities with strong corporate representation in container shipping, air cargo, air passenger and telecommunications; second level cities with marked corporate representation in one but not all four modes; and third level cities with no marked corporate representation in any mode but with strong throughput. The third level includes the Asia-Pacific Rim's ‘true’ port cities. Perhaps the ambiguous category ‘port city’ should be reserved for them. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mechanisms of variability and predictability of the tropical coupled ocean-atmosphere system

A conceptual model is proposed to explain the observed aperiodicity in the short term climate fluctuations of the tropical coupled ocean-atmosphere system. This is based on the evidence presented here that the tropical coupled ocean-atmosphere system sustains a low frequency inter-annual mode and a host of higher frequency intra-seasonal unstable modes. At long wavelengths, the low frequency mode is dominant while at short wavelengths, the high frequency modes are dominant resulting in the co-existence of a long wave low frequency mode with some short wave intra-seasonal modes in the tropical coupled system. It is argued that due to its long wavelength, the low frequency mode would behave like a linear oscillator while the higher frequency short wave modes would be nonlinear. The conceptual model envisages that an interaction between the low frequency linear oscillator and the high frequency nonlinear oscillations results in the observed aperiodicity of the tropical coupled system. This is illustrated by representing the higher frequency intra-seasonal oscillations by a nonlinear low order model which is then coupled to a linear oscillator with a periodicity of four years. The physical mechanism resulting in the aperiodicity in the low frequency oscillations and implications of these results on the predictability of the coupled system are discussed.     

New political violence in Africa – Secular sectarianism in Sierra Leone

Mary Douglas (1993) has indicated some of the shared concerns that keep voluntary enclaves together as ‘social movements’. The present paper describes a rather different kind of enclave politics, being concerned with the ‘new violence’ of groups enclaved by social exclusion and force. The paper focuses on the emergence and subsequent development of dissidents in the civil war in Sierra Leone. The RUF was at the outset a tiny but conventional guerrilla force, modelled on one of the militias in the Liberian civil war, and seeking to overthrow a decayed neo-patrimonial ‘one-party’ regime. Gaining little popular support, its members became marooned in forested isolation on the Liberia-Sierra Leone border. Recruits were mainly school children seized by force and ‘converted’ through having to take part in atrocities against rural civilians. Unable to return to the larger society on pain of summary execution, captives have had little option but to adjust to the political fantasies of a violent and unstable leadership. They were enclaved by force. Indicating the predictive strength of Douglas' arguments about the cultural dynamics of the enclave, the subsequent atrocity-drenched story of the RUF suggests that it is not the content of belief that determines institutional culture but vice versa. To survive, the enforced enclave develops the concerns of the classic ‘sect’ - a doctrinaire ‘rationality’ (expressed in crude acts of ‘subtractive’ violence), rejection of magic, decision making by lots, preoccupation with defection, otiose leadership style. If the rest of the world is to come to terms with violent enclave organizations such as the RUF and Algerian GIA it may have to pay more careful attention to the way enclave institutions think. They may not respond ‘rationally’ to the kinds of incentives offered by mainstream groups organised around hierarchical and/or individualist systems of social accountability. This revised version was published online in August 2006 with corrections to the Cover Date.     

The relationship between intraseasonal tropical variability and ENSO and its modulation at seasonal to decadal timescales

The intraseasonal tropical variability (ITV) patterns in the tropical troposphere are documented using double space-time Fourier analysis. Madden and Julian oscillations (MJO) as well as equatorial coupled waves (Kelvin and Rossby) are investigated based on the NCEP/NCAR Reanalysis data for the 1977–2006 period and the outputs of an intermediate ocean-atmosphere coupled model named LODCA-OTCM. A strong seasonal dependence of the ITV/ENSO relationship is evidenced. The leading relationship for equatorial Rossby waves (with the correlation of the same order than for the MJO) is documented; namely, it is shown that intensification of Rossby waves in the central Pacific during boreal summer precedes by half a year the peak of El Niño. The fact that MJO activity in spring-summer is associated to the strength of subsequent El Niño is confirmed. It is shown that LODCA-QTCM is capable of simulating the convectively coupled equatorial waves in outgoing long wave radiation and zonal wind at 850 hPa fields with skill comparable to other Coupled General Circulation Models. The ITV/ENSO relationship is modulated at low frequency. In particular the periods of low ENSO amplitude are associated with weaker MJO activity and a cancellation of MJO at the ENSO development phase. In opposition, during the decaying phase, MJO signal is strong. The periods of strong ENSO activity are associated with a marked coupling between MJO, Kelvin and equatorially Rossby waves and ENSO; the precursor signal of MJO (Rossby waves) in the western (central) Pacific is obvious. The results provide material for the observed change in ENSO characteristics in recent years and question whether the characteristics of the ITV/ENSO relationship may be sensitive to the observed warming in the central tropical Pacific.     

Nomospace and genospace: A spatial matrix

We are concerned here with the notion of space as a primary condition for building social relations. From this stand, we have created two analytical matrixes that can help us characterize two modes: that of ‘being-there-in-space’ and that of ‘being-of-the-space’; the nomospace and the genospace. While the nomospace is characterized by ‘cold’ connotations, which are ideally defined as a result of a logical option, the genospace is mainly characterized by emotional or ‘warm’ connotations, which originate from a feeling of shared nature and common destiny. We believe that these matrixes could help us to identify the meanings of some behaviours and, therefore, make us more capable of interpreting many dynamics that occur in modern societies. The importance of geography is justified by the existing relationship between these behaviours and their proper spatial form. This revised version was published online in July 2006 with corrections to the Cover Date.     

Hindcast/forecast of ENSO events based upon the redistribution of observed and model dynamic height in the Western Tropical Pacific, 1964–1986

Anomalous sea level, anomalous observed dynamic height (0/400 db) and anomalous model dynamic height are examined at the locations of 13 island sea level stations in the tropical Pacific for each bimonth of the four year period 1979 to 1982. Starting in 1981, the anomalous dynamic height data show off-equatorial Rossby waves propagated toward the W boundary of the Pacific basin. At the W boundary, the model Rossby wave activity was found to have excited coastally trapped Kelvin-Munk waves which transmitted the anomalous dynamic height equatorward. At the equator, coastally trapped wave activity excited eastward propagating equatorial Kelvin waves, yielding a pair of anomalous peaks in dynamic height variability in the E equatorial Pacific associated with the 1982–1983 ENSO event. The evolution of the peaks in dynamic height associated with the Rossby and Kelvin wave activity reflects the redistribution of observed upper-ocean heat content in the W tropical Pacific, providing a qualitative hindcast for the 1982–1983 ENSO event. In consequence of these results, and the results of a related study (Inoue et al. 1985), the redistribution of both observed and model heat content, as evidenced in dynamic height in the W Pacific during the 23-year period 1964–1985, is examined for its ability to hindcast and forecast ENSO events in this period. Complex EOF analysis is applied to the Onset Phase of ENSO events occurring in 1968–69, 1972–73, 1976–77, and 1982–83; it is used to determine the characteristic redistribution of heat content (dynamic height) prior to the Mature Phase of ENSO events. This analysis found both model and observed dynamic height in the N hemisphere to be characterized by wind-driven, westward propagating, baroclinic Rossby wave activity, having a remarkably stable period of 3 years over the 23-year period. The complex time series associated with these first spatial eigen-functions are used to construct observed and model hindcast indices that yield high values one year prior to the Mature Phase of ENSO events of the period. These indices achieve these values due to the incidence upon the Philippine coast in fall/winter of a positive anomaly in dynamic height propagating from the east at nondispersive Rossby long wave speeds.     

Facies characteristics of the basal part of the Talchir Formation,Talchir Basin,India — Depositional history revisited

The lowest unit of the Talchir Formation of Talchir Basin, Orissa, was described by pioneer workers as the ‘basal boulder bed’. In an attempt to explain the co-existence of gravel and clay, materials of contrasting hydraulic properties, a probable situation resembling the effects of the action of ground-ice enabled boulders to be carried down by sluggish currents resulting in an intermixture of large boulders and fine mud was conceived. Misinterpretation of this conclusion led to a general tendency to describe the ‘basal boulder bed’ as ‘glacial tillite’. However, the unit described as ‘basal boulder bed’ is actually represented by a matrix rich conglomerate with pockets of normally graded silty clay. The present study reveals that the depositional imprints preserved in this part of the sedimentary succession indicate emplacement of successive debris flows generated through remobilization of pre-existing unconsolidated sediments. Small pockets of fine-grained turbidites presumably deposited from the entrained turbidity currents associated with the debris flows suggest the composite character of the debris flow deposit.     

Problems associated with tourism development in Southern Africa: The case of Transfrontier Conservation Areas

Tourism in Southern Africa is synonymous with the wildlife safari. In the post-colonial era the establishment of so-called ‘peaceparks’ that straddle the borders of states has come to be seen as a key not only to increasing tourism in the Southern African region, but also to the modernizing of conservation policies and the development of rural economies. This paper focuses on the global and continental presence of transfrontier conservation areas, the link between conservation and tourism development, and the current factors that constrain and influence the realization of an ‘African Dream’ — ‘establishment of the greatest animal kingdom’. The unstable political situation in Zimbabwe and how this negatively affects wildlife conservation and tourism in the Gonarezhou part of the Greater Limpopo Transfrontier Park, serves as a case study. This revised version was published online in August 2006 with corrections to the Cover Date.     

A characterisation of the physical properties of soil and the implications for landslide occurrence on the slopes of Mount Elgon,Eastern Uganda

Soil properties of major landslides that occurred recently on the mid-altitude slopes of Mount Elgon, eastern Uganda were analysed. A mudflow, located at the Kitati protected forest site, and two deep debris flows on the Nametsi and Buwabwala deforested steep slopes (36°–58°) were surveyed. In order to test the hypothesis that ‘soils at the landslide sites are particularly ‘problem soils’ and thus prone to landslides’, the following analyses were undertaken: particle size distribution, Atterberg limits, shear strength and factor of safety (F_s). Soils at the Kitati and Buwabwala sites exhibited expansive potential, owing to clay contents well above 20%. A clay content exceeding 32% was identified at the Nametsi debris flow site implying an extremely high expansive potential of the soil. High liquid limits (LLs) at Kitati (59%) and Buwabwala (53%) meant that the soils qualified as vertisols susceptible to landslides. High plasticity indices (PIs) (averaging 33%) also confirmed the vertic nature of soils at the Nametsi debris flow site. Whereas the value of F _s  < 1 for the Kitati site signifies an inherently unstable slope, Nametsi and Buwabwala are supposedly stable slopes (F _s  > 1). Despite this finding, the stable sites could be described as only conditionally stable because of the interplay of various physical, pedological and anthropogenic factors. The results point to the fact that soils at the landslide sites are inherently ‘problem soils’ where slope failure can occur even without human intervention. Therefore, the hypothesis that soils at three landslide sites are inherently ‘problem soils’ and prone to landslides, is accepted.     

Contesting Chinatown: Place-making and the Emergence of ‘Ethnoburbia’ in Brisbane,Australia

This paper juxtaposes the actual areas of settlement and settlement activities of Chinese migrants in Brisbane’s southern suburbs since the mid-1980s, with the concomitant, ‘government planned’ construction of the city’s Chinatown as an ‘exotic,’ ‘ethnic,’ and ‘cosmopolitan’ landmark. It argues that while the latter, as with Chinatowns in other Australian and world cities, has continued to appropriate the symbols of so-called ‘Chineseness’ to sell the locale to non-Chinese, the former, in recalling the notion of ‘ethnoburbia,’ significantly evinces actual Chinese migrants’ agency and role in place-making. In the process, these migrants have not only established a local, ethnically meaningful environment, but also challenged the still current metonymic Western image of the Chinese as preferring life in ‘ethnic’ urban enclaves that had its origin from early Chinese settlement and fundamentally detached from the lives of other ethnic groups per se. Indeed greater recognition and comprehension of such locales may go a long way to illustrate that many Chinese living in Australia today do not fit the territorial, place-based identity often associated with them in the imagination of mainstream society.     

Comparisons Between Selected Three-Dimensional Yield Criteria Applied to Rock

This article focuses on two broad categories of yield criteria: those based on the Hoek–Brown yield criterion and a range of other widely used criteria. The first group of criteria source their input data from uniaxial compressive strength, coupled with mineralogical and structural properties of the rock. The second group of selected criteria, here referred to as ‘frictional criteria’, source their input data from one or more of the parameters uniaxial compressive strength, cohesion and friction. Although some authors have attempted to compare the predictions of the wide range of published criteria, the results have not been entirely satisfactory due to disparities in the input data and the difficulties in extrapolating a two-dimensional criterion into three-dimensions. This article presents a strategy for achieving a consistent basis for comparing three-dimensional yield criteria for rock. This strategy is based on using the two-dimensional Hoek–Brown criterion as a single ‘front end’ for calculating the input parameters for the selected frictional criteria. In essence, four amended yield criteria have been defined: the Hoek–Brown–Drucker–Prager (which is a close approximation to the comprehensive Priest criterion); the Hoek–Brown-Coulomb; the Hoek–Brown-modified Wiebols and Cook; and the Hoek–Brown-modified Lade. The predictions of these criteria, and also the comprehensive Zhang-Zhu criterion, can be approximated over a limited range of intermediate principal stress by selecting a value for the weighting factor w between 0.2 and 0.5 in the simplified Priest criterion to achieve the appropriate sensitivity to the intermediate effective principal stress.     

Primitivism and the other. History of art and cultural geography

The article advocates an articulation of cultural geography and art history, and in this perspective focuses on the analysis of the primitivist movement and particularly on Gauguin's work and personal itinerary. Primitivism introduced artefacts of ‘primitive’ people into the history of Western art and signalled a change in the relationship between the West and the ‘Other’ and ‘Elsewhere’. This reversal of values has a major geographical dimension. Primitivism manifests the contradiction-rife colonial ideology, but can also challenge colonization. Tourism, which is, in the case of Tahiti, directly linked to Gauguin and to his myth, inherited a lot from primitivism, in terms of hopes and ambiguities. Conversely, primitivism casts light on geographical features of these places, instituted as ‘Elsewheres‘ by the West, and visited, even transformed by painters, colonizers and tourists. This revised version was published online in July 2006 with corrections to the Cover Date.     

Surviving in the periphery of the town — the living conditions of sahelian drought refugees in Mopti (Republic of Mali)

This article intends to describe the social situation and living conditions of the drought refugees living in the periphery of Mopti. The complex phenomenon of ‘poverty’ and of social discrimination is explained by different indicators (kind of ‘informal economy’, kind of dwelling, composition of food, hygienic situation). In contemporary Africa hunger has become a problem of those people who have lost their original social and economic roots. This holds expecially true for the drought refugees. The transformation of nomads and peasants into proletarian and dependent outcasts will be demonstrated.     

The local politics of the global countryside: boosterism,aspirational ruralism and the contested reconstitution of Queenstown,New Zealand

This paper examines the local politics through which the reconstitution of rural localities under globalization is advanced and contested, with particular reference to the impact of international amenity migration. It contends that as globalization proceeds not by domination but by hybridization and negotiation, local politics is critical as the sphere in which the outcomes of globalization processes are interpreted and contested. The paper examines the case study of Queenstown Lakes district in South Island, New Zealand, as a locality that has experienced significant transformation through engagement with globalization processes. These include high levels of international amenity in-migration, substantial overseas investment in property, commerce and construction projects, and an increasing volume of international tourists. Collectively, these processes have contributed to rapid population growth and intensive pressure for the development of rural land in the area. As detailed in the paper, land use planning became the dominant issue in local politics, with conflict between groups informed by ‘boosterist’ and ‘environmentalist’ stand-points, as well as the ‘aspirational ruralism’ of amenity in-migrants. Although locally-grounded, the conflict engaged trans-local actors and networks and transgressed space and scale, thus becoming itself an expression of globalization.     

Key barriers to community cohesion: views from residents of 20 London deprived neighbourhoods

The notion of community has been central to the political project of renewal of New Labour in the UK. The paper explores how the discourses of community are framed within New Labour and discusses these in the light of the results from research which focuses on how people within urban deprived areas construct their community. It draws upon the results of one part of a larger research project (the ‘Well London’ programme) which aimed to capture the views of residents from 20 disadvantaged neighbourhoods throughout London using an innovative qualitative method known as the ‘World Café’. Our results show the centrality of young people to the development of cohesive communities, the importance of building informal relationships between residents alongside encouraging greater participation to policy making, and the need to see these places as fragile and temporary locations but with considerable social strengths. Government policies are only partially addressing these issues. They pay greater attention to formally encouraging citizens to become more involved in policy making, largely ignore the contribution young people could make to the community cohesion agenda, and weakly define the shared norms and values that are crucial in building cohesive communities. Thus, the conclusion is that whilst an emphasis of the government on ‘community’ is to be welcome, more needs to be done in terms of considering the ‘voices’ of the community as well as enabling communities to determine and act upon their priorities.     

A comparative analysis of several vulnerability concepts

A comparative analysis of six vulnerability models aims to identify differences and similarities between several approaches towards understanding vulnerability. The analysis yields a set of characteristics for explaining the condition of vulnerability (multiple contexts, multiple dimensions, temporal variability, multiple scales and scale-interdependency). In addition, ‘adaptation’ and ‘adaptive capacity’ are identified as key elements of vulnerability. The results of the analysis are put into a wider context not only of vulnerability but also of resilience and risk research. It is demonstrated that ‘adaptation’ and ‘adaptive capacity’ serve as hinges not only for conceptualising vulnerability but between ‘vulnerability’ and ‘resilience’ alike. Based on the results of the comparative analysis, a model of vulnerability focussing on the household and community scale is developed, which displays the key findings of this work.     

Pathways,motivations and challenges: contemporary Tuvaluan migration to New Zealand

The global climate change literature suggests that at some point in the future it is possible that low-lying areas may be drowned due to rising sea levels, and a number of Pacific Ocean states could be particularly vulnerable. It is increasingly evident that the emerging scenario of environmental change has compounded more established push–pull factors leading to migration, and has provided a new imperative for migration decision-making. By interrogating the proposition that there is a clear distinction between the policy categories of ‘migrants’ and ‘refugees,’ we examine a hitherto un-defined group of Tuvaluan migrants whose movement is in response to environmental change and possible climate change effects. The paper examines Tuvaluan migration to New Zealand through various immigration schemes for permanent residency, with an emphasis on the International/Humanitarian stream.