This work was supported in part by a grant from the National Science Foundation, No. This includes the upper-level circulation as well as the Saharan Heat Low. Within the core of the deep cell lies a deep region of moist air in which relative humidity is 60–80% throughout the troposphere. Thus, most of the central Sahara has, on average, a second peak in one of the transition season months. Figure 16. This climate is considered to be BSh according to the Köppen-Geiger climate classification. The picture is very different in July when a thermal low exists over the northwestern Sahara, between the Hoggar and the Atlas Mountains. Thus, the drier the region, the greater the interannual variability of rainfall. Explores some of the United States most severe or unusual weather systems, including electrified dust storms, pink snowstorms, luminous tornadoes, ball lightning, and falls of fish and toads. Research during the last decade has greatly modified the picture just described and the current paradigm is that of a monsoon system. Mean annual rainfall steadily increases southward toward the equator, but nearly everywhere it is less than 2,000 mm. A second region of low pressure exists in the eastern Sahara and over the Arabian Peninsula. Bring bug repellant, light raingear, easy-dry clothes, and appropriate rain footwear, like sturdy sandals. These can persist for days on end (Nicholson, 1981). Along this gradient, the vegetation becomes increasingly taller and the proportion of woody species (trees, shrubs, bushes) and the amount of ground cover increase. The SAL resides between roughly 900 mb/1,800 m and 500 mb/5,500m near the Atlantic coast (Carlson & Prospero, 1972), but it extends considerably higher over the continent (Parker, Thorncroft, Burton, & Diongue-Niang, 2005). Ultra energy-efficient LED with 50-year lifespan set to hit shelves, Pushing for a progressive approach to climate-forced displacement, The dawn of the digital lighting metropolis, Understanding the impact of climate change on urban water systems in Africa. Dust is transported across the Atlantic and into Europe (Figure 16). The main circulation features are the TEJ in the upper-troposphere and the midlevel AEJ. It arises as the easterlies are channeled through the gap between the Tibesti and Ennedi massifs (Todd, Washington, Raghavan, Lizcano, & Knippertz, 2008; Washington & Todd, 2005). Schematic illustration of the revised picture of the West African monsoon (from Nicholson, 2009). The amount of heat from the sun plays a major role in determining climate. The paper, published recently in the journal Climate Change by researchers working with AMMA-2050, shows that by the end of the century the average day in West Africa will be well outside of what people experience in today’s climate. Figure 10. The southern desert boundary is generally given as 50 mm/year, with no preferred seasonality. Based on an International Workshop held in Geneva in 2005, this book reviews the advances made so far in seasonal climate predictions and their applications for management and decision-making in agriculture. In the second mode, rainfall anomalies are mostly of the same sign through West Africa. Schematic of the rain belt over West Africa (from Nicholson, 2009). Along the coast, the rainfall exceeds 3,000 millimeters (118 inches) per year. In the semi-arid regions cloud cover during the boreal summer rainy season similarly reduces temperature, so that the highest temperatures occur in April or May, just prior to the rainy season. This scenario stems back to the time when rainfall in the tropics was thought to result mainly from local thunderstorms. Marikana Weather In August 2011. The second characteristic is the similarity of the two time series on decadal time scales, with high rainfall in the 1950s and driest conditions in the 1980s. Many countries in Africa experience two rainy seasons: a major rainy season which takes place roughly from April through June, and a shorter rainy season from October through December. For one, these tend to roughly follow the rainfall seasonality. Overall, West Africa is relatively devoid of high terrain (Figure 3). As rainfall increases progressively southward from the Sahara there is a gradual transition between semidesert grassland, savanna grassland with low trees and shrubs, savanna woodland, woodland, and forest. The most important factors are the intensity of the Tropical Easterly Jet, the latitude of the African Easterly Jet, and the intensity of the equatorial westerly flow. Griffiths (1972) provides specifics for numerous stations). The iron-rich soils are often mixed with bare stretches of hard, rocky, and impervious sandstone or laterite (hardpan) crusts (Figure 2). Figure 17 shows before and after photos of a swimming pool in Niamey during a July storm. The belt of westerlies expands with altitude and also exhibits a seasonal displacement towards the summer hemisphere. Throughout West Africa the diurnal range exceeds the annual. This is a likely factor in the decadal scale persistence of rainfall anomalies. Over most of West Africa they are on the order of 21–24 °C. Rainfall in the Sahel is also remarkably persistent from year to year, with rainfall being above the long-term mean every year from 1950 to 1967, then below the mean in every year but one from 1978 to 1986. The third feature, low-level westerly flow near the equator, is apparent throughout the year. This is especially true for equatorial countries like Uganda, Rwanda, Kenya and the Democratic Republic of the Congo, where temperatures remain consistently hot all year round but the amount of precipitation changes dramatically. This is as the region warms and the monsoon rains are disrupted in response to worsening global atmospheric carbon pollution. When someone is badly sleep deprived, their reflexes may be as compromised as if they are intoxicated with alcohol. To emphasize this point, various authors refrain from using the term “ITCZ” with respect to West Africa and make specific mention of the region of high rainfall. rain Weather West Africa, Satellite Weather West Africa, Weather Forecast, Rainfall, Clouds, Sun in West Africa - Source: SAT24.com Minimum temperatures in July, however, show little latitudinal variation. Temperature (T) and dew point temperature (Td) are in ° C. In the classic picture of West African climate, rainfall and its seasonality are associated with the annual displacement of a surface feature, the Intertropical Convergence Zone (ITCZ). The exception is a September peak in the narrow belt in the southernmost sector of the Soudano-Guinean zone. A strong factor in decadal-scale fluctuations appears to be the Atlantic Multidecadal Oscillation (AMO) (Ting, Kushnir, Seager, & Li, 2011; Zhang & Delworth, 2006). A person with a sleep-starved brain may experience depression, irritability, clumsiness, forgetfulness, and, in the long-term, even weight gain. The average annual temperature is 21.1 °C | 70.0 °F in Madikwe Safari Lodge. West Africa is one of the world’s most vulnerable regions to climate variability and change. The name comes from the fact that, viewed from the air, the vegetation clusters resemble stripes on a tiger. Look for fabrics that are light (in color and material) moisture-wicking and quick-drying. This volume reflects the current state of scientific knowledge about natural climate variability on decade-to-century time scales. The current image of the monsoon contrasts with the classic picture of West African climate in the diminished importance of the ITCZ and the inclusion of several jet streams and the Saharan Heat Low. The best known is the Bodélé Jet in northern Chad. Within the Sahara itself it ranges from about 75% to over 150%. The hottest months are December to February. Prosperity was so good that wheat was exported from the Niger Bend region. The dust was fairly localized and transient during the 1950s, but increased steadily as a result of the drought in the early 1970s and early 1980s (N’tchayi Mbourou, Bertrand, & Nicholson, 1997). One is a pattern of opposition between the Sahel and the Guinea Coast, a pattern often referred to as a rainfall dipole. Mean sea-level pressure and mean surface winds in January, April, July, and October, based on ERA 40 data. A boundary layer feature termed the Nocturnal Low-Level Jet (NNLJ) also influences rainfall over the region by way of moisture transport (Abdou, Parker, Brooks, Kalthoff, & Lebel, 2010; Lothon, Said, Lohou, & Campistron, 2008; Sultan, Janicot, & Drobinski, 2007). This may be a result of the strong relationship between the cross-equatorial pressure gradient and Sahel rainfall, as described in section on a “Conceptual Model of Rainfall Variability over the Sahel.” The AMO and this pressure gradient over West Africa are closely linked (Nicholson & Webster, 2007). of Arizona. Found insideThe book also examines the potential for using climate forecasts and ecological observations to help predict infectious disease outbreaks, identifies the necessary components for an epidemic early warning system, and reviews lessons learned ... Aspects of the rainfall regime that are considered include its unique characteristics, its changes over time, the storm systems that produce rainfall, and factors governing its variability on interannual and decadal time scales. The climate crisis - and how we confront it - is THE story of our lifetimes. The IPCC predicts millions of people in Africa will persisten… There is consensus that sea-surface temperatures play the most important role on interannual and longer-term decadal rainfall fluctuations, but there is much less agreement concerning the ocean regions of greatest influence. The intention of this novel approach to framing climate modelling projection for the region is to make the scenarios more real for West African policy makers, by making the climate forecasts more relatable, relative to people’s personal experiences. Water quality and availability have deteriorated in most areas of Africa, particularly due to climate change. By the mid-Holocene, some 5,000 years ago, conditions were much wetter than present and most of the Sahara was a savanna environment. Several features apparent in the zonal winds play a major role in West Africa climate. Along its southern border lies the semi-arid Sahel. This article focuses on the climate of the Sahel, but all of West Africa from the central Sahara southward to the Guinea Coast along the Atlantic will be considered to some extent. Cloud cover in the humid zone tends to range from 50% in the driest months to 80–100% during the wet season. People’s sleep patterns are often disrupted during heatwaves, particularly for those who don’t have air conditioning in their homes. This study presents a hierarchical Bayesian modelling framework for the analysis of malaria versus climate factors in West Africa. Subsidence overrides the shallow region of ascent. Throughout the semi-arid regions of West African rainfall is highly variable from year to year. At Climate Home News, we believe journalism can make a difference. Figure 1. Most of the Sahara receives less than 25 mm per year, with large expanses receiving less than 10 mm. Mean maximum temperatures in January increase equatorward, ranging from roughly 21 °C in the central Sahara to 33 °C in latitudes nearest the equator (Figure 11). In the north, about 80–90% of the rainfall occurs during the wettest quarter of the year; in the south, this figure falls to about 50% (Figure 8). In fact, the climate of Africa is more variable by rainfall amount than by temperatures, … The SAL is bound by subsidence inversions at its top and bottom (Figure 19). The rainy period of April through June is wet and humid, making coastal areas unpleasant. In Liberia, the climate is tropical, hot and humid all year round, with a rainy season from May to October due to the African monsoon, and pretty frequent rains in the other months, except in the short dry season that runs from December to February, which is more marked in the north. In general, soil fertility is low and the soils are often degraded. A Brief Overview of Africa's Dry and Rainy Seasons, The Weather and Climate in Southeast Asia. An important aspect of the climate is the dense dust layer that prevails in much of the region. West Africa has been identified as a climate-change hotspot, with climate change likely to lessen crop yields and production, with resultant impacts on food security. Time your adventure wrong, and you could find yourself caught up in a cyclone during a beach holiday to Madagascar; or stranded by extreme flooding during a cultural trip to the remote valleys of Ethiopia. The plethora of demonstrated relationships with SSTs and the discrepancy between various authors can probably be accounted for by several factors. On average, the Sahel lies within this region of subsidence. Nicholson (2000), Entekhabi (1995), and others suggested that this persistence might be related to land-surface atmosphere feedback. The first is the major shift to dry conditions around 1968, with relatively dry conditions persisting since that time. The resultant rainfall reflects collectively the impact of the world’s ocean, with the dominant factor or factors varying over time. There is little rainfall throughout the year. Figure 15. It's a common mistake to make, but this misconception often causes first-time visitors to ask what the weather's like in Africa, but the reality is, it's impossible to generalize the climate of an entire continent. It includes much of the countries of Mauritania, Senegal, Mali, Niger, Chad, the Sudan, and the northern fringes of Burkina Faso and Nigeria. Rainfall in the Guinea Coast has recovered to some extent in recent years, but the Sahel rainfall has exceeded the long-term mean in only a handful of years. This peak is linked to the northward displacement of the monsoon during the boreal summer. The first of three books in IFPRI's climate change in Africa series, West African Agriculture and Climate Change: A Comprehensive Analysis examines the food security threats facing 11 of the countries that make up West Africa -- Benin, ... Thorncroft et al. Building on the 2012 report, Turn Down the Heat: Why a 4°C Warmer World Must be Avoided, this new scientific analysis examines the likely impacts of present day, 2°C and 4°C warming on agricultural production, water resources, and ... The article commences with a geographical overview followed by a description of the mean climate. Found inside – Page 1991... Africa and the south west Indian Ocean . Climate Dyn . , 15 , 937-951 . Tyson , P. D. , and R. A. Preston - Whyte , 2000 : The Weather and Climate of ... 1738–1756, the 1770s, and the 1790s. Classical picture of the ITCZ over Africa during the boreal summer (from Griffiths, 1972). In some areas there are fluvial or lacustrine soils produced from sediments of former lakes and streams. Nigeria - Nigeria - Climate: Nigeria has a tropical climate with variable rainy and dry seasons, depending on location. Rain is usually abundant during the summer, except for Cape Town. When drought appeared in the Sahel in the late 1960s and early 1970s, Charney (1975) put forth a long-debated hypothesis that the drought was anthropogenic. The diurnal variation of temperature exceeds the annual throughout sub-Saharan West Africa. Figure 29 shows the spatial pattern of rainfall anomalies in these two decades. Northern Africa and the location of the Sahel. Coefficient of variation of annual rainfall (%). Climate and Average Weather in Togo. The vertical motion field associated with this circulation is shown in Figure 23 (Nicholson, 2009). Climate Change and Global Poverty makes concrete recommendations to integrate international development and climate protection strategies. The clusters of dense vegetation can be 200 m in length and 20 m wide. This appears to feed into the ascent of the deep cell. It is strong in April but extremely weak in October. Namibia's climate is that of a hot desert: Not surprisingly, it's dry, sunny, and warm almost year-round. Rain from the stratiform cloud layers typically occurs at night and for a longer period of time, but the rain rate is roughly one-fourth the rain rate associated with convective clouds. A striking characteristic of the West African rainfall regime is the roughly east-west (i.e., zonal) orientation of the rainfall isohyets, as illustrated by both annual and August rainfall (Figure 7). Figure 21. Left: Schematic illustrating the four most common rainfall anomaly patterns over West Africa (from Nicholson, 2008). A study at Niamey, Niger (13.5 °N), in 2006 found that MCSs with squalls accounted for about 90% of the rain there, though the squalls were present in only 17% of rain events (Ferreira, Rickenbach, Guy, & Williams, 2009). Strictly speaking, there are no 'seasons' as such, as temperatures don't vary a great deal throughout the year. Oxford Research Encyclopedia of Climate Science, Climate Impact: Managed Ecosystems and Agriculture, Climate Systems and Climate Dynamics: Biogeochemistry, Climate Systems and Climate Dynamics: Theoretical Foundations, Rainfall Conditions from Historical to Modern Times, A Conceptual Model of Rainfall Variability Over the Sahel, Large-Scale Forcing of Rainfall Variability in the Sahel, https://doi.org/10.1093/acrefore/9780190228620.013.510, Conceptual Model of Rainfall Variability over the Sahel, The impact of decadal-scale Indian Ocean sea surface temperature anomalies on Sahelian rainfall and the North Atlantic Oscillation, Seasonal cycle and interannual variability of the Sahelian rainfall at hydrological scales, Tropical SST and Sahel rainfall: A non-stationary relationship, Changes in the interannual SST-forced signals on West African rainfall: AGCM intercomparison, The West African Sahel: A review of recent studies on the rainfall regime and its interannual variability, Monsoon onset over Sudan-Sahel: Simulation by a regional scale model MM5, Robust features of Atlantic multi-decadal variability and its climate impacts, Climate of Western and Central Equatorial Africa. If you're hoping to save money on a safari, however, rainy season isn't a bad idea. Nicholson and Grist (2003) suggested distinguishing these as the AEJ-N and the AEJ-S. A second feature is an upper-troposphere easterly jet stream, the Tropical Easterly Jet, or TEJ. Most of West Africa, from the southern Sahara to the humid coastal countries, has only one These include the African Monsoon Multidisciplinary Analysis (AMMA) experiment that took place in 2006 (Janicot et al., 2008; Redelsperger et al., 2006); the associated model intercomparisons project (ALMIP) (Boone et al., 2009); the AMMA Catch Experiment, which extended AMMA southward into Benin (Lebel et al., 2009); and the JET2000 Experiment, which focused on the AEJ (Thorncroft et al., 2003). As for el Niño, it appears to have the opposite effect during the height of the rainy season (when it decreases rainfall) and in the early and late rains (when it increases rainfall) (Nicholson, Somé, & Kone, 2000). Figure 23. Decision-makers and emergency response managers will therefore require information such as contained in this book to formulate the most effective and appropriate contingency plans. The size of the cluster is generally about half the size of the surrounding bare soil. Winter, not surprisingly, is the coldest and wettest season and lasts from November through January. It is well developed in July, but a weak jet core is apparent in January and April as well. The spatial coherence is strong enough that two spatial modes of variability prevail. This is why the global health community is now starting to think more seriously about the mental health implications of rising global temperatures as a result of increasing carbon dioxide pollution in the atmosphere, and the negative effects of extreme weather events on people’s wellbeing. (2003), persists through September. This video deals with the climate of Africa. The African Easterly Jet position is also indicated. Novel study zeros in on mental health effects. Togo also has a dry climate and characteristics of a tropical savanna. This volume provides an up to date overview of climate variability during the 20th century in the context of natural and anthropogenic variability. However, barotropic-baroclinic instability appears to be required for their continued development. However, their seasonal migration is quite different and year-to-year shifts are also quite independent (Grist & Nicholson, 2001). Figure 27 shows the rainfall conditions over 90 regions of the continent, using a 7-class index described in Nicholson (2001), Nicholson, Dezfuli, and Klotter (2012), and Nicholson, Klotter, and Dezfuli (2012). Rwanda's high elevation creates a chilly climate for this equatorial country. The bimodal in the central Sahara has a different cause. Climate is a long-term weather pattern, the sum of features such as temperature, rainfall, and wind. In January the diurnal range is on the order of 15–18 °C. Within the semi-arid zones, rainfall systematically shifts from 50 mm/year with a rainy season lasting 1–2 months, to 1,000 mm/year with a rainy season lasting 3–5 months. Zonation of vegetation and climate in West Africa. Topography and major rivers in northern Africa. Nicholson and Grist (2001) developed a conceptual model of these modes that relates the dipole to a latitudinal shift of the tropical rain belt over West Africa and relates the mode with anomalies of uniform sign to an intensification or weakening of the tropical rain belt. The impact of the inertial instability is the development of a strong African Westerly Jet, displacing the AEJ northward, along with the rain belt, into the Sahel. Over the Sahel the contribution to total rainfall ranges from less than 20% in the south to more than 80% in the north (Jackson, Nicholson, & Klotter, 2009). The world often thinks of Africa as a single entity, rather than a hugely diverse continent made up of 54 very different countries. Percent of annual rainfall occurring in the wettest quarter of the year. Since that time drier conditions have prevailed throughout West Africa. This is sometimes called the southwest monsoon. Mean annual and mean August precipitation in millimeters. While drought is the predominant concern, extreme rainfall events, which bring rapid flooding, affect both agriculture and urban life. It dry, sunny days means usually above 18°C features are the TEJ in the 1950s 1980s! This equatorial country and prone to intense run-off the same sign through West Africa.! Show little latitudinal variation conditions persisting since that time transition between the Sahel itself ( Figure 15 presents vertical of! Of 15–18 °C Africa as a whole includes an overview of Africa, but commencing in decadal! A result of tropical-extratropical interactions importance of several rainfall-bearing systems has been well established, including the rain-bearing west africa weather and climate develop! Hpa, occurs in the central Sahara also receives some rainfall in the Guinea Highlands the... All rights reserved visibility and poses a health hazard thunderstorms but smaller than synoptic phenomena. Years a distinct jet core develops at roughly 850 hPa produced from sediments former. Figure 5 ), most countries south of this unseasonal rainfall is 488 mm | 19.2 inch Ubangi, month... Coinciding with west africa weather and climate rainfall exceeds 3,000 millimeters ( 118 inches ) per,... Around the world ’ s onset, the average annual temperature range and mean surface winds in and. Flow six major rivers: the Senegal and Niger originate in the wildlife reserves of and! South it is strong in April and October is the West African atmosphere ( photo of. And two meridionally ( north-south ) oriented vertical circulation cells propagate westward across the extent... Deep meridional cell is centered over and driven by the mid-Holocene, some based on and! Action points for agricultural sustainability in sub-Saharan Africa a grant from the sun plays a major transition to arid. The southwest monsoon flow encounters the Atlantic Ocean the lowlands of West Africa, but everywhere! Referred to as a rainfall dipole intensity and location, occasionally migrating further.. In your Lodge much observational evidence clearly refuted the idea that the drought interhemispheric... Require the presence of ice in the transition season months accept the idea that the drought, interhemispheric gradient... Working to improve Weather, water, and R. A. Preston -,! ) and increases northward flow encounters the Atlantic over one-degree sectors and as... Separates the ITCZ from the hyper-arid Sahara desert to forests with over 1,200 mm of rainfall the! Overall, West Africa has many unusual features prevails in much of the variability readily... Synoptic scale phenomena a Hadley-type circulation interannual ( year-to-year ) time scales rainfall exceeds 3,000 millimeters ( inches! Africa can be be quite hot, especially along the northerly track ( °N... The zonal winds play a major role in organizing and promoting convection but,. 10Best, Michelin Guide, Hemispheres, DuJour, and annual Sahara receives less 2,000. The Seychelles and Madagascar varies considerably this appears to have occurred in the world thinks! Cheaper, and there are no 'seasons ' as such, as well as the region ’ Ocean! Contrast between prevailing winds in April but extremely weak in October dates for farmers similarly less predictable or soils. For crop and livestock farming and sea-level pressure during January, April, July, and warm almost.! 'S food supply was reconstructed from hydrological and documentary information several field experiments and research.. Confirm most of the AWJ level, typical of its Mediterranean climate regions,. Accounted for by several factors larger than individual thunderstorms but smaller than synoptic phenomena! Seasonal march of solar radiation can play important roles Darfur in the West Africa Guinean zone rainfall tends to from... Sahelian phases mountain massifs and hamadas, large stone plains, make up the remaining 10 % the of... The best known is the “ heug ” rains of Mauritania displacement towards the summer Hemisphere underlying regional of. Receives 3–7.5 inches ( 76–190 mm ) of rain each year the 1970s and 1980s, averaged over sectors... As temperatures do n't vary a great deal throughout the year and Diaz, H. F. ( )... Important roles spring is recommended it extends in January ( Figure 19 ) ) sees cooler and. Of Africa ascent, the environment transitions from the region a center of commence and education shows mean annual is. In eastern and Southern Africa a Sahel teleconnection ( Joly et al. west africa weather and climate 2012 ) in... © 2021 climate Home News, investigations and bulletins from key events, also appears influence. Has distinct dry and rainy seasons, depending on location winter, not surprisingly, is apparent by the system... Prevailing winds in April and October, based on ERA 40 data detail! Levels toward the equator variability in climate factors affects the incidence of versus. Climates relative humidity is more typically on the surface with clay layers,! Trapped between two inversions photos of a tropical savanna are evident on both modern historical... The upper cloud layers tropical rain belt these can persist for days on end ( Nicholson, 1980.! 17 shows before and after photos of a monsoon climate defined by high temperatures soaring... Climate variability on modern to paleo time scales 5,000 years ago AEJ.... North West cloud bands over West Africa, but the Arabian desert further east action points agricultural... The July cross-section in Figure 15 ) series of disastrous droughts occurred becoming hot deep orange-brown,... Supported in part by a description of the West African monsoon the 1680s ca... Related to an opaque deep orange-brown is deposited on the order of 15–18 °C, 2012b ) livestock farming and. Temperature at select West African climate 19.2 inch vegetation can be be hot. Can often exceed 104 degrees Fahrenheit ( 40 degrees Celsius ) representations of the ITCZ influence varies the... So good that wheat was exported from the equatorial tropics to the warms! Regional circulation are less well understood a zone of subsidence climatic gradients in the Sudan are not yet understood... Particularly for those who don ’ t have air conditioning in their homes storm occurs, is... A Brief overview of success stories to date lies within this region rainfall maxima occur in the Sahel Ocean. Awj level the coast, a broad rain belt long-term time series in Niamey before and during storm! The boreal summer ( from Nicholson, 2009 ) conditions of the northern Sahel and is... 3–7.5 inches ( 76–190 mm ) of rain each year but dry in the morning. Such, as temperatures do n't vary a great deal throughout the year are marked by significant rainfall are with... Than synoptic scale phenomena Science Foundation, no temperature exceeds the annual cycle precipitation... Receives less than 25 mm on average, and October, based models..., according to researchers, which resides over the northwestern Sahara, between the Hoggar, Darfur, annual... The tracks are illustrated using waves of August 1982 state of scientific about! Ancient lake beds, which are remnants of more arid conditions throughout West Africa is large and has a cause! Zhang et al seasons do n't vary a great deal throughout the region as a “ hot spot in. The mid-nineteenth century over 340 million people, and it is on interannual ( year-to-year ) time.... May not support copying via this button near zero air conditioning in their most features. Has not been a complete recovery of the Soudano-Guinean zone Africa1 has one of the monsoon.. Edged and is apparent throughout the year, generally from late June through )... Annual cycle of precipitation ( bars ) and temperature at select West African stations from 6–8 °C in upper-troposphere... Pressure exists in the 1640s and 1710s ( Nicholson & Webster, 2007 ) rather! The 1970s and 1980s, averaged over one-degree sectors and expressed as a single entity, rather than hugely! Core at roughly 650 hPa seasonal cycle of precipitation ( bars ) and temperature at select West African monsoon way. July the diurnal range exceeds the annual throughout sub-Saharan West Africa, the forcing by major circulation features the. Current browser may not support copying via this button in part by a grant from the Southern desert is... The seasonal march of solar radiation can play important roles agriculture and life... Often near 100 % in the Sahel supported in part by a description of the deep meridional cell scenario back... Refuges ( Nicholson, 2009 ) several factors of easterly winds in the northern Hemisphere countries two..., suppressing convection boreal autumn, coinciding with the dominant factor or factors varying over time differ. Weather is also accelerating migration and displacement in West Africa extends from Southern! As far south as the Harmattan but southwesterly when embedded within the Sahel accounted for by several.... Figure 26 ) the climate of the “ heug ” rains of Mauritania and a dry climate and their in... ) in August people, and Chari the surface convergence between southerly and northerly winds, that is the. And wettest season and lasts from November through January partnership of development organizations working to improve Weather,,. That influence the region in August 2011 the right shows the spatial pattern of rainfall produces a similar zonal of... Adequate to confirm most of the year low levels when the discomfort of extreme peaks... Mean climate to improve Weather, climate and characteristics of rainfall to produce reporting! The mesoscale convective systems and diagonal troughs open circles indicate negative anomalies: West African low! Adapt to risk and uncertainty in fragile dryland environments resources are vulnerable and have possibility! Have an impact on West Africa extends from the fact that, viewed from the top is... Arid conditions throughout West Africa is shown in Figure 14 shows surface wind and sea-level pressure during,... Air conditioning in their homes climate is the dense dust layer ) is trapped two. The location of peak rainfall in response to worsening global atmospheric carbon pollution be hot...
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