Download or read book Historical Variability of Rainfall in the African East Sahel of Sudan written by John F. Hermance and published by Springer Science & Business Media. This book was released on 2013-09-03 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: The northward migration of the African monsoon rains in summer, associated with the seasonal march of the Intertropical Convergence Zone (ITCZ) across the plains south of the Sahara, is the most critical asset for the livelihoods of indigenous peoples and local economies of the Sahel. It is essential that climate science (and its publicly available database) play a key role in characterizing the variabilities of these rainfall patterns in space and time if sustainable life styles are to accommodate the expanding populations of the region. This study turns to the East Sahel of Sudan by analyzing over 100 years of historical rainfall data from three of the few long term standard WMO rain gauge stations in substantially different rainfall settings. From north to south, transecting the Sahel, the stations with their annual rainfall are Khartoum (130 mm); Kassala (280 mm); and Gedaref (600 mm). The conclusions challenge a popular notion that changing climate, drought and desertification in the East Sahel may have already accelerated the deterioration of its water resources. However, any evidence of a persistent and coherent regional trend of diminishing rainfall is obscure. Quite the contrary, the evidence demonstrates that the fluctuations of climate and weather patterns over the ensuing decades of the past century - at all temporal scales from days to years to decades - profoundly overwhelm any suggestion of a large-scale, coherent decrease (or increase) in rainfall. The implication is that, it is not long term change, but the highly localized interseasonal, interannual and multiannual variability of rainfall that poses the greatest and most immediate societal threat from naturally-induced causes; a process constantly destabilizing an agrarian economy struggling to survive in a climate that irregularly vacillates between years of drought and years of flooding. While this report may have some interest for climate scientists, it is primarily directed to a general readership (including students in public policy and anthropology) concerned with the availability of water in the Sahel, particularly the long term sustainability of local small-scale farms and transhumant pastoralism.

Download or read book Climate change and agriculture in the Sudan Impact pathways beyond changes in mean rainfall and temperature written by Siddig, Khalid and published by Intl Food Policy Res Inst. This book was released on 2018-09-26 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several environmental changes have occurred in the Sudan in the past; several are ongoing; and others are projected to happen in the future. The Sudan has witnessed increases in temperature, floods, rainfall variability, and concurrent droughts. In a country where agriculture, which is mainly rainfed, is a major contributor to gross domestic product, foreign exchange earnings, and livelihoods, these changes are especially important, requiring measurement and analysis of their impact. This study not only analyzes the economy-wide impacts of climate change, but also consults national policy plans, strategies, and environmental assessments to identify interventions which may mitigate the effects. We feed climate forcing, water demand, and macro-socioeconomic trends into a modelling suite that includes models for global hydrology, river basin management, water stress, and crop growth, all connected to the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT). The outcomes of this part of the modeling suite are annual crop yields and global food prices under various climate change scenarios until 2050. The effects of such changes on production, consumption, macroeconomic indicators, and income distribution are assessed using a single country dynamic Computable General Equilibrium (CGE) model for the Sudan. Additionally, we introduce yield variability into the CGE model based on stochastic projections of crop yields until 2050. The results of the model simulations reveal that, while the projected mean climate changes bring some good news for the Sudan, extreme negative variability costs the Sudan cumulatively between 2018 and 2050 US$ 109.5 billion in total absorption and US$ 105.5 billion in GDP relative to a historical mean climate scenario without climate change.

Download or read book Mechanisms of East African Rainfall Variability written by Buruhani Salum Nyenzi and published by . This book was released on 1988 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Annotated Bibliography of the Climate of Sudan written by and published by . This book was released on 1987 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Understanding Precipitation Variability Over Africa written by Weiran Liu (Ph. D.) and published by . This book was released on 2019 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding precipitation variability over Africa is important because this region experiences rainfall events that influence agriculture and economic infrastructure, and threaten lives regularly. This study aims to advance our understanding of African precipitation across different timescales, from diurnal cycle to interannual variations, using observations, reanalyses, and regional climate model simulations. First, we evaluate the role of MCSs in the total rainfall distribution as a function of season from a climatological perspective (1998-2014) over sub-Saharan northern Africa and examine how the diurnal cycle of rainfall changes with season. The percentages of the full TRMM precipitation delivered by MCSs have meridional structures in spring, fall and winter, while the percentages are homogenous in summer (>80%). The diurnal peaks are classified into three categories: single afternoon peak, continuous afternoon peak, and nocturnal peak. The continuous afternoon peak combines rainfall from two system types –one locally-generated and one propagating. The seasonality of the diurnal cycle is related to the seasonality of MCS lifetimes, and propagation speeds and directions. Second, a low-level jet, the West African westerly jet, is investigated over the West African coast. In the western Sahel (0°-10°W, 8°-18°N), the moisture flux associated with the jet is stronger than that associated with the southerly West African monsoon flow from July 5 to August 20 (45 days). The moisture budget analysis reveals that the seasonal evolution of the rainfall in this analysis region is associated with zonal moisture convergence related to changes of the jet. Finally, three sub-regions of the Indian Ocean in which SSTs significantly influence the equatorial East African short rains on interannual timescales are identified, and the physical processes of this influence are studied using regional climate model simulations. SSTAs in the western Indian Ocean exert a stronger influence on the short rains than central and eastern Indian Ocean SSTAs both in terms of the coverage of significantly-changed precipitation and the magnitude of the precipitation response. The mechanisms of this influence are diagnosed using atmospheric moisture budget and moist static energy analyses, with reference to Kelvin and Rossby wave generation as in the Gill model, but in the presence of complicated topography and nonzero background flows

Download or read book Aerosol and Rainfall Variability Over the Northern African Sahel written by Eskender Girmay and published by LAP Lambert Academic Publishing. This book was released on 2015-02-16 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this study is to show the link between African Aerosol and Rainfall variability in the North African Sahel. In this study, I use more recent satellite data of high resolution and quality to investigate the extent to which the observed large-scale relationship between the two can be interpreted as an aerosol effect on precipitation. I want to list out the main objectives as follows: To show the relationship between Aerosols, water vapor and rainfall in the Northern African Sahel. Using statistical methods of correlation and regression (forecast) by taking a 6-month time lag, which is the most appropriate time lag that we found after repeated checking of the correlation factor R. To check out the forecasted value of rain fall in the year 2002 using a predictor of the four parameters (total optical depth, dust, anthropogenic and fine mode aerosols)to identify the major types of aerosols that contributes the precipitation variability over the Northern African Sahel. To show the seasonal distribution of aerosols (by plotting their time series), this leads to seasonal variability of precipitation over the northern African Sahel.

Download or read book Meteorology of Tropical West Africa written by Douglas J. Parker and published by John Wiley & Sons. This book was released on 2017-04-24 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: Meteorology of tropical West Africa: the Forecasters’ Handbook presents the science and practice of weather forecasting for an important region of the tropics. Connecting basic theory with forecasting practice, the book provides a unique training volume for operational weather forecasters, and is also suitable for students of tropical meteorology. The West African region contains a number of archetypal climatic zones, meaning that the science of its weather and climate applies to many other tropical regions. West Africa also exhibits some of the world’s most remarkable weather systems, making it an inspiring region for students to investigate. The weather of West Africa affects human livelihoods on a daily basis, and can contribute to hardship, poverty and mortality. Therefore, the ability to understand and predict the weather has the potential to deliver significant benefits to both society and economies. The book includes comprehensive background material alongside documentation of weather forecasting methods. Many examples taken from observations of West African weather systems are included and online case-studies are referenced widely.

Download or read book The Hadley Circulation Present Past and Future written by Henry F. Diaz and published by Springer Science & Business Media. This book was released on 2007-11-05 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book examines potentially important factors that may have affected the Hadley and Walker Circulations and evaluates changes in the Hadley Circulation and the monsoons as simulated by coupled models of past climate conditions, and predicted future conditions under an enhanced greenhouse effect. This book is meant to serve as a fundamental reference work for current and future researchers, graduate students in the atmospheric sciences and geosciences, and climate specialists involved in interdisciplinary research.

Download or read book Climate Science for Serving Society written by Ghassem R. Asrar and published by Springer Science & Business Media. This book was released on 2013-06-18 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume offers a comprehensive survey and a close analysis of efforts to develop actionable climate information in support of vital decisions for climate adaptation, risk management and policy. Arising from submissions and discussion at the 2011 Open Science Conference (OSC) of the World Climate Research Program (WCRP), the book addresses research and intellectual challenges which span the full range of Program activities.

Download or read book Drivers and Mechanisms of Historical Sahel Precipitation Variability written by Rebecca Jean Herman and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter lays the foundation for future work to fully-characterize the dependence of Sahel precipitation on individual ocean basins using the non-targeted simulations already available in CMIP - an approach which can be validated by comparing the composite results to the interventional historical simulations that are available. Furthermore, we hope this chapter will guide algorithm improvement efforts that are needed to increase the performance and usefulness of time series causal discovery algorithms on climate data.

Download or read book Rainfall Variability and Drought in Sub Saharan Africa Since 1960 written by René A. Gommes and published by . This book was released on 1994 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Roots in the African Dust written by Michael Mortimore and published by Cambridge University Press. This book was released on 1998-09-17 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: The image of Africa in the modern world has come to be shaped by perceptions of the drylands and their problems of poverty, drought, degradation, and famine. Michael Mortimore offers an alternative and revisionist thesis, dismissing on theoretical and empirical grounds the conventional view of runaway desertification, driven by population growth and inappropriate land use. In its place he suggests a more optimistic model of sustainable land use, based on researched case studies from East and West Africa where indigenous technological adaptation has put population growth and market opportunities to advantage. He also proposes a more appropriate set of policy priorities to support dryland peoples in their efforts to sustain land and livelihoods. The result is a remarkably clear synthesis of much of the best work that has emerged over past years.

Download or read book Environmental Controls on African Rainfall Variability written by Siyu Zhao and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Local African communities heavily depend on rain-fed agriculture, which are vulnerable to the impacts of extreme weather and climate variability/change. However, challenges remain in predicting African rainfall. For instance, climate models with cumulus convective parametrization lack the ability to explicitly simulate mesoscale convective systems that produce much of the total rainfall over West Africa. This study aims to improve our understanding of African rainfall variability, using state-of-the-art rainfall observations and convective-permitting (CP) ensemble simulations. This work is organized into three research projects. In the first project, we evaluate the influence of Walker circulations on East African Rainfall. Three Walker circulations are identified near East Africa, namely, the East African, the Indian Ocean, and the Congo Basin Walker Circulations. Less (more) precipitation occurs over equatorial East Africa during October – December with a strong (weak) Indian Ocean Walker Circulation. The rainfall anomalies are associated with anomalous mid-level divergence over equatorial East Africa that is likely induced by horizontal moist static energy advection. In the second project, we investigate how the observed shrinkage of Lake Chad since the 1970s affects the local climate using CP simulations. A smaller lake area enhances the local precipitation by limiting the spatial extent of daytime lake breezes, which would otherwise induce low-level subsidence/divergence and suppress local afternoon rainfall. In addition, a shallow planetary boundary layer over the large lake weakens turbulent vertical mixing, reducing low- to mid-level humidity and the likelihood of convection triggering compared to the small lake. In the third project, we analyze the roles of thermodynamic and dynamic controls on intense storms over the West African Sahel with climate change. Future-Warming simulations are run with initial/boundary conditions prescribed by the current-climate data plus CMIP6 multi-model mean anomalies. The 99th (99.9th) 24-hr precipitation increases from 42 (77) mm in the current climate to 59 (104) mm in the future over the analysis region (12°N-18°N, 9°W-20°E). Increased low-tropospheric moisture (gradient) is more closely associated with this rainfall intensification than enhanced low- to mid- level vertical wind shear. Both moisture and shear conditions are related to the storm area and propagating speed that affect local rainfall accumulation

Download or read book Meteorological Drought written by Wayne C. Palmer and published by . This book was released on 1965 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: The underlying concept of the paper is that the amount of precipitation required for the near-normal operation of the established economy of an area during some stated period is dependent on the average climate of the area and on the prevailing meteorological conditions both during and preceding the month or period in question. A method for computing this required precipitation is demonstrated.

Download or read book Population Size Concentration and Civil War written by Håvard Hegre and published by World Bank Publications. This book was released on 2007 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Why do larger countries have more armed conflict? This paper surveys three sets of hypotheses forwarded in the conflict literature regarding the relationship between the size and location of population groups: Hypotheses based on pure population mass, on distances, on population concentrations, and some residual state-level characteristics. The hypotheses are tested on a new dataset-ACLED (Armed Conflict Location and Events Dataset)-which disaggregates internal conflicts into individual events. The analysis covers 14 countries in Central Africa. The conflict event data are juxtaposed with geographically disaggregated data on populations, distance to capitals, borders, and road networks. The paper develops a statistical method to analyze this type of data. The analysis confirms several of the hypotheses.

Download or read book East African Ecosystems and Their Conservation written by T. R. McClanahan and published by Oxford University Press, USA. This book was released on 1996 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: East Africa is one of the most diverse and interesting tropical area on the planet. It is home not only to the last great megafaunal assemblage, but also to human populations with the highest growth rates. This book draws on the expertise of leading ecologists, each intimately familiar with a particular set of East African ecosystems, to provide the first in-depth and integrated account of the ecology, management, threats, and conservation of these diverse ecosystems. Summarizing the tremendous wealth of scientific research that has come out of East Africa in the last few decades, each chapter analyzes a given ecosystem type, taking the reader through the basics of its ecology, its historical use (and misuse) by humans, and its prospects for conservation. Throughout the book, linkages and similarities among ecosystems are emphasized, the historical and contemporary role of humans in shaping these ecosystems is considered, fundamental principles of ecology are considered, and interesting case studies are highlighted. Students and researchers in ecology, conservation biology, and environmental sciences will find this book useful in their work.

Download or read book Adaptation to Climate Change and Variability in Rural West Africa written by Joseph A. Yaro and published by Springer. This book was released on 2016-04-12 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents conceptual and empirical discussions of adaptation to climate change/variability in West Africa. Highlighting different countries’ experiences in adaptation by different socio-economic groups and efforts at building their adaptive capacity, it offers readers a holistic understanding of adaptation on the basis of contextual and generic sources of adaptive capacity. Focusing on adaptation to climate change/variability is critical because the developmental challenges West Africa faces are increasingly intertwined with its climate history. Today, climate change is a major developmental issue for agrarian rural communities with high percentages of the population earning a living directly or indirectly from the natural environment. This makes them highly vulnerable to climate-driven ecological change, in addition to threats in the broader political economic context. It is imperative that rural people adapt to climate change, but their ability to successfully do so may be limited by competing risks and vulnerabilities. As such, elucidating those vulnerabilities and sources of strength with regard to the adaptive capacities needed to support successful adaptation and avoid maladaptation is critical for future policy formulation. Though the empirical discussion is geographically based on West Africa, its applicability in terms of the processes, structures, needs, strategies, and recommendations for policy transcends the region and provides useful lessons for understanding adaptation broadly in the developing world.