A Two-Century Precipitation Dataset for the Continent of Africa

Nicholson, Sharon E.; Dezfuli, Amin; Klotter, Douglas

doi:10.1175/bams-d-11-00212.1

Cited by 112 publications

(92 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For the Sahel, vegetation lost during the drought of c. 1738-1756 may have become reestablished during c. 1760-1790, which was relatively humid with some evidence of appreciable flooding (50). If not, bistability implies that reestablishment would not have occurred until the next markedly humid period, which began in the mid-1800s, following an extended arid interval which began c. 1790 and included a notable drought c. 1828-1839 (47,50). This suggests that today's banded vegetation originated by colonization of bare ground either during c. 1760-1790, or since c. 1850.…”

Section: Discussionmentioning

confidence: 99%

Using wavelength and slope to infer the historical origin of semiarid vegetation bands

Sherratt

2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Landscape-scale patterns of vegetation occur worldwide at interfaces between semiarid and arid climates. They are important as potential indicators of climate change and imminent regime shifts and are widely thought to arise from positive feedback between vegetation and infiltration of rainwater. On gentle slopes the typical pattern form is bands (stripes), oriented parallel to the contours, and their wavelength is probably the most accessible statistic for vegetation patterns. Recent field studies have found an inverse correlation between pattern wavelength and slope, in apparent contradiction with the predictions of mathematical models. Here I show that this “contradiction” is based on a flawed approach to calculating the wavelength in models. When pattern generation is considered in detail, the theory is fully consistent with empirical results. For realistic parameters, degradation of uniform vegetation generates patterns whose wavelength increases with slope, whereas colonization of bare ground gives the opposite trend. Therefore, the empirical finding of an inverse relationship can be used, in conjunction with climate records, to infer the historical origin of the patterns. Specifically, for the African Sahel my results suggest that banded vegetation originated by the colonization of bare ground during circa 1760–1790 or since circa 1850.

show abstract

Section: Discussionmentioning

confidence: 99%

Using wavelength and slope to infer the historical origin of semiarid vegetation bands

Sherratt

2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Stebbing (1935Stebbing ( , 1938 and others interpreted the post-drought situation as a desert encroachment, thus misleading future scientists. The first drought period in the past century lasted from 1909-1915(Nicholson, 2012 but the early researchers neglected the fact that the data for such a short time span would rather indicate only climatic fluctuations instead of real climatic crisis (Mainguet, 1991).…”

Section: Contributions Of Other Authorsmentioning

confidence: 99%

“…Scattered vegetation or "mode diffuse" refers to a more continuous vegetation cover on different soil types and is representative of savanna systems (Monod, 1954). Nicholson et al (2012) provide a semi-quantitative precipitation dataset for the 19th century, adding these data to the more modern gauge data. According to their findings a severe and long-lasting drought could be documented for the beginning of the 19th century followed by a moderate recovery in rainfall mixed with some dry years.…”

Section: Introductionmentioning

confidence: 99%

Desertification, resilience, and re-greening in the African Sahel – a matter of the observation period?

Kusserow

2017

Earth Syst. Dynam.

View full text Add to dashboard Cite

Abstract. Since the turn of the millennium various scientific publications have been discussing a re-greening of the Sahel after the 1980s drought mainly based on coarse-resolution satellite data. However, the author's own field studies suggest that the situation is far more complex and that both paradigms, the "encroaching Sahara" and the "re-greening Sahel", need to be questioned. This paper discusses the concepts of desertification, resilience, and re-greening by addressing four main aspects: (i) the relevance of edaphic factors for a vegetation re-greening, (ii-iii) the importance of the selected observation period in the debate on Sahel greening or browning, and (iv) modifications in the vegetation pattern as possible indicators of ecosystem changes (shift from originally diffuse to contracted vegetation patterns).The data referred to in this paper cover a time period of more than 150 years and include the author's own research results from the early 1980s until today. A special emphasis, apart from fieldwork data and remote sensing data, is laid on the historical documents.The key findings summarised at the end show the following: (i) vegetation recovery predominantly depends on soil types; (ii) when discussing Sahel greening vs. Sahel browning, the majority of research papers only focus on post-drought conditions. Taking pre-drought conditions (before the 1980s) into account, however, is essential to fully understand the situation. Botanical investigations and remote-sensing-based time series clearly show a substantial decline in woody species diversity and cover density compared to pre-drought conditions; iii) the self-organised patchiness of vegetation is considered to be an important indicator of ecosystem changes.

show abstract

“…The dramatic changes that occurred over Sahelian Africa from wet conditions in the 1950s to much drier conditions in the 1970s-1980s to be followed by partial recovery after the 1980s represent one of the strongest interdecadal climate variabilities and the longest drought on the planet in the twentieth century (e.g., Redelsperger et al 2007; Lebel and Ali 2009;Nicholson et al 2012). A significant climate feature in Sahelian Africa is the West African monsoon (WAM), which exerts a strong control on climate variability in the Sahel.…”

Section: Introductionmentioning

confidence: 99%

West African monsoon decadal variability and surface-related forcings: second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II)

et al. 2016

View full text Add to dashboard Cite

in the Sahel climate system at seasonal to decadal scales. The project's strategy is to apply prescribed observationally based anomaly forcing, i.e., "idealized but realistic" forcing, in simulations by climate models. The goal is to assess these forcings' effects in producing/amplifying seasonal and decadal climate variability in the Sahel between the 1950s and the 1980s, which is selected to characterize the great drought period of the last century. This is the first multi-model experiment specifically designed to simultaneously evaluate such relative contributions. The WAMME II models have consistently demonstrated that SST forcing is a major contributor to the twentieth century Sahel drought. Under the influence of the maximum possible SST forcing, the ensemble mean of WAMME II models can produce up to 60 % of the precipitation difference during the period. The present paper also addresses the role of SSTs Abstract The second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II) is designed to improve understanding of the possible roles and feedbacks of sea surface temperature (SST), land use land cover change (LULCC), and aerosols forcings This paper is a contribution to the special issue on West African climate decadal variability and its modeling, consisting of papers from the West African Monsoon Modeling and Evaluation (WAMME) and the African Multidisciplinary Monsoon Analyses (AMMA) projects, and coordinated by Yongkang Xue, Serge Janicot, and William Lau. Provided Funding information has to be tagged. Electronic supplementary materialThe online version of this article (doi:10.1007/s00382-016-3224-2) contains supplementary material, which is available to authorized users. 3in triggering and maintaining the Sahel drought. In this regard, the consensus of WAMME II models is that both Indian and Pacific Ocean SSTs greatly contributed to the drought, with the former producing an anomalous displacement of the Intertropical Convergence Zone before the WAM onset, and the latter mainly contributes to the summer WAM drought. The WAMME II models also show that the impact of LULCC forcing on the Sahel climate system is weaker than that of SST forcing, but still of first order magnitude. According to the results, under LULCC forcing the ensemble mean of WAMME II models can produces about 40 % of the precipitation difference between the 1980s and the 1950s. The role of land surface processes in responding to and amplifying the drought is also identified. The results suggest that catastrophic consequences are likely to occur in the regional Sahel climate when SST anomalies in individual ocean basins and in land conditions combine synergistically to favor drought.Keywords Sahel seasonal and decadal climate variability · Sahel drought, SST and land forcings · GCM

show abstract

A Two-Century Precipitation Dataset for the Continent of Africa

Abstract: a semiquantitative precipitation dataset for the nineteenth century to add to the more modern gauge data.

Cited by 112 publications

References 26 publications

Using wavelength and slope to infer the historical origin of semiarid vegetation bands

Using wavelength and slope to infer the historical origin of semiarid vegetation bands

Desertification, resilience, and re-greening in the African Sahel – a matter of the observation period?

West African monsoon decadal variability and surface-related forcings: second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II)

Contact Info

Product

Resources

About