Study of the Occurrence of Extreme Precipitation and Droughts in Northern Africa: Estimation of Return Periods and Return Levels
The occurrence of extreme hydro-climatic events such as floods and severe droughts has adverse impacts on society and economy of African countries, especially those of south of the Sahara, because of their low levels of development, which is associated with the high vulnerability of their population...
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Language: | French |
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2020
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ftccsdartic:oai:HAL:tel-03421091v1 2023-05-15T17:37:12+02:00 Study of the Occurrence of Extreme Precipitation and Droughts in Northern Africa: Estimation of Return Periods and Return Levels Etude de l’Occurrence des Précipitations et des Sécheresses Extrêmes en Afrique au Nord de l’Équateur : Estimation des Périodes de Retour et des Niveaux de Retour Chamani, Roméo Département de physique (Faculté des sciences, Université de Yaoundé 1) Faculté des Sciences - Yaoundé I Université de Yaoundé I-Université de Yaoundé I Université de Douala David Monkam 2020-09-01 https://hal.archives-ouvertes.fr/tel-03421091 https://hal.archives-ouvertes.fr/tel-03421091/document https://hal.archives-ouvertes.fr/tel-03421091/file/Memoire_these_de_Doctorat_Chamani.pdf fr fre HAL CCSD tel-03421091 https://hal.archives-ouvertes.fr/tel-03421091 https://hal.archives-ouvertes.fr/tel-03421091/document https://hal.archives-ouvertes.fr/tel-03421091/file/Memoire_these_de_Doctorat_Chamani.pdf info:eu-repo/semantics/OpenAccess https://hal.archives-ouvertes.fr/tel-03421091 Physique [physics]. Université de Douala, 2020. Français northern Africa Sahel extreme rainfall extreme drought return period return level extreme value theory large-scale modes of climate variability Afrique au Nord de l’Équateur précipitations extrêmes sécheresses extrêmes périodes de retour niveaux de retour théorie des valeurs extrêmes variabilité climatique à grande échelle [PHYS]Physics [physics] info:eu-repo/semantics/doctoralThesis Theses 2020 ftccsdartic 2021-12-11T23:43:55Z The occurrence of extreme hydro-climatic events such as floods and severe droughts has adverse impacts on society and economy of African countries, especially those of south of the Sahara, because of their low levels of development, which is associated with the high vulnerability of their populations. A study that analyzes their occurrence and their evolution, for the forecasting purposes, is a necessity for the region. This thesis focuses on the occurrence of the July–September (JAS) extreme rainfall and droughts in the northern Africa. Specifically, it addresses the issue of modeling their occurrences, estimating their return periods (RP) and their return levels (RL) in the context of stationary and non-stationary climate, and to evaluate the influence of the large-scale modes of climate variability (L-SMCV) on both their occurrence and the intensity of their RL. To conduct this investigation, we used monthly rainfall data from the Climatic Research Unit of the University of East Anglia in England, over the period 1901–2014; and those of four climate indices—the El Niño southern oscillation, the North Atlantic oscillation, the Pacific decadal oscillation, and the Atlantic multi-decadal oscillation—from the Global Climate Observing System Working Group on Surface Pressure. Two classical statistical approaches derived from the extreme value theory were used to identify and model the JAS extreme hydro-climatic events in the northern Africa: the peaks-over-threshold approach, which models the excesses above the threshold according to a generalized Pareto distribution, and the block maxima approach, which supposes that the maxima follow a distribution of generalized extreme value. The results reveal a good fit between these statistical approaches and the JAS extremes—wet and dry extremes—across the northern Africa. It appears that the areas with high occurrences of JAS extreme rainfall for a fixed RP are those of Guinean coastal regions and those of highlands on the mainland. In general, over most northern Africa, ... Doctoral or Postdoctoral Thesis North Atlantic North Atlantic oscillation Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Pacific Retour ENVELOPE(141.558,141.558,-66.764,-66.764) |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
French |
topic |
northern Africa Sahel extreme rainfall extreme drought return period return level extreme value theory large-scale modes of climate variability Afrique au Nord de l’Équateur précipitations extrêmes sécheresses extrêmes périodes de retour niveaux de retour théorie des valeurs extrêmes variabilité climatique à grande échelle [PHYS]Physics [physics] |
spellingShingle |
northern Africa Sahel extreme rainfall extreme drought return period return level extreme value theory large-scale modes of climate variability Afrique au Nord de l’Équateur précipitations extrêmes sécheresses extrêmes périodes de retour niveaux de retour théorie des valeurs extrêmes variabilité climatique à grande échelle [PHYS]Physics [physics] Chamani, Roméo Study of the Occurrence of Extreme Precipitation and Droughts in Northern Africa: Estimation of Return Periods and Return Levels |
topic_facet |
northern Africa Sahel extreme rainfall extreme drought return period return level extreme value theory large-scale modes of climate variability Afrique au Nord de l’Équateur précipitations extrêmes sécheresses extrêmes périodes de retour niveaux de retour théorie des valeurs extrêmes variabilité climatique à grande échelle [PHYS]Physics [physics] |
description |
The occurrence of extreme hydro-climatic events such as floods and severe droughts has adverse impacts on society and economy of African countries, especially those of south of the Sahara, because of their low levels of development, which is associated with the high vulnerability of their populations. A study that analyzes their occurrence and their evolution, for the forecasting purposes, is a necessity for the region. This thesis focuses on the occurrence of the July–September (JAS) extreme rainfall and droughts in the northern Africa. Specifically, it addresses the issue of modeling their occurrences, estimating their return periods (RP) and their return levels (RL) in the context of stationary and non-stationary climate, and to evaluate the influence of the large-scale modes of climate variability (L-SMCV) on both their occurrence and the intensity of their RL. To conduct this investigation, we used monthly rainfall data from the Climatic Research Unit of the University of East Anglia in England, over the period 1901–2014; and those of four climate indices—the El Niño southern oscillation, the North Atlantic oscillation, the Pacific decadal oscillation, and the Atlantic multi-decadal oscillation—from the Global Climate Observing System Working Group on Surface Pressure. Two classical statistical approaches derived from the extreme value theory were used to identify and model the JAS extreme hydro-climatic events in the northern Africa: the peaks-over-threshold approach, which models the excesses above the threshold according to a generalized Pareto distribution, and the block maxima approach, which supposes that the maxima follow a distribution of generalized extreme value. The results reveal a good fit between these statistical approaches and the JAS extremes—wet and dry extremes—across the northern Africa. It appears that the areas with high occurrences of JAS extreme rainfall for a fixed RP are those of Guinean coastal regions and those of highlands on the mainland. In general, over most northern Africa, ... |
author2 |
Département de physique (Faculté des sciences, Université de Yaoundé 1) Faculté des Sciences - Yaoundé I Université de Yaoundé I-Université de Yaoundé I Université de Douala David Monkam |
format |
Doctoral or Postdoctoral Thesis |
author |
Chamani, Roméo |
author_facet |
Chamani, Roméo |
author_sort |
Chamani, Roméo |
title |
Study of the Occurrence of Extreme Precipitation and Droughts in Northern Africa: Estimation of Return Periods and Return Levels |
title_short |
Study of the Occurrence of Extreme Precipitation and Droughts in Northern Africa: Estimation of Return Periods and Return Levels |
title_full |
Study of the Occurrence of Extreme Precipitation and Droughts in Northern Africa: Estimation of Return Periods and Return Levels |
title_fullStr |
Study of the Occurrence of Extreme Precipitation and Droughts in Northern Africa: Estimation of Return Periods and Return Levels |
title_full_unstemmed |
Study of the Occurrence of Extreme Precipitation and Droughts in Northern Africa: Estimation of Return Periods and Return Levels |
title_sort |
study of the occurrence of extreme precipitation and droughts in northern africa: estimation of return periods and return levels |
publisher |
HAL CCSD |
publishDate |
2020 |
url |
https://hal.archives-ouvertes.fr/tel-03421091 https://hal.archives-ouvertes.fr/tel-03421091/document https://hal.archives-ouvertes.fr/tel-03421091/file/Memoire_these_de_Doctorat_Chamani.pdf |
long_lat |
ENVELOPE(141.558,141.558,-66.764,-66.764) |
geographic |
Pacific Retour |
geographic_facet |
Pacific Retour |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_source |
https://hal.archives-ouvertes.fr/tel-03421091 Physique [physics]. Université de Douala, 2020. Français |
op_relation |
tel-03421091 https://hal.archives-ouvertes.fr/tel-03421091 https://hal.archives-ouvertes.fr/tel-03421091/document https://hal.archives-ouvertes.fr/tel-03421091/file/Memoire_these_de_Doctorat_Chamani.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1766136977534484480 |