(iv)From 1995 to 1997, a short wet period marks the Moroccan pluviometry, with a spectacular increase of pluviometry (the regional index reaches +1.37 in 1996, one of the highest values of the first three decades of this series). Rep. 1108, 2013. This peculiarity makes the identification of long-term significant trends difficult [38] and shows the need to study the precipitation trend according to a global regional approach which minimises the topoclimate effect and is informed of the spatiotemporal distribution of precipitation cycles. helio-international.org. Successive stages with the same trends exceed no more than three years (1987–1989 and 2000–2003 for negative indices and 1995–1997 for positive indices). The IPCC climate models predict, for the Maghreb countries, lower rainfall and increased aridity. MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. When the signal fades or becomes negative, the pressure associated with the Azores high is lower compared to the normal value and, at the same time, the Icelandic Low is barely formed. Climatic drought recorded in Algeria and Tunisia is shorter (1987–2002) and the cycles of years of deficits not only are synchronised between the two countries but also are less extended in time and they never exceed three consecutive dry years (1987–1989, 1993-1994, and 2000–2002). The same evolution may also be encountered in the intra-Tellian plains and basins [34]. The years belonging to the dry and very dry class totalize almost 55% for all stations. The data were analyzed for the occurrences of abrupt changes in temperature and The variability of short-term global climate is generally associated with coupling phases of oceanic and atmospheric phenomena including El Niño Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). The first stage starts in 1970 and finishes in 1986 and is marked by a lack of trend. The statements, opinions and data contained in the journal, © 1996-2020 MDPI (Basel, Switzerland) unless otherwise stated. Chiara Ambrosino 1 , Richard E. Chandler 2 , and Martin C. Todd 3 View More View Less. Contribution of seasonal rainfall to the total annual rainfall in percent (CT) for each station is also computed. 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. In the first area, rains recorded very high intensities (250 mm in 3 days from the 28th to the 30th of November 2014), which represents almost 90% of the observed average annual accumulation (280 mm). Our dedicated information section provides allows you to learn more about MDPI. At the same time, one may note the low values of rainy and very rainy years that reach 50% only at Skikda, Biskra, and Tétouan and are below this level at the remaining stations. To conclude, we may say that the climate change observed during the last years is characterised by a rainfall return but with a far greater intensity. 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 hydrological situation is as satisfactory as in Morocco, judging by the Ministry of Agriculture publications: an unprecedented dam filling up which amounted to nearly 72% in 2010 and 81% in April 2013 for the 65 dams in operation and to 80.4% in March 2014, levels that had never been reached hitherto. Rainfall variability on the other hand is the degree to which rainfall amounts vary across an area or through time. This first period, just like that analyzed for Algeria, is characterised by an important variation of extreme years (two years, namely, 1981 with a negative index of −1.79% and 1982 with a positive index of +1.77, show this particularity). 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). A number of techniques have been developed for the variability and trend analysis of the rainfall time series. A little more than 60% of rainfall accumulations recorded at various stations are considered as dry or very dry. This new trend is still noticeable through a rise in intense precipitation events and a net increase of the number of floods (Sfax city very well illustrates this; the city was flooded twice in 1969 and 1982 and, despite important improvement works carried out in 1984 and the past years, it was flooded again in 2009 and 2013) [47]. Situation des ressources en eau et du remplissage des barrages durant l'année hydrologique, Direction de la Recherche et de la Planification de l'eau, 9 p (Maroc, Morocco), R. Thierry, Au fond de la khettara Lahloua, Le journal de l'IRD, IRD, Institut de recherche pour le développement, juin/juillet/août, no. The dry and very dry classes represent just over 39% of years. These rains ensured a record cereal production of 80 million quintals (for 2009/2010). [20], based on the results of first scenario, showed a marked decrease in winter precipitation value by the end of the 21st century. It represents a least in the region of high rainfall, whereas the largest in the region of scanty rainfall. The rise that occurred during the last decade (2003–2012) is +0.78°C (for a minimum of 0.72°C and a maximum of 0.85°C). Variability of rainfall can be used to characterize the climate of a region. Multiple requests from the same IP address are counted as one view. The years belonging to the dry and very dry class totalize almost 55% for all stations. Finally, Jebari et al. 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. The beginning of the period tends less to this oscillation (a sequence of three rainy years is noticeable from 1971 to 1973). The intermodel agreement for the precipitation changes is lower than for temperature [21]. 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. In Algeria, the severe disturbances (which lead to a pluviometry of over 30 mm/24 h) are on the rise in the last years (data, ONM). Giorgi and Lionello [11] estimate that significant Mediterranean rainfall decline is expected in connection with intensification of the anticyclonic circulation and a northward shift of the string of cyclonic depression areas. A & Ogunjobi K. O. 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. The persistence of drought conditions never exceeds three consecutive years. At the same time, the percentage of rainy and very rainy years at all stations reaches 52.38%. (iii)The analysis of the map shown in Figure 3(c) for the 2002–2011 period of measurements clearly illustrates the predominance of rainy and very rainy years at most stations (25). This study concerns the West African Sahel. (iii)The regional index reaches, during this final year, one of the lowest values of the series, −1.41. Asfaw et al. Indeed, the hydrological cycle acceleration under the influence of strong temperatures might lead to more rainfall and evaporation [4]. 15-16, pp. Rainfall data of some terrestrial observations networks, on the south shore of the western Mediterranean basin, confirm this change for the last decade. (ii)The second period is marked by a dry trend which lasts 16 years on this territory. In the Middle Moroccan Atlas, a situation may be noted which differs from that described for the central Moroccan region [29]. The dry and very dry classes represent just over 39% of years. Current observations in the three countries of central Maghreb (Morocco, Algeria, and Tunisia) are not consistent with these predictions. The last years of the series provide evidence of change of trend for this decade. 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. Rainfall is a dynamic phenomenon, which changes over time and space. [18] based on the future projections of regional climate model RACMO2/KNMI show that annual precipitation within the majority of Mediterranean is very likely to decrease on an average of 20%, during the period 2071–2100 compared to 1961–1990, under scenario “SRES” “A1B.” The works of Giannakopoulos et al. 1*, S.S. Mulye. The maximum and minimum monthly rainfall records did not exhibit a statistically significant trend. Only 30% of the years of this long period stretching over more than two decades show a positive regional index. 2097-2123. Review articles are excluded from this waiver policy. We can see in Figure 5(a) that, since the 2000s, the percentage developed for dry and very dry years has been clearly in constant decline in all three countries. (MK) test for trend and wavelet analyses for temporal variability were carried out for rainfall intensities at resolutions of 0.1, 0.5, 1, 3, 6, 12 h and for the monthly rainfall depths and proportion dry ratios. The first authors assign a tropical precipitation origin to the return of rains observed at the Moroccan stations of Safi and El-Jadida, while, within the whole of the central region of Morocco, drought conditions prevail. At times, this rainfall return occurs in extreme episodes as was the case of the recent floods (November 2014) which hit central and south-western Morocco (Agadir, Guelmin, and Marrakech areas). 2020. (ii)From 1991 to 1994, rainfall accumulations become negative again. Rainy and very rainy years are evaluated for this phase at almost 48%, while dry and very dry years totalize 31.31%. West Africa; climate change; rainfall variability, Help us to further improve by taking part in this short 5 minute survey, Improving Inter-Laboratory Reproducibility in Measurement of Biochemical Methane Potential (BMP), Riparian Ground Beetles (Coleoptera) on the Banks of Running and Standing Waters, Indirect Impact Assessment of Pluvial Flooding in Urban Areas Using a Graph-Based Approach: The Mexico City Case Study, Long-Term Consequences of Water Pumping on the Ecosystem Functioning of Lake Sekšu, Latvia, Water Quality of Freshwater Ecosystems in a Temperate Climate. ONM, Office National de la Météorologie (Algeria): Direction de la Météorologie Nationale (Morocco): IMN, Institut de la Météorologie Nationale (Tunisia): International Journal of Atmospheric Sciences, https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SummaryVolume_FINAL_FRENCH.pdf, http://www.ncdc.noaa.gov/sotc/global/2014/13, https://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter11.pdf, http://www.fao.org/fileadmin/user_upload/rome2007/docs/Climate_Change_Adaptation_Water_Sector_NENA.pdf. Precipitation data recorded in 1970–2013 in Tunisia (Figure 2) are characterised by a significant variability previously emphasized during the study of Morocco and Algeria series. The regional index reaches, during this final year, one of the lowest values of the series, −1.41. A comparative study with the SPI (Standard Precipitation Index) method for detecting climate drought was conducted in 2015 [41]. The MGCTI and its graphic representation allow a chronological reading and a spatial analysis of the phenomenon. 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. Alpert et al. Almost 50% of annual rainfall accumulations are considered as wet and very wet. Ruf, and M.-J. Figure 6, developed starting from the mobile average of all stations studied, sums up the main 3 stages that have affected Maghreb pluviometry during the last 44 years. On that way, areas with similar climatological characteristics can be identified. S. Nandargi. 2016, Article ID 7230450, 12 pages, 2016. https://doi.org/10.1155/2016/7230450, 1UMR CNRS 6228 IDEES, University of Rouen, Rouen, France, 2Department of Geography, “Valahia” University, Târgovişte, Romania. Starting with 2002 in Morocco and 2003 in Algeria and Tunisia, values confirm a return towards more rainy conditions, despite the persistence of extreme variability which is characterised by a brief return of dry and very dry years (2006 and 2008). WMO (Wolrd Meteorological Organization), “Statement on the status of global climate in 2012,” Tech. Research in the group aims to provide a more solid understanding of climate processes in key rainfall regions such as southern Africa, central Africa/Congo Basin, East Africa and the Sahel. Series of rainfall intensities at different This large inner sea stretching from the Strait of Gibraltar to the Lebanese coasts over an area of almost 4,000 km has a total surface of 2.51 million km. Spatio-Temporal Rainfall Variability and Rainstorm Analysis over the Goa State, India . The last map (Figure 4) displays the differences between the last two decades (1992–2001 and 2002–2011), between precipitation accumulations of rainy and very rainy years and dry and very dry years. You seem to have javascript disabled. A sequence of three rainy years (1971–1973) can be noted at the beginning of the series, while, for the rest of the period, trend inversions (dry year, rainy year) are for two successive years at most. This variability has assumed a more pronounced dimension as a result of climate change. We use cookies on our website to ensure you get the best experience. The values are relatively high for 1982 (−1.12), 1983 (−1.21), and 1986 (−0.93). This method has been successfully tested in many North African regions [28, 29, 32, 39] and in the Sahel [40]. The regional index is positive for a period of 8 years. 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. A little more than 60% of rainfall accumulations recorded at various stations are considered as dry or very dry. The method used for this study is the chronological graphic method of information processing (MGCTI) of “Bertin matrix” type. Tselioudis et al. The latter cyclic oscillation whose role is still under debate could explain the variability of rainfall in much of the Mediterranean area and support the hypothesis of a return of the rains marking the end of years of drought in central Maghreb. Variability analysis involves the use of coefficient of variation (CV), standardized anomaly index (SAI), precipitation concentration index (PCI), moving average and seasonality index (SI). This long period characterised by a lack of humidity is followed by three years (1988–1990) during which positive regional indices and a humid trend are recorded. This last trend is also confirmed by [32] for north-eastern Tunisia. When the anticyclone retreats south, it leaves free the passage to the ocean disturbances affecting North Africa. CV is defined as the ratio of standard deviation to mean in percent, where mean and standard deviation are estimat - ed from rainfall data. This study showed the simplicity and clarity of the results obtained with the MGCTI method. Dry years reach 50% only at three stations (Marrakech, Sefrou, and Sfax). Complete analysis of rainfall events requires a study of both its spatial and temporal extents. Depending on data position in relation to limit values, the years are considered as(i)very dry, below the first quintile;(ii)dry, between the first and the second quintile;(iii)normal with trends towards drought, between the second quantile and the third quintile;(iv)rainy, between the third and the fourth quintile;(v)very rainy, above the fourth quintile. The Sahelian climate is characterized by a long dry season and a rainy season which starts in June and ends in September–October. The MGCTI is an analytical method based on a statistical analysis and on a graphical representation of results. Quality and homogeneity of the data were tested by these services. [21] analyzed future climate conditions for the Mediterranean region based on 16 Global Climate Models. On the whole, this area is characterised by a well-defined summer drought and, depending on the subregions, by a maximum precipitation in autumn or winter [13]. Valony, Gouvernance d'une oasis dont l'eau provient quasi exclusivement de l'exploitation traditionnelle des galeries drainantes, les khettaras: le cas de SKOURA au Maroc, Atelier international à Tunis 4–6, Novembre 2010, A. Daoud, “Retour d'expérience sur les inondations dans l'agglomération de Sfax (Tunisie méridionale) de 1982 à 2009: de la prévention à la territorialisation du risque,”, J. I. López-Moreno, S. M. Vicente-Serrano, E. Morán-Tejeda, J. Lorenzo-Lacruz, A. Kenawy, and M. Beniston, “Effects of the North Atlantic Oscillation (NAO) on combined temperature and precipitation winter modes in the Mediterranean mountains: observed relationships and projections for the 21st century,”. 4, 2008, P. Lionello, J. Bhend, A. Buzzi et al., “Cyclones in the Mediterranean region: climatology and effects on the environment,” in, F. Jin, A. Kitoh, and P. Alpert, “Water cycle changes over the Mediterranean: a comparison study of a super-high-resolution global model with CMIP3,”, C. C. Raible, B. Ziv, H. Saaroni, and M. Wild, “Winter synoptic-scale variability over the Mediterranean Basin under future climate conditions as simulated by the ECHAM5,”, S. O. Krichak, J. S. Breitgand, R. Samuels, and P. Alpert, “A double-resolution transient RCM climate change simulation experiment for near-coastal eastern zone of the Eastern Mediterranean region,”, C. M. Philandras, P. T. Nastos, J. Kapsomenakis, K. C. Douvis, G. Tselioudis, and C. S. Zerefos, “Long term precipitation trends and variability within the Mediterranean region,”. At the same time, the temperature trend continues to be rising (despite a slight cooling of values recorded during the last years). Previous research shows that intraseasonal rainfall variability can have an even larger impact on crop yields. Indeed, from 2008 to 2010, the percentage of rainy and very rainy years goes from 78.57% to 85.71% and 92.85%. The evolution of precipitation accumulations of extreme years (1982–2011). Indian Institute of Tropical Meteorology, Pune 411008, India nshobha@tropmet.res.in . The combined effect of climate change and anthropic impact would entail a lack of water for almost 290 million people. It reveals the importance of positive differences which indicate an increase of the former category in 83% of the stations. The effects of climate changes are also manifested in this country by extreme events (a succession of hot episodes in 2015 with a threshold temperature of 50°C exceeded at Ourgla on August 2nd 2015 and of snowfall in the Assekrêm mountains in Hoggar massif located in southern Algeria, a very rare fact never observed since 1945). Mobile frequency averages of stations that recorded dry and very dry years (a), rainy and very rainy years (b), and normal years (c) (1970–2011 for Morocco and 1970–2013 for Algeria and Tunisia). It is a period of severe drought which marks a large part of the Moroccan territory. Thus, 2013 is one of the warmest years recorded in Tunisia since 1950 [23]. In 1980, a new drier climatic phase began and lasted until 2001. The MGTCI graphical matrix shows once more three major characteristic periods:(i)The first stage starts in 1970 and finishes in 1986 and is marked by a lack of trend. This return of rainfall over central Maghreb, should it be confirmed, could mean the end of several decades of recurrent droughts and announce a durable return to “the normal.” This assumption is supported by emphasizing the impact of different world climate oscillations (North Atlantic Oscillation; El Niño Southern Oscillation) for all the continents and particularly for the African continent [27, 48]. By Akinsanola A. (2018). ANOVA decomposes the variation into “systematic” and “random” components. The National Climatic Data Center, NCDC, considers the year 2014 as the warmest ever recorded, with an anomaly of +0.69°C (calculated for the period 1880–2014) [2]. These investigations should integrate and quantify the role of terrigenous aerosols in the dynamics of local climate and show the importance of sea surface temperatures in regulating rainfall. 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. Analysis of Rainfall and Temperature Variability Over Nigeria . studied the variability and time series trend analysis of rainfall and temperature in Woleka sub-basin, north-central Ethiopia. The signs of change are extremely eloquent for the latest years in all this region of North Africa, as evidenced by the rainfall observed between September 2008 and September 2009 In Morocco [42]. The last period of this precipitation series (2003–2013), in which 82% of the years have a positive regional index, is described as rainy. Spatial distribution of precipitation stations used for this study. This decade contains 70% of the years with positive regional index. 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. On the Atlantic coast, Casablanca and Safi are the other two stations in this vast country that manifest a stable trend of extreme years regarding this last category. If, on a global scale, the increase in temperatures is unquestionable, the evolution of world pluviometry is much more contrasting as it is subject to a strong spatiotemporal variability. Analysis of monthly rainfall data from GMet between 1985 and 2014 established a pattern of variability. 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. Rainfall in Nigeria is subjected to wide variability both in time and space. Results show a rain resumption observed in the recent years over the Sahelian region and a convincing link with the surface temperature of the Atlantic Ocean. [22] confirm a tendency of intense rainfall increase in Spain and Italy and also note an absence of trend in Israel and Cyprus. The percentage of average year reaches 25.71%, while, during dry years, it represents 27.14%. As for rainy years, they exceed 40% at all stations, except Dar el Beïda, Djelfa, and Gafsa. "Rainfall Variability and Trend Analysis of Rainfall in West Africa (Senegal, Mauritania, Burkina Faso)." This graphical representation allows us to see the evolution of extreme rainfall for the two already discussed periods. The 2009-2010 rainfalls are also considered as exceptional and historic because they allowed for the filling of dams at their maximum capacity (the filling rate of the Al Wahda Dam, the largest of the kingdom, located in the Ouergha Wadi, was 98.5%). Rainfall in Nigeria is subjected to wide variability both in time and space. 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. A decrease is recorded only at three stations (Dar el Beïda, Djelfa, and Gafsa), while, for Constantine, Marrakech, and Sfax, stabilisation of values of 0% can be noted. 16, 2007, M. El Faiz and T. Ruf, “An introduction to the khettara in morocco: two contrasting cases,” in, Institut de Recherche pour le Développement (IRD), “Les réseaux d’eau anciens ressuscitent en Méditerranée,”, M. Mahdane, S. Lanau, Th. The results of statistical and graphical processing of central Maghreb pluviometry show strong variability (typical of the Mediterranean climatic domain) and an organisation structured into three main climatic periods (Figure 2). 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%). the rainfall variability in the recent past. 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. The first humid stage is noticeable from 1970 to 1979, followed by the great climatic drought which lasts almost a half a century and, finally, the rainfall return which can be noted as of 2003. helio-international.org. The First Stage. 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. 6: 1754. When estimating the impact of rainfall variability, we focus on one specific type of variability: variation from year to year. 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. Their results showed intra and inter-annual variability of rainfall and the annual, small, and main rainy seasons indicated a declining trend at a rate of 15.03, 1.93, and 13.12 mm per decade, respectively. This study was conducted on 27 Sahelian climatic stations in three countries (Burkina Faso, Mauritania, and Senegal). Content uploaded by Ataur Goni Polash. Abstract-This study investigates rainfall and temperature variabilities in Nigeria using observations of air temperature (C) and rainfall (mm) from 25 synoptic stations from 1971o -2000 (30years). To complete the preliminary analysis, an analysis of variance (ANOVA) was used to indicate the predictability of the daily rainfall sequence. To demonstrate this new trend, a detailed regional analysis of rainfall evolution is conducted. As explained in section 3.2, the variability of rainfall in arid and semi-arid areas is considerable. The spatial variability of rainfall was estimated using a coefficient of variation (CV) over the IGB . Among the retained indices, relative humidity and El Niño accounted for the highest degree of explained variability. These numbers thus indicate an increase of years in the first class of +25% as compared to the previous period and a regress of the arid and very arid class of −23.64%. Sign up here as a reviewer to help fast-track new submissions. Decades ( rainy and very wet classes show that almost 42 % of years record a negative.... Annual of rainfall of a region is conducted Sahelian climatic stations in three countries of central (... 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Is achieved vary across an area or through time years ).,! Figure 2 ) shows, for the variability and change in the Middle Moroccan Atlas, a pixel-by-pixel classification been... Announce a new drier climatic phase began and lasted until 2001 Tropical,! This territory other hand is the degree to which rainfall amounts vary across area... Intra-Tellian plains and basins [ 34 ], opinions and data contained in the Republic Benin. An even larger impact on crop yields 24–26 ] to learn more about MDPI the results obtained with IPCC! Of this water mass on a regional scale explains the vast expanse in space of the variability! Totalize almost 55 % for all parts of the data that rainfall variability analysis according! S population is dependent on rain-fed, subsistence agriculture into “ systematic ” and “ ”! 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African Monsoon ). help fast-track new submissions authors declare that they have no competing interests, we on... Morocco, Algeria, an organisation of rainfall can be identified second period is generalised in the region of.. Anticyclone moves North allow a chronological reading and a spatial analysis of the user the Moroccan..