Search

The Sahara Desert is the largest source of dust on Earth, and has a significant impact on global atmospheric changes. Wind is the main dynamic factor controlling the transport and intensity of dust in the Sahara Desert. This study comprehensively analyzed the spatial and temporal variation in the wind regime of the Sahara Desert from 1980 to 2019 using data from 17 meteorological stations to improve awareness of global atmospheric changes and the intensity of regional aeolian activities. All wind speed parameters decreased from northwest to southeast. While there were significant differences in the trends of temporal variation in wind speed among the different regions, there was an overall decreasing trend across the Sahara Desert, with an average wind speed of 0.09 m s−1 10 a−1. This decrease was closely related to wind frequency. The easterly, westerly, and northerly winds dominated, with more complex wind direction in the northern region. Seasonal differences in wind direction were observed in all regions. The wind direction frequency of wind speeds >6 m s−1 exceeded those with wind speeds −1 in the western and northern regions, whereas other regions showed an opposite pattern. The highest drift potential (DP) and resultant drift potential (RDP) were found in the western and northern regions, and during spring and winter. There was a trend of decreasing annual variation in DP and RDP in all regions. The directional variability (RDP/DP) indicated mostly intermediate and high variability in wind direction. Resultant drift direction (RDD) indicated that a mainly southwest wind direction. No apparent trends in temporal variation in RDD and RDP/DP were observed. Total DP was strongly influenced by DP and the magnitude and frequency of strong winds in the prevailing wind direction. No strong correlation between wind regimes and dune types was observed in this desert, indicating the complexity of factors affecting dune morphology.

The Napoleonic campaigns paved the way for French metropolitan travellers, military officers and literary authors to roam the barren stretches of North African deserts. Initially, imperial expansion was what brought French explorers to these lands. As devoted adventurers, they were quick to predict the literary opportunities of showcasing emptiness in military, scientific and literary projections. At once empty and loaded with spiritual charge, the desert embodies the essence of mystical connotations, for those who master decrypting its unsettling silence. This article argues that this seemingly empty space is in fact the cradle of spiritual pursuits, deployed in Sèbe’s ‘Saharomania’ concept as a redemptive locus. Showcasing emptiness thus represented a challenge to the spread of the cult of Western materialism. This is illustrated in two ways: the vision of French authors (Saint-Exupéry, Ernest Psichari, Charles de Foucauld, and Eric-Emmanuel Schmitt) who, taken together, amount to the establishment of a French desert genealogy of ‘Saharomania’, and the ways in which it offers a different reading of the accompanying Orientalist understanding of such works, through the prism of the redemptive wisdom of the desert. While taking part in Said’s Western canon on the Orient, redemptive ‘Saharomania’ also participates in the wider definition of the ways in which the imaginary of emptiness fuelled the fin-de-siècle cult of the void. It is in light of the alterity of the desert that the concept of ‘Saharomania’, specific to France, can be read: because showcasing emptiness meant empowerment, the success of the inscription of bareness in the imaginary of the French metropolitan public, and also its literary inheritance, was necessary to celebrate the French national sentiment. Taking the demanding crossing of the desert to heart, often for nationalist pursuits, was necessary to triumph over the physically and mentally exhausting desert. However, this article argues, authors incline when faced with the grandeur of the Sahara Desert, and its emblematic nomad dwellers, amidst the journey of the conventional fate of loss in the sands, ultimately changing the initial motives of the crossing. Thus, rather than condemning the present French literary productions within the confines of the orientalist and exotic tropes, this article offers different but no less significant interrogations about how ‘Saharomania’ valorises the desert as a locus of the higher forms of humankind, particularly defying the cult of Western hollowness through articulating spiritual resonance in the realm of the void. Les campagnes napoléoniennes ont ouvert la voie aux voyageurs métropolitains, officiers militaires et romanciers français, partis errer dans les étendues arides des déserts d’Afrique du Nord. Au départ, c’est l’expansion coloniale qui emmena des explorateurs français dans ces contrées. En aventuriers dévoués ils se mirent rapidement à entrevoir les opportunités littéraires d’exposer le vide dans des projections militaires, scientifiques et romanesques. À la fois vide et chargé de spiritualité, le désert incarne l’essence du mysticisme, pour ceux qui parviennent à décrypter son troublant silence. Cet article développe l’idée selon laquelle ce qui semble être un espace vide, est en fait un berceau de quêtes spirituelles, au cœur du concept de « Saharomanie » élaboré par Berny Sèbe comme un lieu de rédemption. Ainsi, l’exposition du vide représentait un défi à la diffusion du culte du matérialisme occidental. Deux dimensions viennent l’illustrer : la vision d’auteurs français (Saint-Exupéry, Ernest Psichari, Charles de Foucauld, et Eric-Emmanuel Schmitt) qui, ensemble, constituent une généalogie de la « Saharomanie » française du désert, et la relecture de la compréhension orientaliste de ces travaux, à travers le prisme de la sagesse rédemptrice du désert. Tout en participant au canon occidental sur l’Orient défini par Saïd, la « Saharomanie » rédemptrice participe aussi à une plus large définition des canaux empruntés par l’imaginaire du vide pour alimenter le culte de l’absence caractéristique de la fin de siècle. C’est à la lumière de l’altérité du désert que le concept de « Saharomanie », particulier à la France, peut être lu : parce que l’exposition du vide s’accompagnait d’un certain sentiment de pouvoir, le succès de l’inscription de la sécheresse dans l’imaginaire du public français métropolitain, ainsi que son héritage littéraire, fut nécessaire à la célébration du sentiment national français. Prendre à cœur l’exigeante traversée du désert, souvent pour des motifs nationalistes, était indispensable pour triompher de l’immensité de sable qui épuisait aussi bien physiquement que mentalement. Toutefois, cet article développe l’idée selon laquelle les auteurs s’inclinent devant la grandeur du désert du Sahara, et ses emblématiques habitants nomades, dans le voyage du destin conventionnel de la perte dans les sables, finissant par changer les motifs initiaux de la traversée. Ainsi, plutôt que de condamner ces productions littéraires françaises en les confinant à des tropes exotiques et orientalistes, cet article propose des interrogations différentes, mais non moins significatives, en montrant comment la « Saharomanie » valorise le désert comme un lieu où se trouvent des formes plus évoluées de l’humanité, défiant particulièrement le culte de la vacuité occidentale dans l’articulation des résonances spirituelles du royaume du vide.

International audience; This study highlights the occurrence of atmospheric rivers (ARs) over northwest Africa towards Europe, which were accompanied by intense episodes of Saharan dust transport all the way to Scandinavia, in the winter season. Using a combination of observational and reanalysis data, we investigate two extreme dusty AR events in February 2021 and assess their impact on snow melt in the Alps. The warm, moist, and dusty air mass (spatially-averaged 2-meter temperature and water vapour mixing ratio anomalies of up to 8 K and 3 g kg-1, and aerosol optical depths and dust loadings of up to 0.85 and 11 g m-2, respectively) led to a 50% and 40% decrease in snow depth and surface albedo, respectively, in less than one month during the winter season. ARs over northwest Africa show increasing trends over the past 4 decades, with 78% of AR events associated with severe dust episodes over Europe.

В статье научно описаны один из основных факторов окружающей среды для роста, размножения, развития и распространения организмов на Земле., The article scientifically describes one of the main environmental factors for the growth, reproduction, development and spread of organisms on Earth.

Since the early 2000s, the genus Buthus Leach, 1815 (family Buthidae) has been the subject of an important number of studies. These concerned particularly the species belonging to the ‘Buthus occitanus’ complex. A number of populations previously considered as subspecies or varieties of B. occitanus Leach were raised to the rank of species, but also many new species have been described. Most of the species considered in these studies come from North Africa, in particular from Morocco, Mauritania, Chad, Sudan and Egypt, but only two new species were recorded from Algeria. At present, one more new species of Buthus is described from the Algerian Saharan Desert, raising the number of confirmed Buthus in Algeria to five. Since most Buthus species from North Africa, and in particular those from Algeria, inhabit more mesic environments than the Saharan Central compartment, the new species appears as the first true deserticolous species found in this country.

Due to its location on West Coast of Africa, Cape Verde is highly influenced by Sahara Desert dust events being an optimum place to observe and study the African aeolian aerosol. During 2011, particulate matter with an aerodynamic diameter lower than 10 μm (PM10) was sampled in Santiago Island and its chemical composition was evaluated by k 0-instrumental neutron activation analysis (k 0-INAA) and particle induced X-ray emission (PIXE). This study showed the existence of a seasonal intrusion of dust from Africa (that occurred from October to March) characterized by significant increases of PM10, mineral elements and anthropogenic particles concentrations. In 2011, the PM10 health-based air quality guidelines defined by WHO, EU and USEPA were exceeded. Cape Verde PM10 composition was characterized essentially by high concentrations of elements originating from the soil (Ca, Ce, Co, Fe, K, Mg, Mn, Rb, S, Sc, Si, Sm, and Ti) and sea (Br, Cl, and Na); and low concentrations of anthropogenic elements (As, Cr, Cu, Ni, Pb, Sb, V, and Zn). k 0-INAA and PIXE were fundamental tools for the determination of airborne chemical elements in Cape Verde. Their multi-elemental capabilities in association with low detection limits made it possible to determine the majority of the element concentrations of environmental interest.

The eastern part of the Sahara is at present the driest region of the desert. Yet the extensive animal rock art in the area, presumed to depict real activities in the lives of the painters, suggests that environmental conditions were significantly different when the rock art was produced. Here we report on exploration of the area, which led to the discovery of morphologically-distinct carbonate structures that line the walls of two valleys in Gebel Uweinat, and were likely formed in standing water. The carbonate structures comprise what appear to be shoreline carbonate formations, and date back to 8100 and 9400 years BP. The chemical and morphological similarity of these formations to carbonate structures from modern lakes suggests that these lakes contained fresh, standing water suitable for human and animal use. However, the significant quartz content suggests that windblown sand was pervasive, and thus the vegetation cover may have been sparse. This discovery supports the possibility of grasslands in the area, which may have been able to support human habitation, and adds to the evidence for a wetter climate in the area in the early Holocene., Journal of African Earth Sciences, 89, ISSN:1464-343X, ISSN:0731-7247, ISSN:0899-5362, ISSN:1879-1956

A cross-sectional survey among Saharawi refugees in four camps carried out in 2007 revealed enlarged thyroid volume and high urinary iodine concentration in women and school children. The purpose of this paper is to describe the content of iodine in food and water and explore whether any sources in the environment can explain the situation. Samples of water ( n = 143), milk ( n = 19) and salt ( n = 89) were collected. Different wells supplied the camps with water and the median iodine concentration was 108 μg/L (range 55–545 μg/L) and significantly higher in two of the camps (El Aiune and Ausserd; 300 μg/L (range 55–545 μg/L)), compared to the two other camps (Smara; 87 μg/L (55–127 μg/L) and Dakla; 70 μg/L (55–96 μg/L)). In local goat milk the median iodine concentration was 370 μg/L (70–13,070 μg/L). The median content of iodine in salt was 6 μg/g (0–51 μg/g). Water and local milk were the most important sources of iodine for women. High levels of iodine in water seem to be one of the main sources of iodine that affects humans as well as animals.

The authors find a context for the rock art of the central Sahara by excavating and recording examples of engraved stones from circular platforms used to sacrifice animals. The type of rock art known as the Pastoral style, featuring evocative outline drawings of cattle, appears on upright stones incorporated into the platforms in the period 5430–5150 BP, and probably earlier. Furthermore, they show that these places were part of a dense and extensive monumental landscape, occupying a harsh environment, supplying quartzite, but with little settlement, appearing to serve the spiritual needs of hundreds of Neolithic people.

The climatic changes that have taken place in North Africa since the Tertiary have had a profound influence on the composition of the flora and fauna, and the present day distribution patterns of the Tenebrionidae are based on both historical and recent ecological processes. In order to explain these patterns, the intensity of the investigations and the state of taxonomic knowledge must be known. These two parameters are the subject of this paper. An example is given of a distribution pattern (taxa in the marginal areas of the Red Sea) as well as of a faunal divide and a migration road (the River Nile as a faunal divide and a migration road)., Les changements climatiques qui sont intervenus en Afrique du nord depuis le Tertiaire ont eu une influence profonde sur la composition de la flore et de la faune, et les modèles actuels de distribution des Tenebrionidae sont basés sur des processus écologiques et historiques récents. Afin d'expliquer ces modèles, l'intensité des investigations et l'état de la connaissance taxonomique doivent être connus. Ces deux paramètres sont le sujet de cet article. Il y a un grand nombre de types de répartition des Coléoptères Ténébrionides au Sahara. Un exemple est décrit : les taxa des côtes de la mer Rouge. En outre une frontière faunistique et une route de migration (le Nil a les deux fonctions) sont présentées., Lillig Martin. Distribution patterns in the Tenebrionidae of the Sahara Desert (Insecta : Coleoptera). In: Cahiers scientifiques du Muséum d'histoire naturelle de Lyon - Centre de conservation et d'étude des collections, tome 10, 2006. pp. 133-137.

For the first time, ambient levels of benzene, toluene, carbon tetrachloride and selected oxygenated organic compounds have been measured in both populated and remote sites in the Sahara desert. The levels of these species were generally found to be high in the industrialized regions of the North Sahara, progressively decreasing with latitude so that lowest levels were reached in remote desert sites close to the Equator. The emissions from traffic, and the oil production and its transformation, together with the solvent use were the main anthropogenic sources determining the levels of aromatic, aliphatic and chlorinated organic compounds in desert sites near two Algerian cities. Substantial levels of acetone and some semi-volatile compounds, emitted or formed by photochemical reactions, were also found. Although some of these compounds were below the detection limits in the most remote sites of the Sahara desert located in Mauritania and Niger, measurable levels of benzene and toluene were still found together with significant amounts of acetone. Data seem to indicate that forest fires occurring in the tropical regions of the North African continent were the most likely sources for the background levels measured during most of our measurements. The data presented here did not differ too much from those measured in the most isolated sites of the northern hemisphere.

During the migratory period, birds are confronted with many physiological challenges that may change dramatically in short succession. Flight phases with voluntary anorexia and simultaneous high metabolic turnover for flight are interrupted by stopover phases with intense foraging behaviour and high intake and processing of food. Functionally, the digestive system plays the important role during stopover and becomes irrelevant during flight. On the other hand, exercise organs have an inverse role, being highly active during flight but much less so during stopover. In the course of migration, these temporary functional differences are reflected in phenotypic organ changes (Piersma and Lindstrom 1997; Biebach 1998; Mc Williams and Karasov 2001). Several hypotheses have been put forward to explain the costs and benefits of this functional and structural flexibility, some of which are not mutually exclusive (Bauchinger and Biebach 1998). Here, we present data on structural changes in the digestive system, the leg muscles, the liver and the exercise organs — such as the flight and heart muscles — of garden warblers (Sylvia borin) during the long flight across the Sahara desert within one season during spring 1998. The benefits of these structural adjustments are estimated quantitatively with respect to the energetic savings during flight.