Understanding Rainfall Variability Over West Africa and Climate Sensitivity in the Tropics PDF Download

Author: Gang Zhang (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 135

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Book Description
West African rainfall plays an important role in tropical climate and hydrological cycle. This study aims to advance our understanding of the West African rainfall across different timescales, from the diurnal cycle to interannual variations. Then, the study is extended to understand the climate sensitivity in the tropics with an increase of greenhouse gases. First, on a short timescale, the diurnal cycle of warm season rainfall over West Africa is investigated. In both the climatology and the 2006 case study, most of West Africa shows a single diurnal peak of rainfall in either the afternoon or at night. Afternoon rainfall peaks are associated with an unstable lower troposphere. Nocturnal rainfall peaks are associated with rainfall systems propagating westward. They occur most frequently about 3°-10° of longitude downstream of regions with afternoon rainfall peaks. Rainfall systems in the convection-permitting simulation show similar westward propagation with afternoon peaks associated with elevated topography and nocturnal peaks downstream of the topographic afternoon rainfall regions. However, the model fails to reproduce the observed afternoon rainfall peaks in several regions far away from the downstream of elevated topography. Second, on a longer timescale, the climatology and interannual variations of the West African monsoon demise are investigated using the Tropical Rainfall Measuring Mission and the Global Precipitation Climatology Project precipitation datasets along with the ERA-Interim reanalysis. During monsoon demise, the rainfall maximum progresses southward smoothly from the Sahel to the Gulf of Guinea. The climatological monsoon demise date is October 20th. The demise date varies between October 5th and 30th. An early (late) demise is associated with an anomalously strong (weak) North Atlantic subtropical high. The monsoon season total rainfall is found to be significantly correlated with the demise date. Finally, idealized regional model simulations are used to understand the climate sensitivity over the broad tropical region. The model is configured with idealized continents and oceans. With a doubling of CO2, the land and the ocean warm at different rates. The changes of the continental heat lows, subtropical highs and land-based rainfall in the tropics are explored and linked to the surface warming.

Author: Julián Villamayor
Publisher: Springer
ISBN: 3030203271
Category : Science
Languages : en
Pages : 227

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Book Description
In this book the Sea Surface Temperature (SST) patterns of decadal-to-multidecadal variability observed and simulated by 17 general circulation models (GCMs) are analyzed. Furthermore, their impact on precipitation in West Africa and South America and the atmospheric mechanisms involved are assessed. Through this analysis, the effect of external forcings on these impacts and the relative contribution of decadal-to-multidecadal variability patterns of SST to precipitation are presented in depth. Finally, a humid period in the West African region of the Sahel during the 19th century, previously little documented, is analyzed using an atmospheric GCM. The monsoons of West Africa and South America have shown changes in the timescales of a few decades. Previous work suggests a relationship with patterns of decadal-to-multidecadal variability of SST, such as global warming and the Atlantic and Pacific variability. However, the dynamics underlying this relationship and its simulation by current GCMs had not been addressed in a consistent manner. This is the main motivation of this book. The results of this book not only represent a great step forward in our understanding of the changes in the precipitation regimes of the studied regions, but they can also be of great help for the improvement of decadal prediction systems and the associated social consequences.

Author: Charles J. R. Williams
Publisher: Springer Science & Business Media
ISBN: 9048138426
Category : Science
Languages : en
Pages : 204

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Book Description
Compared to many other regions of the world, Africa is particularly vulnerable to the effects of climate change and variability. Widespread poverty, an extensive disease burden and pockets of political instability across the continent has resulted in a low resilience and limited adaptative capacity of African society to climate related shocks and stresses. To compound this vulnerability, there remains large knowledge gaps on African climate, manifestations of future climate change and variability for the region and the associated problems of climate change impacts. Research on the subject of African climate change requires an interdisciplinary approach linking studies of environmental, political and socio-economic spheres. In this book we use different case studies on climate change and variability in Africa to illustrate different approaches to the study of climate change in Africa from across the spectrum of physical, social and political sciences. In doing so we attempt to highlight a toolbox of methodologies (along with their limitations and advantages) that may be used to further the understanding of the impacts of climate change in Africa and thus help form the basis for strategies to negate the negative implications of climate change on society.

Author: Joseph A. Yaro
Publisher: Springer
ISBN: 3319314998
Category : Science
Languages : en
Pages : 249

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Book Description
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.

Author: Douglas J. Parker
Publisher: John Wiley & Sons
ISBN: 1118391306
Category : Science
Languages : en
Pages : 490

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Book Description
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.

Author: A.J. Dietz
Publisher: Springer Science & Business Media
ISBN: 1402021585
Category : Science
Languages : en
Pages : 467

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Book Description
Sahelian West Africa has recovered from the disastrous droughts of the 1970s and 1980s. People have learned to adapt to risk and uncertainty in fragile dryland environments. They, as well as global change scientists, are worried about the impact of climate change on these West African drylands. What do the experiences of the last thirty years say about the preparedness for higher temperatures, lower rainfall, and even more variability? Detailed studies on Dryland West Africa as a whole, and on Burkina Faso, Mali and Northern Ghana in particular show an advanced coping behaviour and increased adaptation, but also major differences in vulnerability and coping potential. Climate change preparedness programmes have only just started and require more robust support, and more specific social targeting, for a population which is rapidly growing, even more rapidly urbanising, and further integrating in a globalised economy. This book is the first of its kind with a comprehensive analysis of climate change experiences in West African drylands, with attention for pathways of change and the diversity of adaptation options available. This book is of interest to scientists studying global and climate change, especially dealing with issues of adaptation. Social scientists, economists, geographers and policy makers concerned with West Africa should also read this book.

Author: Weiran Liu (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 320

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Book Description
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

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 6

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Book Description
The purpose of the proposed project is to improve our understanding of the physical processes and large-scale connectivity of changes in intense precipitation events (high rainfall rates) under global warming in West Africa and the central U.S., including relationships with low-frequency modes of variability. This is in response to the requested subject area #2 "simulation of climate extremes under a changing climate ... to better quantify the frequency, duration, and intensity of extreme events under climate change and elucidate the role of low frequency climate variability in modulating extremes." We will use a regional climate model and emphasize an understanding of the physical processes that lead to an intensification of rainfall. The project objectives are as follows: 1. Understand the processes responsible for simulated changes in warm-season rainfall intensity and frequency over West Africa and the Central U.S. associated with greenhouse gas-induced global warming 2. Understand the relationship between changes in warm-season rainfall intensity and frequency, which generally occur on regional space scales, and the larger-scale global warming signal by considering modifications of low-frequency modes of variability. 3. Relate changes simulated on regional space scales to global-scale theories of how and why atmospheric moisture levels and rainfall should change as climate warms.

Author: Assefa M. Melesse
Publisher: Elsevier
ISBN: 0128159995
Category : Science
Languages : en
Pages : 580

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Book Description
Extreme Hydrology and Climate Variability: Monitoring, Modelling, Adaptation and Mitigation is a compilation of contributions by experts from around the world who discuss extreme hydrology topics, from monitoring, to modeling and management. With extreme climatic and hydrologic events becoming so frequent, this book is a critical source, adding knowledge to the science of extreme hydrology. Topics covered include hydrometeorology monitoring, climate variability and trends, hydrological variability and trends, landscape dynamics, droughts, flood processes, and extreme events management, adaptation and mitigation. Each of the book's chapters provide background and theoretical foundations followed by approaches used and results of the applied studies. This book will be highly used by water resource managers and extreme event researchers who are interested in understanding the processes and teleconnectivity of large-scale climate dynamics and extreme events, predictability, simulation and intervention measures. Presents datasets used and methods followed to support the findings included, allowing readers to follow these steps in their own research Provides variable methodological approaches, thus giving the reader multiple hydrological modeling information to use in their work Includes a variety of case studies, thus making the context of the book relatable to everyday working situations for those studying extreme hydrology Discusses extreme event management, including adaption and mitigation

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
The Volta Basin is a climate sensitive, semi-arid to sub-humid region in West Africa. Livelihood of the population is mainly dependent on agriculture and therefore highly vulnerable to rainfall variability and climate change. For an investigation of the impact of a possible global climate change to regional climate and surface, as well as sub-surface hydrology in the region of the Volta Basin, coupled regional climate-hydrology simulations were performed. Therefore, the mesoscale meteorological model MM5 was set up, fully coupled to a 1-dimensional SVAT (Soil Vegetation Atmosphere Transfer) model, to account for soil-atmosphere feedback mechanisms. After a validation was performed, MM5 was used as a regional climate model to simulated two 10-years time slices: 1991-2000 and 2030-2039. The emission scenario IS92a output of the global climate model ECHAM4 was downscaled dynamically, to a final resolution of 9km, for the Volta Basin. These regional climate simulations were then coupled to the physically based, distributed hydrological model WaSiM, after the calibration and adaptation of the hydrological model to the study region. A comparison the GCM output, as well as the RCM output for present-day climate simulation to observations showed a wet bias over the Sahel and a sufficient accuracy in temperature representation for the ECHAM4, present-day simulation (1961-1990). In the regional climate simulations, the displacement of the Inter Tropical Discontinuity (ITD) to the North at the beginning of the rainy season, as well as the displacement South, at the end occur too early. Rainfall also showed a negative deviation along the coast but a sufficient accuracy in the Volta Basin. The results of the MM5 and WaSiM simulations show an annual mean temperature increase by 1.2-1.3°C in West Africa and the Volta Basin. This temperature change significantly exceeds inter-annual variability. Mean annual precipitation increases for both, the sahelian and the coastal region of We.