DOCSLIB.ORG

The Harmattan Is a Weather Condition in the Tropics in Which Dust Particles

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Harmattan Is a Weather Condition in the Tropics in Which Dust Particles Journal of Applied Sciences Research, 2(11): 1014-1018, 2006 © 2006, INSInet Publication Perspectives on the Effects of Harmattan on Radio Frequency Waves D.D. Dajab Department of Electrical Engineering, Ahmadu Bello University, Zaria, Nigeria. Abstract: Harmattan dust clusters at its highest intensities can reduce visibility to less than a hundred meters.Similar precipitations like rain absorb and scatter electromagnetic energy leading to attenuation in its signal strength.In this paper spatial harmattan particle densities as approximated from visibility data are utilized to determine the specific particle attenuation possible on radio frequency signals.The attenuation variations obtained indicates a significant leap in the values during harmattan and non-harmattan periods.The predominant propagation mechanisms likely during the harmattan and how the loss in power is incurred in radio frequency signals are also discussed. Key words: INTRODUCTION MATERIALS AND METHODS The harmattan is a weather condition in the tropics in The records of daily meteorological observations, which dust particles (precipitates) are blown up into the obtained from the Meteorological Department of the air by winds defined as air in horizontal motion relative to Federal Airports Authority of Nigeria (FAAN9), the earth surface1 and pushed southwards from the Sahara Zaria Aerodrome,and the meteorological section of the desert by the northeast winds. Harmattan intensity may be soil science department of the Institute for Agriculcural so great that visibility at ground level is reduced to less Research(IAR10) serve as the inputs to the foregoing than a hundred meters by the dust clusters. Harmattan analyses.The data cover the periods 2001 to 2002. occurs in Nigeria during the dry season, that is, between There are three ways of evaluating the performance the months of November and March and with its of radio communication systems: by mathematical micronsize particles, harmattan dust clusters resemble that analysis, by computer simulation and by measurement. of fog and the space they cover can be considered as a The characteristics of these techniques can be summarized dielectric – since the clusters consists predominantly of as follows: quartz layer which non-coherently scatters RF signals 2. Propagation studies are required to identify the likely Mathematical Analysis: This offers quick results with a channel characteristics that would be encountered in any very good insight into what is actually happening with the operating environment in order to form the channel model process being evaluated, for example, it enables us to see of the physical layer of the communication system. the relationship between the various parameters in the Established wireless systems in the frequency range system and the effect of the variation of one parameter. between 500 MHz and 5 GHz have resulted in the However, in most cases it is necessary to make many development of different approaches to the prediction of simplifying assumptions to enable such an analysis be wave propagation. Within this frequency range are used. This is inevitably the case when communication is different telecommunication applications and services3. taking place over propagation channels with multipath Studies have shown 4,5,6 that precipitations such as those and fading. of rain, harmattan dust etc absorb and scatter electromagnetic energy which leads to attenuation in its Computer Simulation: An increasing trend in the field signal strength. Improved models are desired that explore of computer simulation of complex systems of all types the realm of overall macroscopic signal propagation in a (that is, link or physical level and network models) is local environment and that adequately captures the time- away from dedicated programs written in conventional varying behaviour of representative communication high level languages (for example, FORTRAN, C, C++) channels7. Wireless communication links are generally towards the use of high-level simulation packages, described as time-varying frequency-selective fading wherein simulation models are built up from blocks that multipath channels. The topology, link performance and are usually graphically represented and joined together in quality of service (QoS) delivered to the user is a drawing package-like environment. High level packages 8 characterized as highly time varying . of this nature are available for a wide range of application Corresponding Author: D.D. Dajab, Department of Electrical Engineering, Ahmadu Bello University, Zaria E.mail: [email protected] 1014 J. Appl. Sci. Res., 2(11): 1014-1018, 2006 areas. The area of suitable application of a package Available meteorological data on harmattan dust, depends on features such as data supported in the however, are currently presented in terms of visibility in libraries. units of distance and the question is how to relate these records of ground level visibility to the actual particle rate Measurement: This is more time-consuming than (or density) of harmattan dust in the air. It is known1 that computer simulation if hardware design or redesign is a pressure increase and a temperature decrease are required and likely to prove very expensive. However, it responsible for the movement of winds, which serve as a does provide real-time operation and the most accurate means of transporting heat, dust particles, moisture etc. estimate of performance if used in conjunction with a Here a spatial particle density ρ [g/m3] may be a channel simulator or by trialing in the real-world 11 meaningful concept, given that the dust particle carrying environment .Of these mathematical analyses method capacity of the winds depend on the relative humidity. will be applied in this paper. The spatial harmattan particle density may be Generally the problem of estimating the attenuation approximated15 by the empirical relation. of RF waves caused by the various forms of precipitation (rain, snow, fog and harmattan dust etc) is quite difficult. In practice it has been convenient to express the (VV−ρ) ρ= fm i p g/m3 (4) attenuation due to rain as a function of the precipitation i h rate 12,5,13. In the case of harmattan, no known attempt at quantifying or measuring its precipitation rate is available except the measure of how it distracts visibility (with Where Vfm - the best visibility figure for the year respect to distance). To fully understand the mechanism (period) [m] of harmattan attenuation therefore it is essential to Vi - observed (measured) visibility profile [m] 3 estimate the rate of the harmattan precipitations. ρP - mean particle density [g/m ] By analogy to the attenuation of microwaves by h - humidity profile (in decimals) [g/m3] rainfall13, the specific attenuation due to harmattan dust particles may be predicted using eqt(1) though further We will assume a state in which the harmattan experiments are required to establish the validity of this dust particles consists of a subset of the complete set interpretation. of fixed sizes (which have small details compared to the wavelength) and with a certain distribution per b arain = aρ dB/km (1) cubic meters (which may be ascertained experimentally) and then we may obtain using the adapted eqn (1) Where ρ- the rainfall rate [mm / hr] b aparticle = aρ , the specific particle attenuation variation a, b – regression coefficients which are a function of (dB/m). the frequency f, of the temperature T, of the drop size distribution and to a lesser extent, of the RESULTS AND DISCUSSIONS wave polarization The problem of calculating the values of a and b for The transmission condition is the degree of mutual a given meteorological data is given by the relations14. visibility between the transmitter and receiver antennas; the conditions that may be encountered in practice are ⎛⎞⎛⎞⎛⎞nnn line-of-sight (LOS), partial LOS and non-LOS 16. nxyx⎜⎟⎜⎟⎜⎟∑∑∑ii− ii y i b = ⎝⎠⎝⎠⎝⎠i1=== i1 i1 The periods selected for the purpose of this study nn2 capture the markedly differentiated seasons of the year ⎛⎞⎛⎞2 (2) nx⎜⎟⎜⎟∑∑ii− x (i.e. May-June and Nov-Dec). From the temperature ⎝⎠⎝⎠i1== i1 curves shown in Fig. 1, it can be observed that the onset of the harmattan corresponds to the November-December nn period during which temperatures are lowest, while May- ∑∑ybxii− June is a period corresponding to the onset of the rainy a = i1== i1 (3) (wet) season when the temperatures are moderately n higher. where – is the number of pairs of observation The low humidity which occurs at the onset of x- is the temperature observations harmattan from November makes the air to be very dry y- particle size distributions (consequently all surrounding ground materials) and the 1015 J. Appl. Sci. Res., 2(11): 1014-1018, 2006 25 May 0.035 (a) 20 0.03 icro dB) m 0.025 15 0.02 perature m 10 2002 0.015 e T 2003 ttenuation ( A 0.01 5 0.005 0 Specific 0 1 2 3 4 5 6 7 8 9 10 11 12 0 5 10 15 20 25 Month Hour of the day Fig. 1: Annual temperature profile December 800 ) (b) B 700 100 d 90 m 600 ( n 80 500 atio u 400 70 n 300 60 200 ic Atte 50 May f June 100 40 Nov peci S 0 30 Dec 0 5 10 15 20 25 -100 20 Hour of the Day Fig. 3: Specific attenuation(a) May (b) December. 10 0 5 0 5 10 15 20 25 themselves but to scattering which depends on relative Hours values of the wavelength and the size of the particles. Fig. 2: Daily average ambient relative humidity Thus, the total pathloss will be expressed as low temperatures too cause the North East winds to ⎛⎞d blow across the surface of the earth raising with it Lppo10particle() d=+ L ( d ) 10n log⎜⎟ +α d []dB an increasing content of dust particles into the air. ⎝⎠do (5) Generally, it can be observed that the appearance of harmattan is always associated with a drop in the Where d0 = 0.99 distance of the reference far field ambient relative humidity, while its absence is reflected from the transmitter by an increase.
Load more

Recommended publications
  • Winds:Towards Better Weather Forecasts in Africa
    WINDS:TOWARDS BETTER WEATHER FORECASTS IN AFRICA. KINYODA G. G Kenya Meteorological Department P.o box 30259, Nairobi. KENYA Tel: 56 78 80/Fax: 56 78 88 ABSTRACT: Poor operational meteorological network in Africa has for a long time continued to make weather forecasting difficult. Data extracted from the operational meteorological satellites is therefore vital information for this region. This paper describes, compares and evaluates the operational use of wind information disseminated via the MDD system to Africa; focussing at the Regional Specialized Meteorological Centre (RSMC), Nairobi, the African Centre of Meteorological Applications for Development (ACMAD), Niamey (Niger) and the Drought Monitoring Centre (DMC) in Nairobi. 1. INTRODUCTION 4. SCOPE In describing and evaluating the use of the wind Meteorological services rely heavily on timely information received via the MDD system, this paper :- dissemination of meteorological observations and derived • Discusses briefly the main weather/climate infuencing products.In many parts of the world telecommunications factors in Africa. This is considered important in the links provided by the WMO Global Telecommunications understanding of how the wind information is analysed, System (GTS), which is also used for interchange of interpreted and incorporated into the weather forecasts. meteorological data are satisfactory. However, extensive • Verifies qualitatively, the analysed wind information areas still suffer from a high degree of unreliability. Africa against the validating "truth" provided by a is particularly affected by the unreliability of the GTS. coresponding Meteosat imagery, over a short period. Fortunately, this region lies within the field of view of the • Finally, the MDD’s mission performance is evaluated Meteosat satellite.
    [Show full text]
  • Harmattan Haze and Environmental Health
    African Journal of Environmental Science and Technology Vol. 1 (4), November 2007 Available online at http://www.academicjournals.org/AJEST ISSN 1996-0786 © 2007 Academic Journals Editorial Harmattan Haze and Environmental Health It is the season to cover up. Beginning in November of every year and ending around March, fine particulate matter (typically 0.5 – 10 micrometers) emanating from the Sahara desert blow south, obscuring vision and laboring breathing for everyone (Figure 1). In addition, the dry dusty winds cause a variety of domestic inconveniences because of the lay- ers of dust that envelope everything both outdoors and indoors. This is harmattan season, and it is ingrained in all West Figure 1. The mosque in Abuja Nigeria, seen through the harmattan haze. Photograph by courtesy of Kipp Jones1. Figure 2. Harmattan dust storms from the Sahara desert as captured by NASA’s MODIS satellite reaches across to the Atlantic Ocean in the South, and all the way to South America and the Caribbean islands2. 1 http://en.wikipedia.org/wiki/Image:MosqueinAbuja.jpg. Figure 3. Distribution of Harm attan dust particles in W est Africa. African cultures as something to look forward to, or to dread, depending on local circumstances. Dust from the Sahara desert has global environmental effects, as documented by NASA’s satellite images showing that the dust reaches as far as South America and the Caribbean3 (Figure 2). Transcontinental and over-seas transport of Sahara dust carries fungal spores, potentially affecting agricultural productivity in distant land, enriching biological diversity. Furthermore, iron-rich Sahara dust is associated with fertilizing the oceans, leading to phytoplankton growth and carbon seq- uestration, and influencing the Earth’s radiative balance4,5,6.
    [Show full text]
  • Towards a Prediction of the Intensity of a Harmattan
    DELFT UNIVERSITYOF TECHNOLOGY FACULTY OF CIVIL ENGINEERINGAND GEOSCIENCES MARCH 29, 2019 TOWARDS A PREDICTION OF THE INTENSITY OF A HARMATTAN SEASON PRISKA VAN BINSBERGEN, 4227743 Introduction The harmattan is a seasonal phenomena in West Africa. It is a dry and warm wind which is able to transport large dust plumes. Each year during the harmattan season, between November and March, this wind reaches parts of West Africa. Harmattan winds can transport large amounts of dust originating from the Sahara and Sahel through the atmosphere. This makes dust aerosol the most common aerosol type in West-Africa [Ochei and Adenola, 2018]. These fine dust particles transported by the harmattan winds scatter light and decrease the incoming sunlight. This results in decreased visibility and dangerous situation for aviation. In addition to affecting the visibility, the har- mattan brings other negative effects as well, like health issues and crop loss. The countries in West Africa along the Gulf of Guinea (from Ivory Coast to Nigeria) suffer most from the conse- quences of the harmattan due to their location relative to the harmattan winds. Not only from a health or aviation perspective, but also from an agricultural perspective these countries are affected by the harmattan, as their crops are affected by the warm, dry and dusty harmattan winds. These are countries investing in crops like cocoa pods or cashew nuts. Those crops can be largely influenced by the harmattan winds, as they are highly sensitive to dusty and dry conditions. For these farmers, a good or bad harmattan season can make a huge difference, because crop yield can decrease significantly during a bad harmattan year [Reuters, 2016].
    [Show full text]
  • The West African Monsoon Dynamics. Part II: the ''Preonset'
    1NOVEMBER 2003 SULTAN AND JANICOT 3407 The West African Monsoon Dynamics. Part II: The ``Preonset'' and ``Onset'' of the Summer Monsoon BENJAMIN SULTAN AND SERGE JANICOT LMD/IPSL, CNRS, Ecole Polytechnique, Palaiseau, France (Manuscript received 24 October 2002, in ®nal form 21 May 2003) ABSTRACT The arrival of the summer monsoon over West Africa has been documented by using daily gridded rainfall data and NCEP±NCAR reanalyses during the period 1968±90, and OLR data over the period 1979±90. Two steps have been characterized through a composite approach: the preonset and the onset of the summer monsoon. The preonset stage corresponds to the arrival in the intertropical front (ITF) at 158N, that is, the con¯uence line between moist southwesterly monsoon winds and dry northeasterly Harmattan, bringing suf®cient moisture for isolated convective systems to develop in the Sudano±Sahelian zone while the intertropical convergence zone (ITCZ) is centered at 58N. The mean date for the preonset occurrence is 14 May and its standard deviation is 9.5 days during the period 1968±90. This leads to a ®rst clear increase of the positive rainfall slope corre- sponding to the beginning of the rainy season over this Sudano±Sahelian area. The onset stage of the summer monsoon over West Africa is linked to an abrupt latitudinal shift of the ITCZ from a quasi-stationary location at 58N in May±June to another quasi-stationary location at 108N in July±August. The mean date for the onset occurrence is 24 June and its standard deviation is 8 days during the period 1968± 90.
    [Show full text]
  • The Analysis of Influence of Weather Conditions on Atmospheric Extinction Coefficient Over Bauchi, North Eastern Nigeria
    Journal of Atmospheric Pollution, 2015, Vol. 3, No. 1, 31-38 Available online at http://pubs.sciepub.com/jap/3/1/6 © Science and Education Publishing DOI:10.12691/jap-3-1-6 The Analysis of Influence of Weather Conditions on Atmospheric Extinction Coefficient over Bauchi, North Eastern Nigeria D. Buba1, F.O. Anjorin2,*, A. Jacob3 1Department of PRE-ND, Federal Polytechnic, Bauchi State-Nigeria 2Department of Physics, University of Jos. Plateau State-Nigeria 3Department of Pure and Applied Physics, Federal University Wukari, Taraba State-Nigeria *Corresponding author: [email protected] Abstract Weather conditions are natural causes of visibility deterioration and increase in atmospheric extinction coefficient at a place. A 10- year dataset (1998-2007) of visibility and meteorological parameters such as Relative Humidity, Temperature and Atmospheric Pressure measured every 3-hour daily were analysed to examine the dependence of Atmospheric Extinction Coefficient, βext on seasonal meteorological conditions and synoptic weather patterns in Bauchi, a City in the North-eastern-Nigeria. From the visibility data obtained, the corresponding atmospheric extinction coefficient (βext) for the period under review was computed by using the Koschmieder relationship. In year 2000, when the Relative Humidity and atmospheric extinction coefficient, βext are highest, the temperature and visibility values are lowest. In 2003, when temperature (29.82°C) is highest, the Relative Humidity (42.52%) is lowest, although, the atmospheric coefficient was not at its lowest neither was the visibility (18.49km) at its highest. Of the years considered, year 2000 has the highest estimated atmospheric extinction coefficient, βext for both raining season and harmattan season.
    [Show full text]
  • Compendium on Tropical Meteorology for Aviation Purposes
    Compendium on Tropical Meteorology for Aviation Purposes 2020 edition WEATHER CLIMATE WATER CLIMATE WEATHER WMO-No. 930 Compendium on Tropical Meteorology for Aviation Purposes 2020 edition WMO-No. 930 EDITORIAL NOTE METEOTERM, the WMO terminology database, may be consulted at https://public.wmo.int/en/ meteoterm. Readers who copy hyperlinks by selecting them in the text should be aware that additional spaces may appear immediately following http://, https://, ftp://, mailto:, and after slashes (/), dashes (-), periods (.) and unbroken sequences of characters (letters and numbers). These spaces should be removed from the pasted URL. The correct URL is displayed when hovering over the link or when clicking on the link and then copying it from the browser. WMO-No. 930 © World Meteorological Organization, 2020 The right of publication in print, electronic and any other form and in any language is reserved by WMO. Short extracts from WMO publications may be reproduced without authorization, provided that the complete source is clearly indicated. Editorial correspondence and requests to publish, reproduce or translate this publication in part or in whole should be addressed to: Chair, Publications Board World Meteorological Organization (WMO) 7 bis, avenue de la Paix Tel.: +41 (0) 22 730 84 03 P.O. Box 2300 Fax: +41 (0) 22 730 81 17 CH-1211 Geneva 2, Switzerland Email: [email protected] ISBN 978-92-63-10930-9 NOTE The designations employed in WMO publications and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of WMO concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries.
    [Show full text]
  • Impact of Harmattan Sun and Dust of the Eye in a Nigeria City
    IOSR Journal of Research & Method in Education (IOSR-JRME) e-ISSN: 2320–7388,p-ISSN: 2320–737X Volume 7, Issue 3 Ver. I (May. - June. 2017), PP 36-41 www.iosrjournals.org Impact of Harmattan Sun and Dust of the Eye in a Nigeria City 1R.O.K. Meindinyo, 2M.C. Misra, $R.C. Orji 1 Department of Physics, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria, 2 University of Jos/ Jos University Teaching Hospital Jos Plateau State, Nigeria. Abstract: This work reports Studies that were carried out to investigate the impact of harmattan sun and dust on the eye. These includes ocular media absorbance, ocular related disease incidence, Sun intensity and amount of atmospheric dust during harmattan and non harmattan periods in Jos Nigeria. This is because the eye is the essential organ of sight. It functions by way of refraction of light (from objects) by the refracting media (the cornea, aqueous and vitreous humours and the lens) onto the retina. The brain which is connected to the eye through the optic nerve does the interpretation. Vision loss/blindness could result if any these parts fails to function from damage. The study showed that the harmattan season has hazardous effects on the eye. This might be because the harmattan wind from the Sahara desert is always laden with dust which coupled with increased intensity of the sun cause irritation, lacrination and burning sensational type of pains. This may later lead to other degenerative conditions of the eye especially the cornea because it highly absorbs the energy rich Ultra- violet rays which might destroy its epithelial cells.
    [Show full text]
  • Photovoltaic Power Potential in West Africa Using Long-Term Satellite Data
    Atmos. Chem. Phys., 20, 12871–12888, 2020 https://doi.org/10.5194/acp-20-12871-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Photovoltaic power potential in West Africa using long-term satellite data Ina Neher1,2, Susanne Crewell2, Stefanie Meilinger1, Uwe Pfeifroth3, and Jörg Trentmann3 1International Centre for Sustainable Development, University of Applied Science Bonn-Rhein-Sieg, Grantham-Allee 20, 53757 Sankt Augustin, Germany 2Institute of Geophysics and Meteorology, University of Cologne, Albertus-Magnus-Platz, 50923 Cologne, Germany 3Deutscher Wetterdienst, Satellite-based Climate Monitoring, Frankfurter Straße 135, 63067 Offenbach, Germany Correspondence: Ina Neher ([email protected]) Received: 30 March 2020 – Discussion started: 20 May 2020 Revised: 25 August 2020 – Accepted: 28 August 2020 – Published: 5 November 2020 Abstract. This paper addresses long-term historical changes 1 Introduction in solar irradiance in West Africa (3 to 20◦ N and 20◦ W to 16◦ E) and the implications for photovoltaic systems. Here, we use satellite irradiance (Surface Solar Radiation Data The United Nations proposed the Sustainable Development Set – Heliosat, Edition 2.1 – SARAH-2.1) and temperature Goals to achieve a better and more sustainable future (United data from a reanalysis (ERA5) to derive photovoltaic yields. Nations, 2015). The seventh goal, to “ensure access to Based on 35 years of data (1983–2017), the temporal and affordable, reliable, sustainable and modern energy for all”, regional variability as well as long-term trends in global implies a shift away from fossil-fuel-based sources towards and direct horizontal irradiance are analyzed. Furthermore, a renewable energy sources.
    [Show full text]
  • Harmattan, Saharan Heat Low and West African
    Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-309, 2017 Manuscript under review for journal Atmos. Chem. Phys. Discussion started: 15 May 2017 c Author(s) 2017. CC-BY 3.0 License. Harmattan, Saharan heat low and West African Monsoon circulation: Modulations on the Saharan dust outflow towards the north Atlantic Kerstin Schepanski1, Bernd Heinold1, and Ina Tegen1 1Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany Correspondence to: Kerstin Schepanski ([email protected]) Abstract. The outflow of dust from the North African continent towards the north Atlantic is stimulated by the atmospheric circulation over North Africa, which modulates the spatio-temporal distribution of dust source activation and consequently the entrainment of mineral dust into the boundary layer, as well as the transport of dust out of the source regions. The atmospheric circulation over the North African dust source regions, predominantly the Sahara and the Sahel, is characterised by three major 5 circulation regimes: (1) the Harmattan (trade winds), (2) the Saharan heat low (SHL), and (3) the West African Monsoon cir- culation. The strength of the individual regimes controls the Saharan dust outflow by affecting the spatio-temporal distribution of dust emission, transport pathways, and deposition fluxes. This study aims at investigating the atmospheric circulation pattern over North Africa with regard to its role favouring dust emission and dust export towards the tropical North Atlantic. The focus of the study is on summer 2013 (June to August), 10 during which also the SALTRACE (Saharan Aerosol Long-range TRansport and Aerosol-Cloud interaction Experiment) field campaign took place. It involves satellite observations by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) fly- ing on-board the geostationary Meteosat Second Generation (MSG) satellite, which are analysed and used to infer a data set of active dust sources.
    [Show full text]
  • Dust Over West Africa
    Dust over West Africa Dr. Vincent O. Ajayi Federal University of Technology, Akure, Nigeria. [email protected] Lecture outline • Introduction • Source region • Transport and trajectory • Characteristics of Bodele depression • Meteorological conditions • Mechanism of raising dust • Dust climatology • Impact of dust in West Africa • Forecasting of dust West Africa Weather zone revisited Figure 1: Weather zones relative to the surface location of ITD in August(Source: Weischet, 2000) Introduction Figure 2: Seasonal variation in latitudinal position of the ITCZ and its consequences for atmospheric conditions over northwestern Africa. Arrows indicate direction of trade winds; dust plumes are indicated by grey shadings. December, January, and February (winter) and June, July, and August (summer) are shown. (From Stuut et al., 2005.) Winter Summer Figure 3: Animation of AOT in sumer and winter, It can be noted that harmattan dust is transported to West African in Winter and towards North and South America in Summer seasons Source region Kalu (1979) identified the source region to be around Bilma Faya Largeau Western Sahara Southern Sudan Figure 4: Major dust region in West Africa as observed by Kalu (1979) Figure : The most important regions are grey shaded: PSANAF-1: Zone of chotts in Tunisia and northern Algeria; PSANAF-2: Foothills of Atlas Mountains (PSANAF-2a) and western coastal region (PSANAF-2b; western Sahara, western Mauritania); PSANAF-3: Mali-Algerian border region; PSANAF-4: Central Libya; PSANAF-5: Bodélé Depression Figure 5: Overview of potential dust source (western Chad) areas in northern hemispheric Africa (PSANAF) PSANAF-6: Southern Egypt, based on a synergy analysis by Formenti et al.
    [Show full text]
  • Climate Change Profile: West African Sahel April 2018
    Climate Change Profile West African Sahel Climate Change Profile | West African Sahel | Climate Change Profile | West African Sahel | Climate Change Profile | West African Sahel | Climate Change Profile | West African Sahel | Climate Change Profile | West African Sahel | Climate Change Profile | West African Sahel | Climate Change Profile | West African Sahel | Climate Change Profile | West African Sahel Climate Change Profile: West African Sahel April 2018 Table of contents Introduction 3 Overall ranking 3 Biophysical Vulnerability 4 Socio-economic and political vulnerability 6 Climate change, conflict and migration 9 National Strategies and Policies 11 Nationally Determined Contributions (NDC) 12 Climate Finance and key projects 14 Maps Map 1 The Sahel region 18 Map 2 Climate hotspots in the Sahel 18 Map 3 Shift of climate zones to the south 19 Map 4 Livelihood systems in the Sahel 19 Map 5 Food insecurity in the West Sahel region 20 Map 6 Gender discrimination in the West Africa Sahel 20 Map 7 Pastoral seasonal migration in the West Sahel 21 Map 8 Location of Lake Chad 21 Map 9 The shrinking of Lake Chad 22 | 2 | Climate Change Profile: West African Sahel April 2018 Introduction Mali, Mauritania, Niger, and Nigeria1. This region is one of the poorest and most environmentally degraded regions in This climate change profile is designed to help integrate the world. Drought and high inter-annual climate variability climate actions into development activities. It complements are already being felt in the region in the form of decreased the publication ‘Climate-smart = Future-Proof! – Guidelines agricultural yields, loss of pastureland, and the shrinking of for Integrating climate-smart actions into development important water bodies2.
    [Show full text]
  • Harmatten Winds, Disease and Gender Gaps in Human Capital Investment
    CDEP‐CGEG WORKING PAPER SERIES CDEP‐CGEG WP No. 54 Harmatten Winds, Disease and Gender Gaps in Human Capital Investment Belinda Archibong and Francis Annan April 2018 Harmattan Winds, Disease and Gender Gaps in Human Capital Investment ∗ Belinda Archibong † Francis Annan Barnard College Columbia University March 7, 2018 Abstract Persistent gender gaps in educational attainment have been examined in the context of differential parental costs of investment in the education of boys versus girls. This paper examines whether disease burdens, especially prevalent in the tropics, contribute significantly to widening gender gaps in educational attainments. We estimate the impact of sudden exposure to the 1986 meningitis epidemic in Niger on girls’ education relative to boys. Our results suggest that increases in meningitis cases during epidemic years significantly reduce years of education disproportionately for school-aged going girls in areas with higher meningitis exposure. There is no significant effect for boys in the same cohort and no effects of meningitis exposure for non-epidemic years. We use theory to explore different channels, highlighting income effects of epidemics on households and early marriage of girls in areas with higher exposure during epidemic years. We also use National Aeronautics and Space Administration (NASA) data to investigate the relationship between climate variables and the meningitis epidemic and explore how climate change could potentially worsen social inequality through widening the gender gap in human capital investment.
    [Show full text]