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Influence of Continental Atmospheric Forcing on the decadal Variability of the West African Monsoon

Atmospheric and climate Sciences 2024年第1期14卷 1-28页

作者： Adjoua Moïse Landry Famien Sandrine djakouré Bi Tra Jean Claude Youan Serge Janicot Abé delfin ochou Arona diedhiou département des Sciences et Techniques Université Alassane Ouattara de Bouaké Bouaké C&#244te d’Ivoire LASMES-UFR SSMT Université Félix Houphou&#235t Boigny d’Abidjan Abidjan C&#244te d’Ivoire LSS-UFR SSMT Université Félix Houphou&#235t Boigny d’Abidjan Abidjan C&#244te d’Ivoire laboratoire d’océanographie et du climat: expérimentations et approches numériques Sorbonne Université IRD CNRS MNHN Paris France Université Grenoble Alpes IRD CNRS Grenoble INP IGE Grenoble France UFHB-IRd Joint International Laboratory of Research on NEXUS climate Water Energy and Agriculture and Development of Cli-mate Services African Centre of Excellence CCBAD (Climate Change Biodiversity and Sustainable Agriculture) Université Félix Houphou&#235t-Boigny Abidjan C&#244te D’Ivoire

The West African Monsoon (WAM) is characterized by strong decadal and multi-decadal variability and the impacts can be catastrophic for the local populations. One of the factors put forward to explain this variability involves the role of atmospheric dynamics, linked in particular to the Saharan Heat Low (SHL). This article addresses this question by comparing the sets of preindustrial control and historical simulation data from climate models carried out in the framework of the CMIP5 project and observations data over the 20th century. Through multivariate statistical analyses, it was established that decadal modes of ocean variability and decadal variability of Saharan atmospheric dynamics significantly influence decadal variability of monsoon precipitation. These results also suggest the existence of external anthropogenic forcing, which is superimposed on the decadal natural variability inducing an intensification of the signal in the historical simulations compared to preindustrial control simulations. We have also shown that decadal rainfall variability in the Sahel, once the influence of oceanic modes has been eliminated, appears to be driven mainly by the activity of the Arabian Heat Low (AHL) in the central Sahel, and by the structure of the meridional temperature gradient over the inter-tropical Atlantic in the western Sahel.

关键词： Influence of Continental Atmospheric Forcing on the decadal Variability of the West African Monsoon

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Cropping leads to loss of soil organic matter: How can we prevent it?

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Pedosphere 2023年第1期33卷 8-10页

作者： Vincent CHAPLOT Pete SMITH Institut de Recherche pour le développement(IRd) Laboratoire d’Océanographie et du ClimatExpérimentations et Approches NumériquesUMR 7159IRD-CNRS-UPMC-MNHNCedex 05Paris 75252France Institute of Biological and Environmental Sciences School of Biological SciencesUniversity of AberdeenAberdeen AB243UUUK

Soil organic matter(SOM),which associates carbon(C)to key plant nutrients,has been stored in soil for thousands of *** have long recognised its positive impact on key environmental functions such as food production and climate *** soon as a virgin land(forest or grassland)is cultivated,there is a tendency for the soil to lose its SOM,and we still largely misunderstand the underlying mechanisms,leading to inappropriate decisions being taken to fight soil,climate,and overall ecosystem degradation.

关键词： soil grassland forest

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PROFHMM_UNC: Introducing a Priori Knowledge for Completing Missing Values of Multidimensional Time-Series

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International Journal of Communications, Network and System Sciences 2014年第8期7卷 316-329页

作者： A. A. Charantonis F. Badran S. Thiria laboratoire CEdRIC Conservatoire National des Arts et Métiers Paris France laboratoire d’océanographie et du climat: expérimentation et approches numériques Université Pierre et Marie Curie Paris France

We present a new method for estimating missing values or correcting unreliable observed values of time dependent physical fields. This method, is based on Hidden Markov Models and Self-Organizing Maps, and is named PROFHMM_UNC. PROFHMM_UNC combines the knowledge of the physical process under study provided by an already known dynamic model and the truncated time series of observations of the phenomenon. In order to generate the states of the Hidden Markov Model, Self-Organizing Maps are used to discretize the available data. We make a modification to the Viterbi algorithm that forces the algorithm to take into account a priori information on the quality of the observed data when selecting the optimum reconstruction. The validity of PROFHMM_UNC was endorsed by performing a twin experiment with the outputs of the ocean biogeochemical NEMO-PISCES model.

关键词： Multidimensional Time-Series Completion Hidden Markov Models Self-Organizing Maps

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Nutrient Input and CO<sub>2</sub>Flux of a Tropical Coastal Fluvial System with High Population density in the Northeast Region of Brazil

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Journal of Water Resource and Protection 2013年第3期5卷 362-375页

作者： Moacyr Araujo Carlos Noriega dóris Veleda Nathalie Lefèvre departamento de oceanografia Centro de Estudos e Ensaios em Riscos e Modelagem Ambiental Universidade Federal de Pernambuco Recife Brazil laboratoire d’océanographie et du climat: expérimentation et approches numériques Université Pierre et Marie Curie. 4 Paris France

The carbon dioxide flux through the air-water interface of coastal freshwater ecosystems must be quantified to understand the regional balances of carbon and its transport through coastal and estuarine regions. The variations in air-sea CO2 fluxes in nearshore ecosystems can be caused by the variable influence of rivers. In the present study, the amount of carbon emitted from a tropical coastal river was estimated using climatological and biogeochemical measurements (2002-2010) obtained from the basin of the Capibaribe River, which is located in the most populous and industrialized area of the northeast region of Brazil. The results showed a mean CO2 flux of +225 mmol·m-2·d-1, mainly from organic material from the untreated domestic and industrial wastewaters that are released into the river. This organic material increased the dissolved CO2 concentration in the river waters, leading to a partial pressure of CO2 inthe aquatic environment that reached 31,000 μatm. The months of April, February and december (the dry period) showed the largest monthly means for the variables associated with the carbonate system (, dIC, CO2(aq), CO32-, TA, temperature and pH). This status reflects the state of permanent pollution in the basin of the Capibaribe River, due, in particular, to the discharge of untreated domestic wastewater, which results in the continuous mineralization of organic material. This mineralization significantly increases the dissolved CO2 content in the estuarine and coastal waters, which is later released to the atmosphere.

关键词： Tropical River Nutrient Load CO2 Flux Anthropogenic Pollution Freshwater Ecosystem Impact

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climate Services Elaboration for Cocoa Cultivation in Côte d’Ivoire: Contribution of CORdEX climate Projections

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Agricultural Sciences 2024年第3期15卷 358-375页

作者： Adama Bamba Fidèle Yoroba N’datchoh Evelyne Toure Kouakou Kouadio Mory Ouattara Kakou M’bo Mamadou Cherif daouda Kone Arona diedhiou laboratoire des sciences de la Matière de l’Environnement et de l’Energie Solaire (LASMES) Université Félix Houphou&#235t Boigny Abidjan C&#244te d’Ivoire Centre d’Excellence Africain en Changement climatique Biodiversité et Agriculture Durable (CCBAD) Université Félix Houphou&#235t Boigny Abidjan C&#244te d’Ivoire laboratoire Mixte International Climat-Eau-Energy-Agriculture Université Félix Houphou&#235t Boigny Abidjan C&#244te d’Ivoire Station Géophysique de LAMTO N’Douci C&#244te d’Ivoire UFR Bioscience Université Félix Houphou&#235t Boigny Abidjan C&#244te d’Ivoire Université Grenoble Alpes IRD CNRS Grenoble-INP IGE Grenoble France

This study assessed the contribution of climate projections to improving rainfall information for cocoa crops in the central and southern regions of Côte d’Ivoire. Particular attention was paid to fourteen localities in these two climatic zones. Simulation data were obtained from the CORdEX ensemble and observation data from CHIRPS. They cover the period 1991-2005 for the reference period and the future period from 2021 to 2050 for the RCP4.5 and RCP8.5 scenarios. In addition, the study was based on the water requirements necessary during the critical phase of the cocoa tree (the flowering phase) for a good yield from the cocoa production chain on the one hand, and on a selection of three climate indices Cdd, CWd and r95PTOT to study their spatio-temporal changes over two future periods 2021-2035 (near future) and 2036-2050 (medium-term) on the other. These climatic indices influence cocoa cultivation and their use in studies of climatic impacts on agriculture is of prime importance. The analysis of their spatio-temporal changes in this work also contributes to providing climate services based on rainfall, to which cocoa crops are highly sensitive. Our results show that the Cdd and CWd indices vary from one region to another depending on latitude. For the fourteen localities studied, the number of consecutive dry days (Cdd) could increase between now and 2050, while the number of consecutive wet days (CWd) could decrease over the period 2021-2035 and then increase over the period 2036-2050. The localities of Tabou, Aboisso and San-Pedro record high numbers of Cdd index and CWd index for both projection scenarios. In comparison with the RCP4.5 and RCP8.5 scenarios, these results show that the RCP8.5 scenarios are having an impact on cocoa growing in Côte d’Ivoire.

关键词： Cocoa RCP4.5 RCP8.5 climate Indices Côte d’ivoire

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Towards an enhanced interpretation of δ18O changes during the past 300 kyr over Asia

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National Science Review 2022年第11期9卷 63-64页

作者： Gilles Ramstein laboratoire des Sciences du climat et de l’Environnement LSCE/IPSL CEA-CNRS-UVSQUniversite Paris-Saclay

For many decades, the impact of orbital forcing on monsoon systems has been intensively studied. Rapidly, attention has been drawn to the Mid-Holocene due to the ’Green Sahara’, which was depicted, using many different proxies, as much more humid than the present-day desert. It also corresponds to enhanced Asian monsoons [1]. climate models have been used to simulate this period.

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Seasonal compensation implied no weakening of the land carbon sink in the Northern Hemisphere under the 2015/2016 El Niño

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Science China Earth Sciences 2024年第1期67卷 281-294页

作者： Fangzhong SHI Xiuchen WU Xiaoyan LI Philippe CIAIS Hongyan LIU Chao YUE Yuting YANG Shulei ZHANG Shushi PENG Yi YIN Benjamin POULTER deliang CHEN State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China Key Laboratory of Tibetan Plateau Land Surface Processes and Ecological Conservation Qinghai Normal UniversityXining 810016China Research and development Center for Watershed Environmental Eco-Engineering Beijing Normal University(Zhuhai)Zhuhai 519085China laboratoire des Sciences du climat et de l’Environnement(LSCE) CEA-CNRS-UVSQUMR821291191Gif-sur-YvetteFrance College of Urban and Environmental Science MOE Laboratory for Earth Surface ProcessesPeking UniversityBeijing 100871China State Key Laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing 100084China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) School of Atmospheric SciencesSun Yat-sen UniversityGuangzhou 510275China California Institute of Technology PasadenaCA 91125USA Biospheric Sciences Laboratory NASA Goddard Space Flight CenterGreenbeltMaryland 20771USA Regional climate Group Department of Earth SciencesUniversity of GothenburgGothenburg SE-40530Sweden

The recurrent extreme El Niño events are commonly linked to reduced vegetation growth and the land carbon sink over many but discrete regions of the Northern Hemisphere(NH).However,we reported here a pervasive and continuous vegetation greening and no weakened land carbon sink in the maturation phase of the 2015/2016 El Niño event over the NH(mainly in the extra-tropics),based on multiple evidences from remote sensing observations,global ecosystem model simulations and atmospheric CO_(2)*** discovered a significant compensation effect of the enhanced vegetation growth in spring on subsequent summer/autumn vegetation growth that sustained vegetation greening and led to a slight increase in the land carbon sink over the spring and summer of 2015(average increases of 23.34%and 0.63%in net ecosystem exchange from two independent datasets relative to a 5-years average before the El Niño event,respectively)and spring of 2016(6.82%),especially in the extra-tropics of the NH,where the water supply during the pre-growing-season(November of the previous year to March of the current year)had a positive *** seasonal compensation effect was much stronger than that in 1997 and 1998 and significantly alleviated the adverse impacts of the 2015/2016 El Niño event on vegetation growth during its maturation *** legacy effect of water supply during the pre-growing-season on subsequent vegetation growth lasted up to approximately six *** findings highlight the role of seasonal compensation effects on mediating the land carbon sink in response to episodic extreme El Niño events.

关键词： El Niño Seasonal compensation effect Vegetation greening Land carbon sink Net ecosystem exchange Legacy effect

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太平洋十年涛动对全球地表气温变化的影响足迹

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Science Bulletin 2024年第4期69卷 445-448页

作者：梁莉莉 Alan d.Ziegler 陈德亮 Philippe Ciais 李肇新梁时婧王大山徐荣嵘曾振中 School of Environmental Science and Engineering Southern University of Science and TechnologyShenzhen 518055China SUSTech Energy Institute for Carbon Neutrality Southern University of Science and TechnologyShenzhen 518055China Faculty of Fisheries Technology and Aquatic Resources Mae Jo UniversityChiang Mai 50000Thailand Regional climate Group Department of Earth SciencesUniversity of GothenburgGothenburg 40530Sweden laboratoire des Sciences du climat et de l’Environnement UniversitéParis-SaclayGif-sur-Yvette 91191France laboratoire de Météorologie dynamique Centre national de la recherche scientifiqueSorbonne UniversitéÉcole Normale SupérieureÉcole PolytechniqueParis 75000France Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control School of Environmental Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China

Sea surface temperature modes have been found to modulate anthropogenic global warming rates on annual and decadal timescales,sometimes leading to periods of“slowdown”despite increasing greenhouse gas emissions^([1]).

关键词：太平洋十年涛动地表气温 greenhouse

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Mapping global forest biomass and its changes over the first decade of the 21st century

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Science China Earth Sciences 2019年第3期62卷 585-594页

作者： Anping CHEN Shushi PENG Songlin FEI department of Forestry and Natural Resources Purdue University The Woods Hole Research Center laboratoire des Sciences du climat et de l'Environnement(LSCE) CEA-CNRS-UVSQ

Forests played an important role in carbon sequestration during the past two decades. Using a model tree ensemble method(MTE) to regress the seven reflectance bands of EOS-Terra-MOdIS satellite data against country level forest biomass carbon density(BCd) of 2001–2005 provided by United Nations' s Forest Resource Assessment(FRA), we developed a global map of forest BCd at 1 km×1 km resolution for both 2001–2005 and 2006–2010. For 2006–2010, the total global forest biomass carbon stock is estimated as 279.6±7.1 Pg C, and the tropical forest biomass carbon stock is estimated as 174.4±5.4 Pg C. during the first decade of the 21 st century, we estimated an increase of global forest biomass of 0.28±0.75 Pg C yr^(-1). Tropical forest biomass carbon stock slightly decreased(-0.31±0.60 Pg C yr^(-1)); by contrast, temperate and boreal forest biomass increased(0.58±0.28 Pg C yr^(-1)) during the same period. Our estimation of the global forest biomass carbon stock and its changes is subject to uncertainties due to lack of extensive ground measurements in the tropics, spatial heterogeneity in large countries, and different definitions of forest. The continuously monitoring of forest biomass carbon stock with MOdIS satellite data will provide useful information for detecting forest changes.

关键词： Forest biomass Carbon stock Model tree ensemble(MTE) MOdIS Remote sensing

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Spatial distribution of Cordex Regional climate Models Biases over West Africa

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International Journal of Geosciences 2015年第9期6卷 1018-1031页

作者： Alioune Badara Sarr Moctar Camara Ibrahima diba laboratoire d’océanographie des Sciences de l’Environnement et du Climat (LOSEC) Université Assane SECK de Ziguinchor Ziguinchor Senegal

The objective of this work is to analyze the spatial distribution of biases of nine (9) regional climate models (RCMs) and their ensemble average used under the framework of COordinated Regional climate downscaling experiment (CORdEX) project over West Africa during the summer period. We assessed the ability of RCMs to represent adequately West African summer rainfall by analyzing some statistical parameters such as the relative bias, the standard deviation, the root mean square error (RMSE) and the correlation coefficient between observation data (GPCP used as reference) and regional climate models outputs. We first analyzed the relative bias between GPCP climatology and the other available observed data (CRU, CMAP, UdEL, GPCC, TRMM and their ensemble mean). This analysis highlights the big uncertainty on the quality of these observed rainfall data over West Africa which may be largely due to the rarity of?in situ?measurement data over this region. The statistical analysis with respect to GPCP rainfall shows the presence of large relative bias values over most part of West Africa for engaged RCMs. However their ensemble mean outperforms individual RCMs by exhibiting the weakest relative change. The RMSE values are weak over West Africa except over and off the Guinea highlands for RCMs and the Era-interim reanalysis. The spatial distribution of the coefficient of correlation between the observation data and RCMs shows that all models (except HIRHAM) present positive values over the Northern Sahel and the Gulf of Guinea. The model of the dMI exhibits the weakest values of correlation coefficient. This study shows that RCMs simulate West African climate in a satisfactory way despite the fact that they exhibit systematic biases.

关键词： CORdEX Regional climate Models Rainfall

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