The meteorology of the Western Indian Ocean, and the influence of the east African highlands

This paper reviews the meteorology of the Western Indian Ocean and uses a state–of–the–art atmospheric general circulation model to investigate the influence of the East African Highlands on the climate of the Indian Ocean and its surrounding regions. The new 44–year re–analysis produced by the European Centre for Medium range Weather Forecasts (ECMWF) has been used to construct a new climatology of the Western Indian Ocean. A brief overview of the seasonal cycle of the Western Indian Ocean is presented which emphasizes the importance of the geography of the Indian Ocean basin for controlling the meteorology of the Western Indian Ocean. The principal modes of inter–annual variability are described, associated with El Niño and the Indian Ocean Dipole or Zonal Mode, and the basic characteristics of the subseasonal weather over the Western Indian Ocean are presented, including new statistics on cyclone tracks derived from the ECMWF re–analyses. Sensitivity experiments, in which the orographic effects of East Africa are removed, have shown that the East African Highlands, although not very high, play a significant role in the climate of Africa, India and Southeast Asia, and in the heat, salinity and momentum forcing of the Western Indian Ocean. The hydrological cycle over Africa is systematically enhanced in all seasons by the presence of the East African Highlands, and during the Asian summer monsoon there is a major redistribution of the rainfall across India and Southeast Asia. The implied impact of the East African Highlands on the ocean is substantial. The East African Highlands systematically freshen the tropical Indian Ocean, and act to focus the monsoon winds along the coast, leading to greater upwelling and cooler sea–surface temperatures.

Good governance and the extractive industries in sub-saharan Africa

This article critically examines the challenges that come with implementing the Extractive Industries Transparency Initiative (EITI)a policy mechanism marketed by donors and Western governments as a key to facilitating economic improvement in resource-rich developing countriesin sub-Saharan Africa. The forces behind the EITI contest that impoverished institutions, the embezzlement of petroleum and/or mineral revenues, and a lack of transparency are the chief reasons why resource-rich sub-Saharan Africa is underperforming economically, and that implementation of the EITI, with its foundation of good governance, will help address these problems. The position here, however, is that the task is by no means straightforward: that the EITI is not necessarily a blueprint for facilitating good governance in the region's resource-rich countries. It is concluded that the EITI is a policy mechanism that could prove to be effective with significant institutional change in host African countries but, on its own, it is incapable of reducing corruption and mobilizing citizens to hold government officials accountable for hoarding profits from extractive industry operations.

The genus Borassus (Arecaceae) in West Africa, with a description of a new species from Burkina Faso

Borassus akeassii Bayton, Ouedraogo & Guinko sp. nov. (Arecaceae) is described as a new species from western Burkina Faso in West Africa. It has been confused with the widely distributed African species B. aethiopum and more recently with the Asian B. flabellifer. However, it is distinguished by its glaucous, green leaves with weakly armed petioles and a characteristic pattern of lamina venation. The fruits have a pointed apex and are greenish when ripe, and the flowers of the pistillate inflorescence are arranged in three spirals. The pollen has a reticulate tectum and distinctive ornamentation. The distribution of B. akeassii is discussed and the status of the varieties of Borassus aethiopum (var. bagamojensis and var. senegalensis) is examined. (c) 2006 The Linnean Society of London.

Chemical and aerosol characterisation of the troposphere over West Africa during the monsoon period as part of AMMA

During June, July and August 2006 five aircraft took part in a campaign over West Africa to observe the aerosol content and chemical composition of the troposphere and lower stratosphere as part of the African Monsoon Multidisciplinary Analysis (AMMA) project. These are the first such measurements in this region during the monsoon period. In addition to providing an overview of the tropospheric composition, this paper provides a description of the measurement strategy (flights performed, instrumental payloads, wing-tip to wing-tip comparisons) and points to some of the important findings discussed in more detail in other papers in this special issue. The ozone data exhibits an "S" shaped vertical profile which appears to result from significant losses in the lower troposphere due to rapid deposition to forested areas and photochemical destruction in the moist monsoon air, and convective uplift of ozone-poor air to the upper troposphere. This profile is disturbed, particularly in the south of the region, by the intrusions in the lower and middle troposphere of air from the southern hemisphere impacted by biomass burning. Comparisons with longer term data sets suggest the impact of these intrusions on West Africa in 2006 was greater than in other recent wet seasons. There is evidence for net photochemical production of ozone in these biomass burning plumes as well as in urban plumes, in particular that from Lagos, convective outflow in the upper troposphere and in boundary layer air affected by nitrogen oxide emissions from recently wetted soils. This latter effect, along with enhanced deposition to the forested areas, contributes to a latitudinal gradient of ozone in the lower troposphere. Biogenic volatile organic compounds are also important in defining the composition both for the boundary layer and upper tropospheric convective outflow. Mineral dust was found to be the most abundant and ubiquitous aerosol type in the atmosphere over Western Africa. Data collected within AMMA indicate that injection of dust to altitudes favourable for long-range transport (i.e. in the upper Sahelian planetary boundary layer) can occur behind the leading edge of mesoscale convective system (MCS) cold-pools. Research within AMMA also provides the first estimates of secondary organic aerosols across the West African Sahel and have shown that organic mass loadings vary between 0 and 2 μg m−3 with a median concentration of 1.07 μg m−3. The vertical distribution of nucleation mode particle concentrations reveals that significant and fairly strong particle formation events did occur for a considerable fraction of measurement time above 8 km (and only there). Very low concentrations were observed in general in the fresh outflow of active MCSs, likely as the result of efficient wet removal of aerosol particles due to heavy precipitation inside the convective cells of the MCSs. This wet removal initially affects all particle size ranges as clearly shown by all measurements in the vicinity of MCSs.

Considering heteroglossia in language and development in Sub-Saharan Africa

Countries throughout the sub-Saharan (SSA) region have a complex linguistic heritage having their origins in opportunistic boundary changes effected by Western colonial powers at the Berlin Conference 1884-85. Postcolonial language-in-education policies valorizing ex-colonial languages have contributed at least in part to underachievement in education and thus the underdevelopment of human resources in SSA countries. This situation is not likely to improve whilst unresolved questions concerning the choice of language(s) that would best support social and economic development remain. Whilst policy attempts to develop local languages have been discussed within the framework of the African Union, and some countries have experimented with models of multilingual education during the past decade, the goalposts have already changed as a result of migration and trade. This paper argues that language policy makers need to be cognizant of changing language ecologies and their relationship with emerging linguistic and economic markets. The concept of language, within such a framework, has to be viewed in relation to the multiplicity of language markets within the shifting landscapes of people, culture, economics and the geo-politics of the 21st Century. Whilst, on the one hand, this refers to the hegemony of dominant powerful languages and the social relations of disempowerment, on the other hand, it also refers to existing and evolving social spaces and local language capabilities and choices. Within this framework the article argues that socially constructed dominant macro language markets need to be viewed also in relation to other, self-defined, community meso- and individual micro- language markets and their possibilities for social, economic and political development. It is through pursuing this argument that this article assesses the validity of Omoniyi’s argument in this volume, for the need to focus on the concept of language capital within multilingual contexts in the SSA region as compared to Bourdieu’s concept of linguistic capital.  

Isotype in Africa, 1952–58

A review of work done by the Isotype Institute in the 1940s and 1950s, associated with Africa. The chapter discusses Otto Neurath's growing interest in the last years of his life in the issue of presenting information to (West) Africans through Isotype methods. Although this interest was not realised by Otto Neurath in the form of completed work during his lifetime, Marie Neurath and the Isotype Institute did successfully carry out numerous projects in Britain's West African colonies during the 1950s, in Sierra Leone, Gold Coast (Ghana), and most extensively in the Western Region of Nigeria. Discussion of these projects illustrates the means by which Isotype work was carried out in a developing world context, the difficulties that were encountered, and the issues of effectiveness and sustainability the work raised.

Keine romantische liebe in Africa? Mission, Manner, Monogamie

The sparse historical and anthropological research on romantic love in Africa south of the Sahara gives the impression that the phenomenon may merely be of marginal importance. Instead, the reasons for the apparent impossibility to write about love in Africa are largely rooted in its epistemology: Western stereotypes of a continent inhabited by tribal, atavistic people, barely modernised by colonialism or touched by globalisation which introduced romantic love to the world region have been in part responsible for this dearth of academic knowledge, as have recent identity politics and practical concerns that focused research in the area on sexuality. Here, the main argument is that the almost complete silence about love in Africa may be addressed by applying a more inclusive concept of love that embraces ideologies and practices hitherto neglected, such as polygyny, and that expands the one which has been developed by historians of the medieval and early modern periods. This, in turn, enriches the research on the history of love in Western societies.

Simulated changes in the relationship between tropical ocean temperatures and the western African monsoon during the mid-Holocene

Results from nine coupled ocean-atmosphere simulations have been used to investigate changes in the relationship between the variability of monsoon precipitation over western Africa and tropical sea surface temperatures (SSTs) between the mid-Holocene and the present day. Although the influence of tropical SSTs on the African monsoon is generally overestimated in the control simulations, the models reproduce aspects of the observed modes of variability. Thus, most models reproduce the observed negative correlation between western Sahelian precipitation and SST anomalies in the eastern tropical Pacific, and many of them capture the positive correlation between SST anomalies in the eastern tropical Atlantic and precipitation over the Guinea coastal region. Although the response of individual model to the change in orbital forcing between 6 ka and present differs somewhat, eight of the models show that the strength of the teleconnection between SSTs in the eastern tropical Pacific and Sahelian precipitation is weaker in the mid-Holocene. Some of the models imply that this weakening was associated with a shift towards longer time periods (from 3–5 years in the control simulations toward 4–10 years in the mid-Holocene simulations). The simulated reduction in the teleconnection between eastern tropical Pacific SSTs and Sahelian precipitation appears to be primarily related to a reduction in the atmospheric circulation bridge between the Pacific and West Africa but, depending on the model, other mechanisms such as increased importance of other modes of tropical ocean variability or increased local recycling of monsoonal precipitation can also play a role.

Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa.

BIOME 6000 is an international project to map vegetation globally at mid-Holocene (6000 14C yr bp) and last glacial maximum (LGM, 18,000 14C yr bp), with a view to evaluating coupled climate-biosphere model results. Primary palaeoecological data are assigned to biomes using an explicit algorithm based on plant functional types. This paper introduces the second Special Feature on BIOME 6000. Site-based global biome maps are shown with data from North America, Eurasia (except South and Southeast Asia) and Africa at both time periods. A map based on surface samples shows the method’s skill in reconstructing present-day biomes. Cold and dry conditions at LGM favoured extensive tundra and steppe. These biomes intergraded in northern Eurasia. Northern hemisphere forest biomes were displaced southward. Boreal evergreen forests (taiga) and temperate deciduous forests were fragmented, while European and East Asian steppes were greatly extended. Tropical moist forests (i.e. tropical rain forest and tropical seasonal forest) in Africa were reduced. In south-western North America, desert and steppe were replaced by open conifer woodland, opposite to the general arid trend but consistent with modelled southward displacement of the jet stream. The Arctic forest limit was shifted slighly north at 6000 14C yr bp in some sectors, but not in all. Northern temperate forest zones were generally shifted greater distances north. Warmer winters as well as summers in several regions are required to explain these shifts. Temperate deciduous forests in Europe were greatly extended, into the Mediterranean region as well as to the north. Steppe encroached on forest biomes in interior North America, but not in central Asia. Enhanced monsoons extended forest biomes in China inland and Sahelian vegetation into the Sahara while the African tropical rain forest was also reduced, consistent with a modelled northward shift of the ITCZ and a more seasonal climate in the equatorial zone. Palaeobiome maps show the outcome of separate, independent migrations of plant taxa in response to climate change. The average composition of biomes at LGM was often markedly different from today. Refugia for the temperate deciduous and tropical rain forest biomes may have existed offshore at LGM, but their characteristic taxa also persisted as components of other biomes. Examples include temperate deciduous trees that survived in cool mixed forest in eastern Europe, and tropical evergreen trees that survived in tropical seasonal forest in Africa. The sequence of biome shifts during a glacial-interglacial cycle may help account for some disjunct distributions of plant taxa. For example, the now-arid Saharan mountains may have linked Mediterranean and African tropical montane floras during enhanced monsoon regimes. Major changes in physical land-surface conditions, shown by the palaeobiome data, have implications for the global climate. The data can be used directly to evaluate the output of coupled atmosphere-biosphere models. The data could also be objectively generalized to yield realistic gridded land-surface maps, for use in sensitivity experiments with atmospheric models. Recent analyses of vegetation-climate feedbacks have focused on the hypothesized positive feedback effects of climate-induced vegetation changes in the Sahara/Sahel region and the Arctic during the mid-Holocene. However, a far wider spectrum of interactions potentially exists and could be investigated, using these data, both for 6000 14C yr bp and for the LGM.

Simulated climate and biomes of Africa during the Late Quaternary: comparison with pollen and lake status data

New compilations of African pollen and lake data are compared with climate (CCM1, NCAR, Boulder) and vegetation (BIOME 1.2, GSG, Lund) simulations for the last glacial maximum (LGM) and early to mid-Holocene (EMH). The simulated LGM climate was ca 4°C colder and drier than present, with maximum reduction in precipitation in semi-arid regions. Biome simulations show lowering of montane vegetation belts and expansion of southern xerophytic associations, but no change in the distribution of deserts and tropical rain forests. The lakes show LGM conditions similar or drier than present throughout northern and tropical Africa. Pollen data indicate lowering of montane vegetation belts, the stability of the Sahara, and a reduction of rain forest. The paleoenvironmental data are consistent with the simulated changes in temperature and moisture budgets, although they suggest the climate model underestimates equatorial aridity. EMH simulations show temperatures slightly less than present and increased monsoonal precipitation in the eastern Sahara and East Africa. Biome simulations show an upward shift of montane vegetation belts, fragmentation of xerophytic vegetation in southern Africa, and a major northward shift of the southern margin of the eastern Sahara. The lakes indicate conditions wetter than present across northern Africa. Pollen data show an upward shift of the montane forests, the northward shift of the southern margin of the Sahara, and a major extension of tropical rain forest. The lake and pollen data confirm monsoon expansion in eastern Africa, but the climate model fails to simulate the wet conditions in western Africa.