Bernard Fontaine

Bernard Fontaine
French National Centre for Scientific Research | CNRS · Laboratoire Biogéosciences, Dijon

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About

113
Publications
16,215
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3,368
Citations
Citations since 2016
0 Research Items
1278 Citations
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
Additional affiliations
September 1985 - present
French National Centre for Scientific Research
Position
  • Senior Researcher
Description
  • African monsoon, climate variability, climate change, West Africa

Publications

Publications (113)
Article
Full-text available
The Sahel experienced a severe drought during the 1970s and 1980s after wet periods in the 1950s and 1960s. Although rainfall partially recovered since the 1990s, the drought had devastating impacts on society. Most studies agree that this dry period resulted primarily from remote effects of sea surface temperature (SST) anomalies amplified by loca...
Article
Full-text available
This study systematically examines teleconnections between Atlantic sea surface temperature (SST) and the west–east distribution of Sahel rainfall throughout the 20th century, taking non-stationarity into account. Sahel rainfall variability of six selected rain gauges displays three dominant time-scales: multi-decadal (>20 year), quasi-decadal (8–1...
Article
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Four monthly rainfall patterns (RPs) describing four monthly typical recurrent rainfall spatial features over the Mediterranean area were computed with agglomerative hierarchical clustering: north-western Mediterranean (NWM), western and south-western Mediterranean (W&SM), Mediterranean generalized deficit (MGD) and north-eastern Mediterranean (NEM...
Article
Sahel rainfall shows pronounced decadal variability and a negative trend between wet conditions in the 1950s–1960s and dry ones in the 1970s–1980s. Using continuous wavelet transform the quasi-decadal variability (QDV) of rainfall reveals zonal contrasts. The highest QDV is identified in the 1950s–1960s over western Sahel and in the 1970s–1980s ove...
Conference Paper
Full-text available
West-African Sahel rainfall shows a large decadal signal, transitioning from wet conditions in the 1950s to dry conditions in the 1970s/80s. Only the quasi-decadal time-scale is significantly detected in the Sahel rainfall index during the 1970s and 1980s. This time-scale of rainfall variability appears to be related to two periods of dry condition...
Article
This study documents the time evolution of air temperature and heat waves occurrences over Northern Africa for the period 1979–2011. A significant warming (1°–3°C), appearing by the mid-1960s over Sahara and Sahel, is associated with higher/lesser frequency of warm/ cold temperatures, as with longer duration and higher occurrences of heat waves. He...
Article
Future climate changes in African regions are model-dependent and there is no consensus regarding Sahelian rainfall by the end of this century. Using 12 atmosphere-ocean global climate models of the third Coupled Model Intercomparison Project (CMIP3) we propose a multi-model (MM) analysis contrasting the 1960–1999 period (20c3m integration) and the...
Chapter
Full-text available
An exercise has been carried out to assess to what extent the Euro-Atlantic Weather Regimes (WR), described from the ERA-interim Reanalysis in the summer season, projects onto a pool of AGCMAMIP simulations in which sea surface temperatures (SST) are prescribed from observations. Although the model simulations present some biases in the spatial str...
Article
Full-text available
Although in the framework of the global climate research the Mediterranean climate variability and the West African Monsoon (WAM) dynamics have been considered for a long time as “passive” systems, i.e., prone to the influence of large scale ocean and atmospheric variability, over the last decade many studies have been dedicated to the WAM-Mediterr...
Article
The objective of the study was to evaluate the spatio-temporal impacts of seasonal rainfall and urban population growth on the variations in normalized difference vegetation index (NDVI) in north Cameroon, which includes climates from south to north, the Sudanese and Sahelian climates. To this end, 48 points of measured rainfall were interpolated b...
Article
This statistical study stresses the relationship between different types of thermal anomaly patterns observed in Mediterranean areas and rainfall amounts in the African and Indian monsoon regions at the inter‐decadal (>10 years), inter‐annual (10 d) and synoptic (3–9 d) scales through composite and correlation analyses performed on different atmosp...
Article
Full-text available
Cette synthèse rappelle quelques résultats à l’issue de l’expérience internationale AMMA (2003-2010) en matière de variabilité de la mousson africaine (des échelles intrasaisonnières à pluri-décennales) et de prospective climatique. Ceux-ci ont confirmé le poids des températures de surface marine et des téléconnexions pour les fluctuations interann...
Article
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Cet article fait le point sur certaines connaissances acquises dans le cadre du programme AMMA (phase 1) au sujet des impacts de la variabilité cli-matique sur la santé en Afrique de l'Ouest. Les auteurs ont travaillé d'une part sur les maladies sévissant majoritairement en saison des pluies, à vecteur tel que le paludisme à Plasmodium falciparum,...
Conference Paper
This study examines teleconnections between Atlantic SST and the west-east distribution of Sahel rainfall throughout the 20th century. Since the late 1960s, West African rainfalls have shown a pronounced negative trend over the Sahel. However, Sahel rainfall variability shows three coherent regions in West Africa: the Atlantic Coast (Dakar), centra...
Conference Paper
Full-text available
Low-frequency Sahel rainfall variability and Atlantic sea surface temperature during the last century. This study examines teleconnections between Atlantic SST and the west-east distribution of Sahel rainfall throughout the 20th century. Since the late 1960s, West African rainfalls have shown a pronounced negative trend over the Sahel. However, Sah...
Article
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[1] The accuracy of African Monsoon (AM) simulations together with expected future changes are presented using eight available CMIP5/AR5 AOGCMs under the RCP4.5 emission scenario and eight CMIP3/AR4 AOGCMs under the A1b scenario, with a multimodel approach and the “one model one vote” concept. The results refer to the ‘present’ period (1960–1999) a...
Conference Paper
We present here a set of regional climate simulations, complementary to the CORDEX-Africa modeling exercice, performed over West Africa during the 1989-2010 period using the non-hydrostatic model WRF. Lateral and SST forcings are provided by ERA-Interim reanalyses. The regional domain [45W 45E 10S 30N] encompasses West Africa and the nearby Atlanti...
Conference Paper
Full-text available
This study revisits the question of the Atlantic SSTs-Sahel rainfall teleconnection variability along the 20th century using gridded data sets (SST, rainfall), selected Sahel rainfall time-series (Dakar in Senegal; Nioro du Sahel and Mopti in Mali; Niamey, Maradi and Maine-Soroa in Niger) and climate indices (AMO and TSA). In this study, we introdu...
Article
Based on the approach of Fontaine et al. (2011) we study the accuracy of the African Monsoon (AM) simulations and expected future changes. We used 8 available CMIP5/AR5 AOGCMs from 8 different climate centres and the RCP4.5 emission scenario. Data are analysed with a multi-model approach and the "one model one vote" concept. The results refer to th...
Article
Full-text available
Le cycle de l'eau aux latitudes tropicales dépend en grande partie des états de surface de la Terre via la convection profonde. À ce titre, les Températures de surface marine (TSM) sont déterminantes. Leur étude montre une évolution à long terme significative : réchauffement sur le Pacifique depuis le milieu des années soixante-dix, compatible avec...
Article
This paper analyzes the atmospheric and rainfall anomaly patterns in the African-Indian monsoon region concomitant of warm/cold anomalies confined in the Mediterranean Sea in northern summer. It examines first the similarities and contrasts observed in longitudes, then discusses the results obtained regarding the normal in terms of climate impacts...
Article
Full-text available
Weather regimes (WRs) have been defined over the Euro-Mediterranean region (15°–70°N, 60°W–60°E) from May to October using the daily sea level pressure, 700-hPa geopotential height, and specific humidity from the European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA)-Interim over the 1989–2008 period. Computations are based on a neura...
Article
Full-text available
The West African Monsoon (WAM) influence on the interannual variability of the summer atmospheric circulation over North Atlantic and Europe is investigated over the period 1971-2000. A set of sensitivity experiments performed through the Arpege-Climat atmospheric general circulation model is analyzed, using the so-called "grid-point nudging" techn...
Article
Full-text available
The spatial coherence of boreal monsoon onset (July-September) over the western and central Sahel is studied through the analysis of daily rainfall records for 136 rain-gauges from 1950-2000. Onset of the rainy season has been defined using 3 definitions which rely on 3 overlapped spatial scales: (i) the regional scale, i.e. the northward ITCZ jump...
Article
This article focuses on some recent changes observed in the Tropics with special emphasis on the African monsoon region using high-resolution gridded precipitation from the Climatic Research Unit (period 1979-2002), outgoing longwave radiation at the top of the atmosphere from the National Oceanic and Atmospheric Administration and atmospheric rean...
Article
Full-text available
The Weather Regional Forecast (WRF) model is used in this study to downscale low-resolution data over West Africa. First, the performance of the regional model is estimated through contemporary period experiments (1981–1990) forced by ARPEGE-CLIMAT GCM output (ARPEGE) and ERA-40 re-analyses. Key features of the West African monsoon circulation are...
Article
Full-text available
Using sea surface temperature (SST), precipitation, and atmospheric information, this statistical study revisits the questions of the July–September SST-Sahel teleconnection variability after removing impact of quasi-global SSTs over the period 1900–2008. The eastern Mediterranean and the Indian Ocean dominate the relationship, both in terms of int...
Article
This study documents simulated precipitation and circulation changes through the 20C3M and A1b scenarios. It portrays a robust pattern, associating rainfall deficits in subtropical regions with rainfall excesses over West Africa, except in Northern Senegal and Mauritania, with a significant enhancement of both the April–June rainy season in 10/12 m...
Article
We review the studies carried out during the African Monsoon Multidisciplinary Analysis (AMMA)-EU on the changes of interannual sea surface temperature (SST)–West African monsoon (WAM) covariability at multidecadal timescales, together with the influence of global warming (GW). The results obtained in the AMMA-EU suggest the importance of the backg...
Article
Full-text available
The intraseasonal time scale is critical in West Africa where resources are highly rainfall dependent. Three main modes of variability have been identified, two with a mean periodicity of 15 days and one with a mean periodicity around 40 days. These modes have a regional scale and can strongly influence precipitation and convective activity. They a...
Article
Full-text available
Using SST, precipitation and atmospheric information, this statistical study revisits the questions of the July-September SST-Sahel teleconnection variability after removing impact of quasi-global SSTs over the period 1900-2008. The eastern Mediterranean and the Indian Ocean dominate the relationship, both in terms of intensity and time stability,...
Article
We review the studies carried out during the African Monsoon Multidisciplinary Analysis (AMMA)-EU on the changes of interannual sea surface temperature (SST)-West African monsoon (WAM) covariability at multidecadal timescales, together with the influence of global warming (GW). The results obtained in the AMMA-EU suggest the importance of the backg...
Article
The intraseasonal time scale is critical in West Africa where resources are highly rainfall dependent. Three main modes of variability have been identified, two with a mean periodicity of 15 days and one with a mean periodicity around 40 days. These modes have a regional scale and can strongly influence precipitation and convective activity. They a...
Article
Full-text available
La coherence spatiale du demarrage des pluies de mousson (juillet-septembre) au Sahel occidental et central a ete analysee a partir d’un reseau de 136 stations de 1950 a 2000. La date de demarrage de la saison des pluies a ete apprehendee selon trois echelles imbriquees : (i) l’echelle regionale du «saut de mousson », c’est-a-dire la migration brus...
Article
The spatial coherence of boreal monsoon onset (July-September) over the western and central Sahel is studied through the analysis of daily rainfall records for 136 rain-gauges from 1950-2000. Onset of the rainy season has been defined using 3 definitions which rely on 3 overlapping spatial scales: (i) the regional scale, i.e. the northward LTCZ jum...
Article
Weather Regimes (WR) have been defined over the Euro-Mediterranean region [60W-60E; 15N-70N] from May to October season using the daily Sea Level Pressure, 700 hPa geopotential height and specific humidity from ERA-interim dataset over the period 1989-2008. Computations are based on a neural network classification technique referred to as Self Orga...
Article
Full-text available
The influence of May to October SST anomalies in the Mediterranean sea (MED) on the West African monsoon (WAM) is investigated, analysing the outputs of numerical sensitivity experiments performed with three atmospheric general circulation models (ARPEGE, ECHAM, UCLA model) in the framework of the AMMA-FP6 project. The precipitation and atmospheric...
Article
Full-text available
Rainfall and circulation changes accompanying the Indian monsoon onset are examined, focusing on the African continent and neighboring areas. The Indian Meteorological Department official monsoon onset dates over Kerala (MOK: on average on 1 June) are used. Composites are formed at a pentad (5 days) time scale to compare pre- and postonset conditio...
Article
Full-text available
The summer monsoon onset over southern Vietnam is determined through a new criterion based on both in situ daily rainfall at six selected stations provided by the Institute of Meteorology and Hydrology, Vietnam, and the zonal component of the wind at 1,000hPa from the National Center for Environmental Prediction/Department of Energy Reanalysis 2. O...
Article
Full-text available
Using both empirical and numerical ensemble approaches this study focuses on the Mediterranean/West African relationship in northern summer. Statistical analyses utilize skin temperature, sea surface temperature, in situ and satellite rainfall, outgoing longwave radiation (OLR) observations and reanalyzed data winds and specific humidity on isobari...
Article
Full-text available
Madden–Julian oscillations (MJOs) are extracted over the Indo-Pacific basin using a local mode analysis. The convective perturbations are then projected over a larger domain to evaluate their remote consequences over the West African monsoon (WAM) intraseasonal variability. Rather weak (4–6 W m−2) convective fluctuations occurring in phase with tho...
Article
The aim of this work is to analyse observations and modelling experiments in order to give evidences of a large-scale atmospheric response to summer Mediterranean SST anomalies. Such a relevant feature was formulated on the basis of a recent encouraging idealized study by L. Z. X. Li (2006) who showed, for the first time, that winter Mediterranean...
Article
Full-text available
Le projet international Amma, d'initiative française, a pour objectif d'améliorer la connaissance et la compréhension de la mousson d'Afrique de l'Ouest et de sa variabilité, de l'échelle journalière à l'échelle interannuelle. Le projet est motivé par la forte variabilité des précipitations associées à ce système de mousson, et par ses conséquences...
Article
Full-text available
The monsoon onset is documented in terms of latitudinal shift of deep convection areas within the ITCZ using an interpolated version of the National Oceanic and Atmospheric Administration (NOAA) Outgoing Longwave Radiation (OLR) at a 5-day time-step over West Africa for the period 1979-2004. Signals in moist convection derived from OLR values lower...
Article
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This work assesses and compares the skill of direct and model-output-statistics (MOS) calibrated hindcasts of the July–August rainfall amounts for the dry period 1980–2000 over the Sahel issued from the Development of a European Multimodel Ensemble System for Seasonal to Interannual Prediction (DEMETER) experiment, with the aim to highlight among t...
Article
Full-text available
Annual cycle and inter-seasonal persistence of surface-atmosphere water and heat fluxes are analyzed at a 5-day time step over the West African Monsoon (WAM) through observational precipitation estimates (CMAP), model datasets (NCEP/DOE level 2 reanalyses) and a Soil Water Index (SWI) from the ERS scatterometer. Coherent fluctuations (30–90 days) d...
Article
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En Afrique de l'Ouest, les épidémies de méningite touchent chaque année entre 25 et 250 mille personnes (dont 10% de cas mortels) dans la zone latitudinale 10-15°N, dite « ceinture des méningites ». Bien que les facteurs sociaux prédisposent les populations aux épidémies, les conditions climatiques et environnementales semblent jouer un rôle import...