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匹配条件： “Yves K. Kouadio” ，找到相关结果约182258条。
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Estimates and Variability of the Air-Sea CO₂ Fluxes in the Gulf of Guinea during the 2005-2007 Period [PDF]
Urbain Koffi, Georges Kouadio, Yves K. Kouadio
Open Journal of Marine Science (OJMS) , 2016, DOI: 10.4236/ojms.2016.61002

Abstract: Measurements of CO₂ parameters (i.e. Total Alkalinity (TA) and Dissolved Inorganic Carbon (DIC)) were made from June 2005 to September 2007 in six EGEE (“Etude de la circulation océanique et de savariabilitédans le Golfe de GuinEE”) cruises to better assess air-sea CO₂ fluxes in the Gulf of Guinea (6°N - 10°S, 10°E - 10°W). Two empirical relationships TA-Salinity and DIC-Salinity-Temperature were established. These relationships were then used to estimate the monthly fugacity of CO₂ (fCO₂) and air-sea CO₂ fluxes. The monthly mean flux of CO₂ reaches 1.76 ± 0.82 mmol·m^-2·d^-1

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Analysis and Forecasting of the Impact of Climatic Parameters on the Yield of Rain-Fed Rice Cultivation in the Office Riz Mopti in Mali [PDF]
Angora Aman, Moussa Nafogou, Hermann Vami N’Guessan Bi, Yves K. Kouadio, Hélène Boyossoro Kouadio
Atmospheric and Climate Sciences (ACS) , 2019, DOI: 10.4236/acs.2019.93032

Abstract: During the period spanning the 1970s and1980s, countries in the West African Sahel experienced severe drought. Its impact on agriculture and ecosystems has highlighted the importance of monitoring the Sahelian rainy season. In Sahelian countries such as Mali, rainfall is the major determinant of crop production. Unfortunately, rainfall is highly variable in time and space. Therefore, this study is conducted to analyze and forecast the impact of climatic parameters on the rain-fed rice yield cultivation in the Office Riz Mopti region. The data were collected from satellite imagery, archived meteorology data, yield and rice characteristics. The study employed Hanning filter to highlight interannual fluctuation, a test of Pettitt and the standardized precipitation index (SPI) to analyze the rainfall variability. Climate change scenarios under the RCP 8.5 scenario (HadGEM-2 ES) and agroclimatic (Cropwat) model are carried out to simulate the future climate and its impact on rice yields. The results of satellite image classifications of 1986 and 2016 show an increase of rice fields with a noticeable decrease of bare soil. The analysis of the SPI reveals that over the 30 years considered, 56.67% of the rainy seasons were dry (1986-2006) and 43.33% were wet (2007-2015). The modelling approach is applied over 1986-2006 and 2007-2015 periods—considered as typical dry and rainy years—and applied over the future, with forecasts of climate change scenarios in 2034. The results show a decrease in potential yield during dry and slightly wet years. The yields of rain-fed rice will be generally low between 2016 and 2027. Deficits are observed over the entire study area, in comparison with the potential yield. Thus, this situation could expose the population to food insecurity.

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Tropical Atlantic Hurricanes, Easterly Waves, and West African Mesoscale Convective Systems
Yves K. Kouadio,Luiz A. T. Machado,Jacques Servain
Advances in Meteorology , 2010, DOI: 10.1155/2010/284503

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Abstract: The relationship between tropical Atlantic hurricanes (Hs), atmospheric easterly waves (AEWs), and West African mesoscale convective systems (MCSs) is investigated. It points out atmospheric conditions over West Africa before hurricane formation. The analysis was performed for two periods, June–November in 2004 and 2005, during which 12 hurricanes (seven in 2004, five in 2005) were selected. Using the AEW signature in the 700？hPa vorticity, a backward trajectory was performed to the African coast, starting from the date and position of each hurricane, when and where it was catalogued as a tropical depression. At this step, using the Meteosat-7 satellite dataset, we selected all the MCSs around this time and region, and tracked them from their initiation until their dissipation. This procedure allowed us to relate each of the selected Hs with AEWs and a succession of MCSs that occurred a few times over West Africa before initiation of the hurricane. Finally, a dipole in sea surface temperature (SST) was observed with a positive SST anomaly within the region of H generation and a negative SST anomaly within the Gulf of Guinea. This SST anomaly dipole could contribute to enhance the continental convergence associated with the monsoon that impacts on the West African MCSs formation. 1. Introduction The tropical North Atlantic is a World Ocean basin where cyclonic activity is intense. It presents a substantial interannual and interdecadal variability [1], depending directly on atmospheric and oceanic conditions. The Atlantic hurricane (H) activity occurs between July and November, and major Hs form in the Main Development Region (MDR), defined as the tropical North Atlantic south of 21°N and the Caribbean Sea. This cyclonic activity mainly originates from the African atmospheric easterly waves (AEWs) that propagate from West Africa towards the tropical North Atlantic basin and the Caribbean Sea [2, 3]. These waves, which have a 3-to-4-day period [4], are responsible for about 60% of tropical storms and minor Hs, and 85% of Hs of strong intensity [5–7]. Several studies [5, 8, 9] have even suggested that some tropical cyclones occurring in the eastern Pacific develop in association with AEWs that were initially generated in Africa and then propagated across the tropical Atlantic and Central America. Upstream in their propagation across the ocean, these AEWs are themselves generally accompanied by mesoscale convective systems (MCSs), which cross the center Sahel region between 8°N–18°N and 10°W–17°E and dissipate in the tropical Atlantic Ocean towards 20°W

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Numerical Study of a West African Squall Line Using a Regional Climate Model [PDF]
Benjamin Kouassi, Adama Diawara, Yves K. Kouadio, Guy Schayes, Fidèle Yoroba, Anderson A. Kouassi, Eric-Pascal Zahiri, Paul Assamoi
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.21003

Abstract: The squall line of 21-22 August 1992, documented during the HAPEX-Sahel campaign, is simulated using the regional atmospheric model (MAR). The simulated results are compared to observational data. The aim of this work is both to test the capacity of this model to reproduce tropical disturbances in West Africa and to use this model as a meteorological one. It allows simulating high moisture content in the lower layers. The MAR simulates well updrafts whereas downward currents are neglected. This result may be due to convective scheme used to parameterize the convection in the model. The forecast of stability indexes used to define violent storms shows that the model is able to reproduce the squall line. Despite some differences with the observational data, the model shows its ability to reproduce major characteristics of the mesoscale convective disturbances.

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Development of an Integrated Coastal Vulnerability Index for the Ivorian Coast in West Africa [PDF]
René A. Tano, Angora Aman, Elisée Toualy, Yves K. Kouadio, Bouo Bella Djézia Fran？ois-Xavier, Kwasi Appeaning Addo
Journal of Environmental Protection (JEP) , 2018, DOI: 10.4236/jep.2018.911073

Abstract: This study assesses the vulnerable state of the 566-km Ivorian coastal area using the physical (geomorphology, coastal slope, coastal retreat rate, relative sea level rise and wave/Tide energy) and socio-economic (coastal population density, harbor, airport, road, land use and protected area) factors as indicators. This enabled an Integrated Coastal Vulnerability Index to be determined for the Ivorian coastal zone. This Index could be defined as the weighted average of indexes based on physical and socio-economic factors. The study revealed that vulnerability of the western and the eastern coastlines of Cote d’Ivoire are strongly influenced by human activities, while physical forcing affects significantly the vulnerability of the central section. The relative vulnerability of the different sections depends also strongly on the geomorphology, wave energy, coastal population density and land use factors. The west and central sections of the coastline are more resilient than the eastern section when integrating physical and socio-economic factors. The Integrated Coastal Vulnerability Index, based on physical and socio-economic factors, appears to be more appropriate for coastal vulnerability assessment. These results could be useful in the development of adaptation strategies to increase the resilience of this coastal area and then extended for West Africa Coastal Areas Management.

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Characterization of the Boreal Summer Upwelling at the Northern Coast of the Gulf of Guinea Based on the PROPAO In Situ Measurements Network and Satellite Data
Yves K. Kouadio,Sandrine Djakouré,Angora Aman,K. Eugène Ali,Vamara Koné,Elisée Toualy
International Journal of Oceanography , 2013, DOI: 10.1155/2013/816561

Abstract: The boreal summer upwelling along the northern coast of the Gulf of Guinea (GG) is characterized using new in situ sea surface temperature (SST) from onset sensor and satellite TRMM Microwave Imager (TMI) datasets. This study aims to encourage intensive in situ SST measurements at the northern coast of the Gulf of Guinea. It shows good agreement between daily in situ SST and TMI SST and similar coastal upwelling onset date, end date, and durations calculated using both datasets. Interannual evolution of the onset date at four stations along the northern coast of GG indicates that the upwelling can be initiated at one cape or simultaneously at both the cape of palms and the cape of three points. It can be also initiated eastward towards Cotonou or globally off all the northern coasts of GG. Nonsignificant trend is found on upwelling onset date and end date variability. Moreover, this study shows that SST is significantly warm or cold some years. Ocean conditions during these years are related to known physical processes. 1. Introduction Coastal upwellings are characterized by seasonally low sea surface temperature (SST). They generally result from the response of the coastal ocean to alongshore winds, leading to the production of a relatively intense current with a small offshore and a large alongshore component [1]. This causes the pumping of cooler and nutrient-rich waters from the subsurface to the ocean surface. Upwelling areas are economically important even though the global area constituted by these regions is less than 1% of the global ocean [2]. Moreover, coastal upwellings have a great impact on local climate. Particularly, the coastal ocean surface conditions in the Gulf of Guinea situated in the northeastern equatorial Atlantic influence the West African climate [3]. Understanding the ocean dynamic of this region is then of great interest, (i) firstly because the Gulf of Guinea is the principal source of the water vapour which constitutes most of the precipitation on the continent. For example, Gu and Adler [4] linked the rainfall peak in May along the coastal area of the Gulf of Guinea to the seasonal forcing of the ocean. Eltahir and Gong [5] observed that the intensity of the West African monsoon depends on the meridional gradient of the static humid energy in the boundary layer between the ocean and the continent. (ii) Secondly, this tropical Atlantic area has the largest SST seasonal amplitude of about 5–8°C [6]. A coastal upwelling is observed each year along the northern coast of the Gulf of Guinea during the boreal winter and summer

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Heavy Rainfall Episodes in the Eastern Northeast Brazil Linked to Large-Scale Ocean-Atmosphere Conditions in the Tropical Atlantic
Yves K. Kouadio,Jacques Servain,Luiz A. T. Machado,Carlos A. D. Lentini
Advances in Meteorology , 2012, DOI: 10.1155/2012/369567

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Abstract: Relationships between simultaneous occurrences of distinctive atmospheric easterly wave (EW) signatures that cross the south-equatorial Atlantic, intense mesoscale convective systems (lifespan > 2 hour) that propagate westward over the western south-equatorial Atlantic, and subsequent strong rainfall episodes (anomaly > 10？mm·day？1) that occur in eastern Northeast Brazil (ENEB) are investigated. Using a simple diagnostic analysis, twelve cases with EW lifespan ranging between 3 and 8 days and a mean velocity of 8？m·s？1 were selected and documented during each rainy season of 2004, 2005, and 2006. These cases, which represent 50% of the total number of strong rainfall episodes and 60% of the rainfall amount over the ENEB, were concomitant with an acceleration of the trade winds over the south-equatorial Atlantic, an excess of moisture transported westward from Africa to America, and a strengthening of the convective activity in the oceanic region close to Brazil. Most of these episodes occurred during positive sea surface temperature anomaly patterns over the entire south-equatorial Atlantic and low-frequency warm conditions within the oceanic mixing layer. A real-time monitoring and the simulation of this ocean-atmosphere relationship could help in forecasting such dramatic rainfall events. 1. Introduction The Northeast region of Brazil (NEB) is located between the parallels 01°S and 18°S and the meridians 35°？W and 47°W (Figure 1(a)). The climatic regime is semiarid for more than 80% of the area and the region often experiences dramatic droughts [1] and catastrophic floods (i.e., in May-June 2010 (http://www.lepoint.fr/monde/bresil-plus-de-1-000-disparus-dans-les-inondations-dans-le-nord-est-22-06-2010-469027_24.php.)). The majority of the population lives along the coast, where the rainfall regime is mainly under the influence of the tropical oceanic climate [2–7]. The regular rainy season occurs from January to June in the eastern part of NEB localized between 2.5°S–12.5°S; 40°W–35°W (Figure 1(a)), with possible extensions of a few weeks before or after this period due to substantial interannual variability and distinctive subregional climate regimes. Differences in the length or intensity of the rainy season are due by several ocean-atmospheric processes or a combination of them. Figure 1: (a) Spatial distribution of 682 rain gauges over ENEB. (b) 2004–2006 GPCP and in situ monthly rainfall (mm·day ？1) averaged over ENEB. Seasonal latitudinal migration across the equator of a zonal band of rainfall which is linked to the Inter-Tropical Convergence

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Estimation of the Carbon Sequestration Dynamics of Senegal’s Great Green Wall Based on Land Cover over the Past Three Decades [PDF]
Bi Tra Olivier Gore, Angora Aman, Yves K. Kouadio, Ody-Marc Duclos, Kazunao Sato
Journal of Environmental Protection (JEP) , 2023, DOI: 10.4236/jep.2023.1412053

Abstract: The severe drought observed in the Sahel during 1970s, 1980s and 1990s has deeply affected the population as well as the economies and the eco-systems of this climatic area. The GGW Initiative spearheaded by Africa Union in 2007 proposed to combat the land degradation and desertification by planting a wall of trees stretching from Dakar to Djibouti. A reforestation was then conducted in the Senegal’s GGW since 2006 as part as other areas in the Sahel. This paper aims to evaluate the carbon sequestration dynamics in the sites of the Senegal’s GGW over the last three decades. The method consists firstly of analyzing the evolution of land cover and land use dynamics based on ESA-CCI LC satellite data. There is an improvement of the surface areas of tree and shrub savanna of 11.40% (Tessekere), 8.25% (Syer) and 2.70% (Loughere-Thioly). The regreening of the different localities and a positive dynamic observed is explained by the return to normal rainfall and to reforestation actions, agroforestry practices, better management of natural resources undertaken. However, some non-reforested sites showed an opposite trend despite of the normal rainfall. Secondly, the results on land mapping are used as a proxy for the assessment of carbon stocks. The dynamic observed in vegetation cover since the beginning of the reforestation made it possible to sequester 5.8 million tons of carbon representing respectively 2.31% of African GGW. This gain in stored carbon is equivalent to 21.2 million tons of CO₂ captured in the atmosphere. Through this study, it appears that carbon storage becomes significant 8 to 10 years after the start of reforestation. An urbanization without respect for the environmental factors could be a danger for the climate (case of Ballou).

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