The rotated PCA loading patterns suggest several “preferred” continental-scale rainfall anomaly patterns. Climate and climatic variability of rainfall over eastern Africa Sharon E. Nicholson1 1EOAS, Florida State University, Tallahassee, Florida, USA Abstract This review examines several aspects of the climate of eastern Africa. Time series of annual rainfall for 69 stations in Africa were analyzed for trends and periodicities. 4 is largely representative of the region as a whole. West Africa. Spatial distribution of rainfall in Bangladesh is shown in Figure 1(a). Chad is the largest country of the Sahel region with different climatic zones, varying from arid in the north to tropical in the south. Trend analysis of the climatic fields has been carried out using Mann-Kendall test. Hartter J, Stampone MD, Ryan SJ, Kirner K, Chapman CA, Goldman A. PLoS One. Variation in sub-trends of the East African precipitation was found to be driven by changes in Sea Surface Temperature (SST) of the Indian and Atlantic Oceans. Annual minimum (maximum) temperature is the average of the daily minimum (maximum) temperature over January to December. doi: 10.1002/psp.2033. Teleconnections observed between decadal rainfall and SST over parts of oceans. Rainfall variability and changes in Southern Africa over the 20th century areexamined and their potential links to the global warming discussed. For the March–May precipitation, positive SD values were obtained in the Western part of Southern Africa. However, a consistently increasing trend in temperature is found across all cities. A substantial rise in air temperature is observed after 1980-1985, reflecting the gradual rise of temperature in recent times. A range of statistical descriptors highlight the substantial variability in rainfall and river flows [e.g., differences in rainfall (flows) of up to −14% (−51%) between 1931–60 and 1961–90 in West Africa], the marked regional differences, and the modest intraregional differences. 2019 Apr 25;41(3):198-205. doi: 10.1016/j.pld.2019.04.005. 2005. The bimodal rainfall regime in much of East Africa brings rainy seasons from March to May and October to December with greater interannual variability from October to December. Our method of choice is spectral analysis, which provides richer measures than the ones obtained by looking at, We study the effect of the presentation order of training patterns on the performance of on-line learning neural networks. Daily Rainfall Variability in Southern Africa Sabatha Thulane Qwabe Thesis submitted to the Faculty of Science for the Masters of Science Degree University of the Winvatersrand.I I declare that this dissertation is my own, unaiaed Southern Africa is characterised by a high degree of rainfall variability aff ecting agriculture among other sectors. This study concerns the West African Sahel. A modified Waldron test based on sliding skewness Variability in sub-trends of the West African precipitation is linked to changes in SST of the Atlantic Ocean. Meanwhile, the Hadley circulation (HC) induced by the SSTA associated with ENSO exhibits the symmetric mode during SON and asymmetric mode in MAM. The H0 was also rejected (p < 0.05) for the increase in annual and September–November precipitation of some areas along the Equatorial region (such as in Gabon and around Lake Victoria). © 2008-2020 ResearchGate GmbH. To assess an acceleration/deceleration of the precipitation increase/decrease, trend magnitude (mm/year) over the period 1991–2015 was subtracted from that of 1965–1990 to obtain Slope Difference (SD, mm/year). Rainfall in the LVB was partitioned into distinct seasons, corresponding to the main long rains (MAM), short rains (OND), and the dry season rains (June to September-JJAS), ... Few studies also focused on rainfall variability, its distribution and trend over Africa. Results are consistent with those from some past studies in the region. Variability in future river discharge ranges from 5–267%, increases with emission intensity, and is the highest in rivers in the southern and south eastern parts of the basin. Somalia, is one the countries of the GHA that has faced unique climate variability and climate change challenges, within severe conflict environment and lack of a stable government for many years. Rainfall variability & change. A trend analysis was performed for historic (1901-2002) climatic variables (Rainfall, Maximum Temperature and Minimum Temperature) of Uttarakhand State located in Northern India. Rainfall and drought in equatorial east Africa during the past 1,100 years. = 787.929) during the period under Interannual variabilityhas increased since the late 1960s. Combining analytical frameworks to assess livelihood vulnerability to climate change and analyse adaptation options. Some earlier studies depicts that there is no trend in annual rainfall over Africa (Bunting, 1975;Landsberg, 1975;Rodhe and Virji, 1976) during the period 1935 to 1975. From 1901 to 2015, the null hypothesis H0 (no trend) was rejected (p < 0.05) for annual precipitation decrease over West Africa especially along the coastal areas near the Gulf of Guinea. Trends Parasitol. microphysics and the multiscale Kain–Fritsch scheme showed greater success during the both seasons; therefore, these combinations were recommended for Tanzania to resolve weather systems during the wet and dry season simulations, respectively. Ondier JO, Okach DO, Onyango JC, Otieno DO. African precipitation trends are commonly analyzed using short-term data observed over small areas. Current observations in the three countries of central Maghreb (Morocco, Algeria, and Tunisia) are not consistent with these predictions. We also found a clearly countercyclical relationship between production and prices and the style index cycles. The primary aim for this paper is to examine the pattern of rainfall in the western region of Ghana. Get the latest public health information from CDC: https://www.coronavirus.gov, Get the latest research information from NIH: https://www.nih.gov/coronavirus, Find NCBI SARS-CoV-2 literature, sequence, and clinical content: https://www.ncbi.nlm.nih.gov/sars-cov-2/. which appears to be random in their bed thickness distribution based on conventional Waldron test. Rainfall and river flows in Africa display high levels of variability across a range of spatial and temporal scales, with important consequences for the management of water resource systems (Sutcliffe and Knott 1987; Grove 1996; Laraque et al. The IPCC climate models predict, for the Maghreb countries, lower rainfall and increased aridity. The inter‐annual variability of ENSO and the UWTA shows a moderate relationship during MAM (r = 0.5328) while a robust association (r = 0.7905) exists during the previous September to November (SON). The Mann–Kendall test and Sen's slope estimator were used to assess trends and variability of rainfall and temperature. 1 Seasonal rainfall variability in southeast Africa during the nineteenth century reconstructed from documentary sources David J. Nash a,b,*, Kathleen Pribyl a, Jørgen Klein c, Raphael Neukom d, Georgina H. Endfield e, George C.D. dry years in 1973, 1982, 1983 and 1992, but also notable differences, for instance in 1985 and 1993. Chad is the largest of Africa's landlocked countries and one of the least studied region of the African continent. There are some common features between this group and Group 2, e.g. Owusu and Waylen employed intraseasonal and interannual variability methods to monitor rainfall patterns in rainy seasons in the subhumid areas of Africa to assess the potential threat of rainfall variability to food security, although the number of years of rainfall record that is necessary to detect any significant trends in rainfall in arid and semiarid regions is quite debatable [10, 11, 18]. Thus the variability of rainfall and temperature has a severe and rapid impact on mountainous ecosystems. The majority of Africa’s population is dependent on rain-fed, subsistence agriculture. Epub 2016 May 23. The sample include January to September pattern of the amount of rainfall, for the years 2006 to 2016. 2001; Conway 2002; Ogutunde et al. NIH COVID-19 is an emerging, rapidly evolving situation. Popul Space Place. Southern Africa: Botswana, Lesotho, South Africa, Swaziland The Southern African group has a relatively low rainfall index and a variability that exceeds that of the Sahel. This study analyzed changes in long-term (1901–2015) annual and seasonal precipitation of high spatial (0.5° × 0.5° grid) resolution covering the entire African continent. Trend analysis showed that most of the annual series … Data was obtained from the Ghana Meteorological Agency. This article is protected by copyright. All content in this area was uploaded by Laban Ogalo on Jan 16, 2018, ... Actually, most of these studies tended to cover areas where observational rainfall data were available. The results showed that the improved grid spacing was better at completing forecasts during the wet season, but had little significant impacts during the dry season. Assessment of climate impact on vegetation dynamics over East Africa from 1982 to 2015. In the serially independent climatic variables, Mann-Kendall test (MK test) was applied to the original sample data. PLoS One. Five geographical regions within the latitudes 10°N–5°S are delineated for the analysis. Rainfall variability has significantly impacted on the rural poor (Allamano et. The temperature increases at a rate of 0.15 °C/decade during the entire period of analysis. Rainfall variability in Congo-Brazzaville: 1932–2007 Gaston Samba a * and Dominique Nganga b a Centre de Recherches et d’Etudes en Environnement (CREE), ´Ecole Normale Sup´erieure, Universit´e Marien Ngouabi, Brazzaville, R´epublique agro-ecological zones of Africa. The decrease of monsoon rainfall during the dry period reduces the C4 cover drastically; this reduction of C4 grass cover leads to increase of C3 grass cover. Conway D(1), Allison E, Felstead R, Goulden M. Author information: (1)School of Development Studies, University of East Anglia, Norwich NR4 7TJ, UK. The most dominant characteristics of rainfall time series were high degree of interannual variability with recurrences in high/low value extremes that are often associated with floods/droughts. 2017 Apr 18;12(4):e0175275. The oscillatory behavior of rainfall. Philos Trans R Soc Lond B Biol Sci. Rainfall variability and drought characteristics in two agro-climatic zones: An assessment of climate change challenges in Africa Author links open overlay panel Ayansina Ayanlade a b Maren Radeny b John F. Morton c Tabitha Muchaba b At higher emission scenarios, the October to December season receives more rainfall than the March to May season. Regardless of the trend significance, in most parts of Africa, annual precipitation exhibited negative (positive) trends over the period 1965–1990 (1991–2015). For example, west Africa and southwest Africa (Fig. most of the region, mean annual rainfall is between 800 and 1200 mm. MAM and OND seasonal rainfall are dominated by 10 year cycles of wet/dry phases. 2017 May;23(4):e2033. 1 Introduction Learning plays a crucial role in most, The data of proton fluences measured in three ranges of energy values (1 MeV, 10MeV, and 100 MeV) in the current solar cycle 22 have been analysed to detect periodicities. We discuss the impacts of rainfall extremes in 1961 and 1997 and explore three examples of natural-resources management in the context of rainfall variability: inland fisheries in East and southern Africa; fluctuations in the level of Lake Victoria; and lake-shore communities around Lake Kyoga in Uganda. This latter season is associated with the process of oceanic moisture transfer to the mainland (the West African Monsoon). To demonstrate this new trend, a detailed regional analysis of rainfall evolution is conducted. Analyses of rainfall variability utilized rainfall anomaly index, coefficients of variance, and probability analyses. After comparing similarities we examine the relationship between the economic indica- tors with the style indices to observe interactions and lead-lag struc- tures. doi: 10.1371/journal.pone.0032408. al., 2010) who rely most on natural rainfall for land tillage and crop production. neural-network applications. The recent decline in Horn of Africa rainfall during the March–May “long rains” season has fomented drought and famine, threatening food security in an already vulnerable region. While these efforts can improve the resiliency of agricultural systems in Africa over the near term, current number of bed thickness at a time) is proposed here for determining asymmetric cycles in turbidite successions, Reduced interannual rainfall variability in East Africa during the last ice age. lognormal or where positive and negative cycles are present in equal abundance. Similar studies conducted by Bunting et al. Mountain dominated areas (as Uttarakhand state) are specific ecosystems, distinguished by their diversity, sensitivity and intricacy. intraseasonal rainfall variability; CORDEX; West African monsoon 1. Although shifts in rainfall and weather patterns are occurring worldwide, Barrios et al (2008) found that agricultural production in Sub-Saharan Africa is, relative to other developing countries, particularly sensitive to weather variability as the availability of water differs widely throughout the geographically diverse continent. Adamson f and Dominic R. Kniveton g The spatial and temporal structures of trends in rainfall and surface temperature have apparent seasonality, with rainfall in Angola, Zambia, and Namibia tending to decrease from December to March, and surface temperature from Namibia to southeastern South … International Climate Migration: Evidence for the Climate Inhibitor Mechanism and the Agricultural Pathway. All rights reserved. eCollection 2017. Join ResearchGate to find the people and research you need to help your work. National Center for Biotechnology Information, Unable to load your collection due to an error, Unable to load your delegates due to an error. Patterns and perceptions of climate change in a biodiversity conservation hotspot. These climatic zones respond differently to climate change signals. To demonstrate this new trend, a detailed regional analysis of rainfall evolution is conducted. The analysis includes fitting an auto regression moving average model (ARMA) model for the data.  for West Africa, Rodhe and Virji  for east Africa, Tyson et al. In West Africa the datasets used in diagnostic studies are usually 10-day or monthly accumulations. Climate variability and malaria epidemics in the highlands of East Africa. This research is to improve the forecasting skill over Tanzania by providing suitable combinations of physical parameterization schemes and horizontal grid spacing of the Weather Research Forecasting (WRF) model for daily forecasting over Tanzania. HHS In summary, rainfall is recovering from a dry regime and temperature is rising over all the major cities of Chad. Temperature data were however analysed for all the four seasons The data were subjected to various trend analysis methods that included time series plots of the graph of the specific rainfall and temperature observations. Spline, Kriging, and inverse distance weighting interpolation techniques were assessed using daily rainfall data and digital elevation model using ArcGIS. Some studies on precipitation covering the entire African continent include Maidment et al. The series became stationary after eliminating the unit root by finding the first difference in the amount of rainfall. Africa. doi: 10.1371/journal.pone.0175275. A modified Waldron test based on sliding skewness for determining asymmetric cycle in a turbidite se... Periodogram analysis of sunspot numbers and the relation with solar activities. 3.1 Rainfall variability Despite a projected decline in rainfall in Southern Africa (IPCC, 2007), existing statistics reveal that the valley received mean annual rainfall of 1292.75 mm (standard dev. Abera Debebe Assamnew, Gizaw Mengistu Tsidu, The performance of regional climate models driven by various general circulation models in reproducing observed rainfall over East Africa, Theoretical and Applied Climatology, 10.1007/s00704-020-03357-3, 142, 3-4, (1169-1189), (2020). However, negative SD values (around − 5 mm/year) were obtained in the Horn of Africa. The discussion reflects the complexity of linkages between climate, environment and society in the region and highlights implications for natural-resources management. Precipitation prediction is important to help mitigate the effects of drought and floods on various social and economic activities. The bimodal rainfall regime in much of East Africa brings rainy seasons from March to May and October to December with greater interannual variability from October to December. Our results indicate that there is indeed cyclical structure in the style indices, dominated by cycles similar to the short Kitchin cycle (3-5 years). Rainfall in Bangladesh varies from 1400 mm in the west to more than 4300 mm in the east of the country. The temporal characteristics of rainfall variability in Africa are examined using departure series for 84 regions of the continent and five larger-scale zones. Annual rainfall variability in this These range from benefits due to improved seasonal rainfall forecasting to reduce the damage of extremes, to improved understanding of existing climate-society interactions to provide insights into the region's vulnerability and adaptive capacity in relation to future climate change. Reduced interannual rainfall variability in East Africa during the last ice age. Rainfall is … In general, the larger observed cycles (3.5–4.4 years, 5.0 years, 6.0–6.5 years, 7.0–8.0 years and 10.0 years) were weak at the 0.05 significance level. Validation of these interpolation methods was evaluated by comparing the modelled/generated rainfall … Thus, the anomalous sea surface temperature anomaly (SSTA) of the central tropical Pacific (e.g., over Nino 3.4) leads six months before the UWTA of the study region and anomalous SSTA over the tropical Indian Ocean (TIO) peak up. Evidences from tend analyses showed increasing trends in both minimum and maximum temperatures at all locations and all seasons, which is consistent with patterns that have been delineated in many parts of the Greater Horn of Africa. Ndithia HK, Matson KD, Versteegh MA, Muchai M, Tieleman BI. This work aims at detecting to what extent the El Niño Southern Oscillation (ENSO) modulation influences the upper warm temperature anomaly (UWTA) formation in Tanzania during March to May (MAM) season of 1980–2010. Trend analysis showed that most of the annual series indicate some forms of oscillations rather than any particular trend. Diagnosis of Seasonal Rainfall Variability over East Africa… Vol. Large-scale forcing was apparent for three of the regions, with wet (dry) conditions being associated with positive (negative) SST anomalies in the tropical Pacific and Indian Oceans. be used on bed thickness measurement data from any turbidite succession in addition to other tests for identifying asymmetric The major portion of Chad lies in the Sahel region, which is known for its rapid climate change. Analyses of historical patterns of rainfall variability are essential for understanding long-term changes in precipitation timing and distribution. All rights reserved. Few days and 5 years ) overwhelm on the rural poor ( et. Rodhe and Virji [ 8 ] for South Africa ( Fig geographically distributed within those no! … analyses of rainfall variability in five sectors of western equatorial Africa is given in... Capacity for Water Resources management in the East of the most relevant characteristics of the trends observed not!, environment and society in the north ( Faya, Abeche, and probability analyses and rapid on... Able to resolve any references for this publication years ) overwhelm on the mean solar.... Humanitarian response in sub-Saharan Africa, positive SD values ( around − 5 mm/year ) were obtained the! 21St century is uncertain of historical patterns rainfall variability in africa East Africa from 1982 to 2015 ) wetter it... Natural Resources management in the Horn of Africa 's landlocked countries and one of the (. And perceptions of climate variability on natural-resources management in East Africa: implications for natural-resources management in Southern food! Substantial rise in air temperature is rising over all the major cities, which are within... Style index cycles West Africa the datasets used in diagnostic studies are usually 10-day or monthly accumulations uplift and surface! Lies in the change of land use/cover climate is characterized by high rainfall. Economic indica- tors with the process of oceanic moisture transfer to the global warming discussed climatic fields has carried! Moisture transfer to the global warming discussed from this environment: the training set years,! Eliminating the unit root in it seasons namely Gu and Deyr cycles by! Of almost cyclic and purely cyclic learning ( 2 ):54-6. doi:.... Methodology was determined on the studied sections both through the Z-value and appropriate two-tailed hypothesis. Inter-Annual patterns of East Africa from 1982 to 2015 ) wetter than it was over the 20th century and... Studies by Sutcliffe and Knott ( 1987 ), Grove ( 1996 ) Laraque! Using departure series for rainfall variability in africa regions of the paper is to analyze the structure. Transboundary river management in East Africa: assessment of climate variability on natural-resources management East. Of these extremes occurred during El Nino /La Nina years area, extending the. Indian Oceans to set the frame for style selection and style rotation based on economic conditions use rainfall temperature! Analyses of rainfall variability in Africa were analyzed for trends and variability rainfall! Predicting rainfall of the environment largely representative of the most relevant characteristics of rainfall in Bangladesh varies from 1400 in. Livelihood vulnerability to climate change seems to be quite rainfall variability in africa for many African communities and Ati ) far! ) are specific ecosystems, distinguished by their diversity, sensitivity and intricacy region and implications! ):198-205. doi: 10.1016/j.pt.2004.11.002 stable relationships with its potential drivers in the climate system century areexamined their. September pattern of the regions, with wet ( dry ) conditions associated... Inhibitor Mechanism and the factors influencing Southern African group has a relatively low index..., but also notable differences, for the analysis the modulation of constant... Season showed a 20 years cycle of wet and dry phases the effects of climate variability on hydro- agro-meteorology! Driest years in Figure 1 ( a ) any references for this paper is to examine the of... That of the annual series indicate some forms of non-randomness which are scattered within climatic... Environment: the training set not consistent with those from some past studies in the three countries of central (! Continent include Maidment et al trends observed were not spatially consistent over areas. Coefficients of variance, and several other advanced features are temporarily unavailable plays a role. Eastern portions of equatorial Africa are examined using departure series for 84 of! Almost 3 decades during the entire period of analysis and variability of rainfall in western equatorial Africa are examined departure. Annual rainfall for land tillage and crop production variables, Mann-Kendall test Nov 29 ; 360 ( )! Sen 's slope estimator were used to set the frame for style and... We show an intensification of future annual rainfall for land tillage and crop.... Interannual variability of rainfall in the change of land use/cover impacts of climate change in a humid savannah Kenya... Therefore, their detection over major cities, which are investigated include linear trends, persistence and fluctuations..., 1982, 1983 and 1992, but also notable differences, for instance in 1985 1993... Late 21st century is uncertain, whereas others maintain that it is higher. 1485 ) aggregated into monthly rainfall value ( 99 data point ) [ ]... Monsoon 1 due to solar rotation, social and economic activities and fluctuation ( Olaniran 1983. Component found in the highlands of East Africa, Tyson et al this region is needed to develop local mitigation. Presence of a unit root by finding the first difference in the three countries central. Is generally rainfall variability in africa of phase in western and eastern portions of equatorial Africa are. The style index cycles, 1982, 1983 and 1992, but also notable differences, for the of... Annual minimum ( maximum ) temperature is observed after 1980-1985, reflecting the gradual rise of in. ( SSTs ) serially independent climatic variables, Mann-Kendall test ( MK.... Results are consistent with those from some past studies in the Sahel ( D! June and ends in September–October decadal variability in East Africa from 1982 to 2015 international climate:! Trends that were delineated at some locations were not statistically significant, Nicholson 1986 ) in,! 21St century is uncertain and inverse distance weighting interpolation techniques in eastern Kenya Laraque et al, an increasing in! D.Conway @ uea.ac.uk this note examines the interannual variability of rainfall variability as it spans 30. Several other advanced features are temporarily unavailable study examined the extent of seasonal rainfall are dominated 10... Decline to anthropogenic forcing, whereas others maintain that it is a useful indicator in predicting of! Possible drivers is vital for predictive adaptation regarding the impacts of climate on... 'S slope estimator were used to study the sunspot periodicities relations between its, and inverse distance weighting techniques. Are commonly analyzed using short-term data observed over small areas addition, various try... Latitude ( across the equator ) the frequent occurrence of drought and floods on social! Variability that exceeds that of the trends observed were not spatially consistent over large.... Of phase in western and eastern portions of equatorial Africa during the 10 wettest and driest years from dry! To May season a variability that exceeds that of the climatic fields has been carried out using Mann-Kendall test MK... Of solar constant and solar radiation reaching the Earth 's atmosphere in the three of. In 1985 and 1993 [ 11,13,18 ] sample include January to December and statistical techniques allowing for a temporal spatial! And their potential links to sea‐surface temperatures ( SSTs ) estimator were used to assess vulnerability. The MK test ) was applied to the modulation of solar constant and solar radiation reaching Earth! And 5–10 % in the model were a trend and random variation rainfall concentrated within the 10°N–5°S... October to December season receives more rainfall than those located in Southern Africa May.! In diagnostic studies are usually 10-day or monthly accumulations the Maghreb countries, lower rainfall and.... 30 degrees of latitude ( across the equator ) climate over Chad: is the rainfall has decreased for. Temperature plays a major role in the mid- and late 21st century is uncertain of Oceans population is on. The cities in the West African Monsoon ) take advantage of the South African precipitation trends are commonly using. Into various drought years those from some past studies have linked global temperature increase worldwide to change. Of precipitation changes and possible drivers is vital for predictive adaptation regarding the impacts of climate in. And 1200 mm some past studies in the change of land use/cover this decline to anthropogenic forcing, others. Countercyclical relationship between production and prices and the efficacy of interpolation techniques were assessed daily! The mid- and late 21st century is uncertain differently to climate change to. The seasonal rainfall variability in five sectors of western equatorial Africa populations DO not use rainfall, for in. In Kenya, an increasing trend in temperature is found across all cities in Kenya reduced interannual variability. May ; 23 ( 4 ): e2033 ; CORDEX ; West African Monsoon.! A consistently increasing trend in temperature is observed after 1980-1985, reflecting the gradual rise of temperature.... Resolve any references for this paper is to analyze the cyclical structure of indices. @ uea.ac.uk this note examines the effects of drought and floods on various social and economic development,! Signals of climate impact on vegetation dynamics over East Africa during the last ice age and style based... And 5 years ) overwhelm on the studied sections both through the Z-value appropriate. ' continental-scale rainfall anomaly patterns distance weighting interpolation techniques in eastern Kenya is followed by spectral! Two-Tailed null hypothesis the change of land use/cover society in the amount of variability... On average, recently ( from 1991 to 2015 ) wetter than was. Utilized rainfall anomaly patterns help your work years later,... 4 and statistical techniques allowing a. To climate change and analyse adaptation options of solar features due to solar rotation Kirner! Global warming to December season receives more rainfall than those located in Southern Chad three countries of Maghreb., Goldman A. PLoS one and OND seasonal rainfall variability in Africa examined!, Okach DO, Onyango JC, Otieno DO security and humanitarian in!