The majority of Africa’s population is dependent on rain-fed, subsistence agriculture. In its latest report, the IPCC [1] in 2013 evaluates the average trend of world temperature over the period 1880–2012 equal to 0.85°C with a degree of uncertainty ranging between 0.65°C and 1.06°C. It is a period of severe drought which marks a large part of the Moroccan territory. The analysis is based on the yearly series of the annual rainfall images, expressed in mm/month, drawn from the NOAA data base. (ii)In Algeria, the Constantine, Annaba, and Skikda stations located in the east of the country record a rising trend of 10% for the first station and stabilisation of values for the last two. Nouaceur, Zeineddine; Murarescu, Ovidiu. To get an overview of global rainfall variability, a pixel-by-pixel classification has been performed. Under these conditions, the depressions are pushed towards northern latitudes, which promotes the establishment of a dry and mild weather on the periphery of the Mediterranean basin and North African regions. (v)The stage covering the 1998–2001 period is marked by the return of drastic conditions. (i)The analysis of the decade 1982–1991 (map shown in Figure 3(a)) shows the predominance of drought conditions in nineteen stations which record more than 50% dry and very dry years and only 7 which correspond to wet and wetter conditions for a little over a half of the duration of the period studied. The Bertin matrix was introduced to harmonize and consolidate information after the statistical treatment. To determine the typical breaks and periods, a second procedure is conducted. Water 2020, 12, 1754. As the area experiences a bimodal rainfall regime, the CAD for each data set is further grouped into the major season, between March and July, and minor season, between Septembe… This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The World Meteorological Organisation [3] considers the period 2011–2015 as the hottest on record, and the year 2015 as the hottest since modern observations began in the late 1800s. The rainy season begins in the fall and continues to the spring. The method used to determine the modes of this variability and the trends of rainfall is the chronological graphic method of information processing (MGCTI) of the “Bertin Matrix” and continuous wavelets transform (CWT). In this paper, we test this method on a larger area consisting of different climatic regions of North Africa (more than 30 stations). This study also allowed us to highlight the durable and drastic nature of the climatic drought affecting Morocco for more than two decades (1980–2001). Copyright © 2016 Zeineddine Nouaceur and Ovidiu Murărescu. The MGCTI and its graphic representation allow a chronological reading and a spatial analysis of the phenomenon. While El Niño Southern Oscillation (ENSO) affects climate variability in the world, the North Atlantic Oscillation (NAO) is the climate model dominant in the North Atlantic region. This new period marks a break from past droughty periods despite the return, once in a while, of deficient years (e.g., in 2005 and 2006 for Algeria and Tunisia and 2006, 2007, and 2011 for Morocco). The projection of the result on a graph allows for the visualisation of the evolution of the phenomenon on a regional scale in a first stage and, in a second stage, for the determination of data on breaks and trend change. Spatio-Temporal Rainfall Variability and Rainstorm Analysis over the Goa State, India . The higher variability observed in the Indus basin varies from 12 to 87.1%, with a mean value … Author to whom correspondence should be addressed. During summer, rainfall is scarce. As explained in section 3.2, the variability of rainfall in arid and semi-arid areas is considerable. [30] find no statistical significancy in the cumulative and extreme rainfall trends (summer and winter events) in 9 stations of this last country. IPCC (Intergovernmental Panel on Climate Change) GIEC, Changements climatiques en 2013, Les éléments scientifiques, résumé à l'intention des décideurs, service d'appui technique du groupe de travail I GTI, 2013. However, the results show a contrary trend to climate models predictions [27, 28]. Our analysis has several caveats. [20], based on the results of first scenario, showed a marked decrease in winter precipitation value by the end of the 21st century. Thirty-five stations (14 in Morocco, 12 in Algeria, and 9 in Tunisia) which provide a common period of measurements were chosen for this study (1970–2013 for Algeria and Tunisia and 1970–2011 for Morocco) (Figure 1). Nouaceur, Z.; Murarescu, O. Rainfall Variability and Trend Analysis of Rainfall in West Africa (Senegal, Mauritania, Burkina Faso). [19] lead to the same result with a 20% rainfall decline south of the Mediterranean Sea according to a climate warming scenario of +2°C. The First Stage. studied the variability and time series trend analysis of rainfall and temperature in Woleka sub-basin, north-central Ethiopia. This map confirms a return of more favorable conditions throughout the entire territory, as the decrease of dry and very dry years is common at 29% of the stations (of which 14% show stabilisation of this category of humidity for the two decades). It consists in assigning a number ranging from 1 (very dry year) to 5 (very wet year) according to the already determined features assigned to each year. previous studies on rainfall variability in Northern Nigeria such as [12][11] [13] and [14] relied mainly on statistical analysis of rainfall variation in their asess- s ment of rainfall trend and drought. The last period of this precipitation series (2003–2013), in which 82% of the years have a positive regional index, is described as rainy. The regional index is positive for a period of 8 years. 9, pp. Faced with such great changes that today affect the Maghreb region and given the complexity of spatial and temporal dimensions of the climatic signal, a more thorough research of causes and retroactions would allow for a better understanding of the mechanisms behind this new trend. The spatial variability of rainfall was estimated using a coefficient of variation (CV) over the IGB . All stations under study are characterised by an almost even distribution of extreme classes of annual rainfall, rainy and very rainy (40%), dry and very dry (39.50%), and normal (20.5%). This method was used for the first time in 2013 [24]. Rainfall in Nigeria is subjected to wide variability both in time and space. Indeed, precipitation deficits in these countries are intense and may persist for long periods of time (1980–1987, 1991–1994, and 1998–2001). No genuine climatic trend stands out in this period. helio-international.org. A number of techniques have been developed for the variability and trend analysis of the rainfall time series. Recent analysis of the rainfall base for the eastern transect (Malou R. 2002; Malou R. [...] 2004) has allowed establishment [...] of future bases for rainfall variability in the east of the [...] country (Kolda and Bakel weather [...] stations) where models predict greatest change. Three data sets, described as Climate Assessment Decade (CAD), of 10 years, ranging from 1985 to 1994, 1995 to 2004, and 2005 to 2014, were categorised to allow comparison of variation in rainfall distribution in the area. The Second Stage. The percentage of rainy and very rainy years recorded at all stations (55.72%) is in net increase, while dry and very dry years, with 20.61%, are in net decrease as compared to the previous period. The mesoscale variability of the Sahelian rainfall is analysed from a series of 30 high time resolution rainfall series covering 13 years and a 110 × 160 km2 area in the region of Niamey. The purpose of this article is to show the trend of rainfall over nearly half a century and to detect the date of changes of cycles. At the same time, Algeria and Tunisia, which are part of the MENA region countries, have reached a state of absolute water scarcity. 15-16, pp. Rainfall data from 77 stations were analysed to determine the mean annual and interdecadal rainfall variability and distribution in Ghana for the period 1981-2010. Variability of rainfall can be used to characterize the climate of a region. It reveals the importance of positive differences which indicate an increase of the former category in 83% of the stations. The main objective of this paper is to assess the rainfall variability and to identify the relationship between paddy production and rainfall, by means of statistical analysis. The MGCTI is an analytical method based on a statistical analysis and on a graphical representation of results. This trend was confirmed for 2012/2013 because, with an average pluviometry of 450 mm, the excess rainfall on a national scale amounts to +20% as compared to a normal year [42]. helio-international.org. Ministry of Energy, Mines, Water and Environment, Ministère de l'Energie, des Mines, de l'Eau et de l'Approvisionnement, 2008-2009, 2009-2010, 2010-2011, 2011-2012, 201-2013. (iii)The regional index reaches, during this final year, one of the lowest values of the series, −1.41. This decade contains 70% of the years with positive regional index. Rainfall Variability and Trend Analysis of Annual Rainfall in North Africa, UMR CNRS 6228 IDEES, University of Rouen, Rouen, France, Department of Geography, “Valahia” University, Târgovişte, Romania. M. Giannakopoulos, M. Bindi, M. Moriondo, and T. Tin, “Climate change impacts in the Mediterranean resulting from a 2°C global temperature rise,” A Report for WWF, G. Tselioudis, C. Zerefos, P. Zanis, P. Repapis, and I. Kapespmenakis, “Future trends in Mediterranean precipitation and possible connections with the phase pf the North Atlantic Oscillation,” in, M. Dubrovský, M. Hayes, P. Duce, M. Trnka, M. Svoboda, and P. Zara, “Multi-GCM projections of future drought and climate variability indicators for the Mediterranean region,”, P. Alpert, T. Ben-Gai, A. Baharad et al., “The paradoxical increase of Mediterranean extreme daily rainfall in spite of decrease in total values,”. This investigation is based on the calculation of the reduced centered index and the chronological graphical method of processing information (MGCTI) of “Bertin matrix” type. Rainfall variability is expressed by the coefficient of variation (CV). In 1980, a new drier climatic phase began and lasted until 2001. In the Middle Moroccan Atlas, a situation may be noted which differs from that described for the central Moroccan region [29]. The absence of a significant trend is however dealt with in other studies [33] over a long chronological sequence of Tunis, Manouba station. Hydrological investigation over a large area requires assimilation of information from many sites each with a unique geographic location (Shahid et al., 2000, Shahid and Nath, 2002). The regional index shows that almost 63% of years record a negative value. You seem to have javascript disabled. The minimum, maximum and mean temperatures have increased significantly for most of the stations. Multiple requests from the same IP address are counted as one view. Check the following websites: WMO, World Meteorological Organisation: http://www.wmo.int/pages/index_en.html ONM, Office National de la Météorologie (Algeria): http://www.meteo.dz/ Direction de la Météorologie Nationale (Morocco): http://www.marocmeteo.ma/ IMN, Institut de la Météorologie Nationale (Tunisia): http://www.meteo.tn/default.html NCDC, National Climatic Data Center: http://www.ncdc.noaa.gov/. An analysis of only 5 or 6 years of observations is inadequate as these 5 or 6 values may belong to a particularly dry or wet period and hence may not be representative for the long term rainfall pattern. Africa ) Hydrological Sciences Journal: Vol years recorded in Tunisia, recent studies 31. Sequence of three rainy years only account for 22.90 % leaves free the passage to the ocean affecting! Faso )., 28 ] simple and effective way to establish a multivariate typology based on graphical! This phase at almost 48 %, while, during this final year, one of the lowest of. 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