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Influence of Sea Level Pressure on Inter-Annual Rainfall Variability in Northern Senegal in the Context of Climate Change

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Atmospheric and Climate Sciences 2022年第1期12卷 113-131页

作者： Aichetou Dia-diop Malick Wade Sinclaire Zebaze Abdoulaye bouya diop Eric Efon Andre Lenouo bouya diop Laboratoire des Sciences de l’Atmosphère et des Océans—Matériaux-énergie-Dispositifs (LSAO-MED) Université Gaston Berger Saint-Louis Sénégal Department of Physics Faculty of Science University of Yaoundé 1 Yaoundé Cameroon Department of Physics Faculty of Science University of Bamenda Bamenda Cameroon

This study examines the inter-annual variability of rainfall and Mean Sea Level Pressure (MSLP) over west Africa based on analysis of the Global Precipitation Climatology Project (GPCP) and National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis respectively. An interconnection is found in this region, between Mean Sea Level Pressure (MSLP) anomaly (over Azores and St. Helena High) and monthly mean precipitation during summer (June to September: JJAS). We also found that over northern Senegal (15°N - 17°N;17°W - 13°W) the SLP to the north is strong;the wind converges at 200 hPa corresponding to the position of the African Easterly Jet (AEJ) the rotational wind 700 hPa (corresponding to the position of the African Easterly Jet (AEJ) coming fro

关键词： Global Precipitation Climatology Project (GPCP) West Africa monsoon Inter-Tropical Convergence Zone African Easterly Jet (AEJ) Tropical Easterly Jet (TEJ) Sea Level Pressure (SLP)

Spatial and Temporal Distribution of Rainfall Breaks in Senegal

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American Journal of Climate Change 2021年第4期10卷 533-560页

作者： Bara Ndiaye Mahamat Adoum Moussa Malick Wade Abdoulaye Sy Abdoulaye bouya diop Aichetou Dia diop bouya diop Aboubakary Diakhaby Laboratoire des Sciences de l’Atmosphère et de Océans Matériaux énergie Dispositifs (LSAOMED) Saint-Louis Senegal

This study analyzes the spatio-temporal distribution of daily rainfall data from 13 stations in the country of Senegal located in the North-West of Africa. These data, covering the period 1950-2010, are extracted from the database of the Regional Study Center for the Improvement of Drought Adaptation (CERAAS). They allow to calculate, in each station, dry episodes and their sequences and the results reveal a latitudinal variability of class 1 breaks (1 - 3 days) with the highest values recorded in the south. Unlike the class 2 episodes (greater or equal than 15 days), the latitudinal gradient is less pronounced but they are more frequent in the north. For most of the regions studied, a break in the trend towards an increase in dry sequences can be noted, most often at the beginning of the 1970s, which coincides with the start of the great drought of the 1970s decade. For all sites, the frequency of dry episodes of class 1 (1 - 3 days) exceeds 70%. The frequency of class 2 of dry episodes (greater or equal than 15 days) decreased from 30% in 1951-1970 to 18% in 1991-2010 in the region of Thiès;from 25% in 1951-1970 to 20% in 1991-2010 in Louga;from 22% in 1951-1970 to 18% in 1991-2010 in Tamba;23% in 1951-1970 to 15% in 1991-2010 in Ziguinchor;25% in 1951-1970 to 16% in 1991-2010 in Kolda;22% in 1951-1970 to 18% in 1991-2010 in Diourbel and finally 20% in 1951-1970 to 17% in 1991-2010 in Fatick. Over the whole period of study, the spatial distribution of the number of dry periods in class 1 is higher in the South than in the Center and in the North of Senegal. For class 2 breaks, the latitudinal gradient is less pronounced and the minimum number of dry periods in this class is recorded in the south, especially in Ziguinchor. However, the maximum is observed in the Center. In the Northern region (Saint-Louis), classes 3 and 4 are much more frequent. This spatial variability of rainfall breaks is clearly associated with the rainfall gradient between the North and the S

关键词： Rainfall Rainfall Breaks Great Drought Senegal Consecutive Dry Days

Comparative Analysis of Ranging Protocols for Localization by UWB in Outdoor

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Wireless Sensor Network 2018年第5期10卷 103-117页

作者： Salick Diagne Thierry Val Abdou Karim Farota bouya diop Laboratoire des Sciences de l’Atmosphère et des Océans UFR SAT/UGB Saint-Louis Sénégal Institut de Recherche en Informatique de Toulouse Université de Toulouse Blagnac France

The rapid evolution of technology in the field of wireless telecommunications and micro components using MEMS technologies (Micro-electromechanical systems) has contributed to the expansion and rapid development of wireless sensor networks (WSN). This rapid development has contributed to the appearance of sensor and actuator networks (WSAN) or even to the Internet of Things with DL-IoT (Device Layer-Internet of Things). This rapid evolution of WSN is due to the enthusiasm generated by this last in industry and research. This new technology is used in several applications, particularly in the outdoor location of communicating nodes. The process of distance calculation between nodes (ranging) is a primordial phase for a precise location of these nodes. This paper presents the result of measurements does with three ranging protocols (TWR, TWR_Skew and SDS-TWR) implemented on DecaWiNo nodes. DecaWiNo nodes use the Ultra-Wide Band (UWB) radio links, proposed by the IEEE 802.15.4 standard amendment of the year 2007, which provides a high-performance ranging by ToF (Time of Flight) [1] [2]. The results are very promising with precision errors of the order of 50 cm over 20 meters.

关键词： Outdoor Location UWB Ranging ToF TWR DecaWiNo

Trend and Return Level Analysis of Extreme Rainfalls in Senegal

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Journal of Water Resource and Protection 2022年第3期14卷 221-237页

作者： Mamadou Sarr Mahamat Adoum Moussa El Hadji Deme bouya diop Laboratoire des Sciences de l’Atmosphère et des Océans Matériaux-Energies-Dispositifs (LSAOMED) Université Gaston Berger Saint-Louis Sénégal Ecole Nationale Supérieur des TIC (ENASTIC) N’Djamena Tchad Laboratoire d’Etudes et de Recherches en Statistique et Développement (LERSTAD) Université Gaston Berger Saint-Louis Sénégal

In recent years, Senegal has been confronted with increasingly frequent and damaging extreme events. In the context of climate change, we conducted this study to characterize the trends of rainfall extremes in Senegal. In this work, we used daily rainfall data from 27 stations in Senegal from the period 1951 to 2005 (55 years). To study their linear trends, non-stationary extreme value models with time as a covariate are fitted to evaluate them. Our results indicate a decreasing trend of extreme rainfalls at most of the stations except for 5 stations. However, the decreasing trends are only significant for two stations (Thiès and Kidira), however, this can only be taken as information that climate change may have already impacted extreme rainfalls. For the 20-year and 30-year return periods, the results show that they have undergone changes, in fact for almost all stations, the trends in return periods are decreasing.

关键词： Climate Change Extreme Rainfall Rain Trend Return Level Senegal

Characterization of Spatio-Temporal Variability of Irradiation, Nebulosity and Aerosols Optical Depth in 10˚North-20˚North African Band

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American Journal of Climate Change 2022年第2期11卷 155-171页

作者： Abdoulaye bouya diop Abdoulaye Sy Malick Wade Abdoul Karim Mbodj Abdou Karim Farota Adoum Mahamat Moussa Babacar Niang Aicha Dia diop Bara Ndiaye bouya diop Amadou Thierno Gaye Aboubakary Diakhaby LSAO-MED Gaston Berger University Saint Louis Senegal CERDI Clermont Auvergne University Clermont Auvergne France University of Tchad Djamena Tchad LPAOSF ESP Cheikh Anta diop Univesity Dakar Senegal

This work concerns the 10? North, 20? North African band. Area renowned for having some of the poorest countries in the world. It is also home to the Sahelian strip and part of the Sahara. The countries in this zone have a relatively low electrification rate compared to the enlightened country. To solve this problem, these countries want to turn to renewable energies such as photovoltaics (renewable energy obtained through solar radiation). Therefore, understanding the behavior of irradiation and cloudiness in the 10 - 20 band becomes necessary. The application of the empirical orthogonal functions to the different cloud layers and to the irradiation reveals a seasonality of the latter, in particular compared to the first modes of the empirical orthogonal functions (EOF1). Indeed, by filtering in time and space to isolate solar radiation and cloudiness, the EOF1 expresses respectively 94.3% of the variation of descending solar radiation in clear sky in the 10 - 20 band. Note 65.7% for global radiation, 54.4% for cloudiness at 450 hPa, 69.6% for cloudiness between 800 hPa and 450 hPa, 76.6% for low cloudiness, 61.4% for total cloudiness. These results allow us to say that we have generally good sunshine over several months, with little cloud cover in this band. However, since this zone is considered to be part of the main aerosol emission source zones, it is important in their temporal consideration of the optical depth. By doing the wavelet analysis on the optical depth data from Dakar and Banizoumbou, we note that the average dust presence spectrum over the entire period from 1997 to 2019 in the two stations with a slight shift compared to the peaks and the maximum observed value. A sign that there is a strong presence of dust in this area and that it should be taken into account for any photovoltaic installation in this area.

关键词： Sahel Irradiation Cloudiness Aerosol EOF Wavelet

Study of the Spatio-Temporal Variability of Rainfall in the Northern Region of Senegal

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Journal of Geoscience and Environment Protection 2023年第4期11卷 1-14页

作者： Aichétou Dia diop Abdoul Karim Mbodji El Hadji Deme Malick Wade Mahamat Adoum Moussa Abdoulaye bouya diop Younousse Biaye Djiby Sarr Abdou Karim Farota Aboubakary Diakhaby bouya diop Laboratoire des Sciences de l’Atmosphère et des Océans Matériaux Energies Dispositifs UGB Saint Louis Senegal Laboratoire D’études et de Recherches en Statistiques et Développement University Gaston Berger (UGB) Saint Louis Senegal Ecole Nationale Supérieure des TIC N’Djamena Tchad

Senegal is a country of the Sahel. In this region, most of the populations live from agro-pastoral activities. The northern zone of Senegal is strongly influenced by river cultures. And the dynamics of the Senegal River are dependent on rainfall. The rainfall in the area is very closely linked to the dynamics of the atmosphere. The study of the spatio-temporal variability of rainfall in the northern region of Senegal requires quality rainfall observation data. It includes the Ferlo and the Senegal River valley, in particular the regions of Louga (department of Linguère included), Saint-Louis (departments of Dagana and Podor included) and Matam. These stations have been defined since Le Borgne (1988). The difficulty of having quality rain observation data can be resolved by using more accessible and good quality satellite data. Using satellite data, namely MSWEP, CRU, TAMSAT, ARC and PERSIANN, we showed the return of precipitation that appeared in 2000 and the unimodal cycle of precipitation in our study area. These data were validated using the correlation coefficient, the bias, the RMSE and the Nash index with observation data from the Regional Study Center for the Improvement of Adaptation to Drought (CERASS). The CRU data is then retained. Thus, this study made it possible to show the zonal distribution of rainfall in the northern zone of Senegal.

关键词： Rainfall in the Northern Region of Senegal Variability of Rainfall Satellite Data The Zonal Distribution of Rainfall

Solar Energy Recovery and Storage System for Powering Wireless Communicating Nodes

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Energy and Power Engineering 2021年第12期13卷 377-391页

作者： Salick Diagne Abdou Karim Farota Ognadon Assogba bouya diop Thierry Val Gaston Berger University Saint-Louis Senegal IRIT University of Toulouse 2 Toulouse France

We find nowadays in several fields of application the presence of IoT technology such as wireless sensor and actuator networks. In this technology, one of the main points of study is the management of energy consumption. In this article, we provide a solar energy harvesting and storage system for powering wireless nodes. The system we propose uses a low power solar pane a P & O control adapted to fuzzy logic for the MPPT. For energy storage, we used the supercapacitor technology. The simulation of the models shows better results than using the P & O command for an autonomous power supply of the wireless communicating nodes in the study region.

关键词： Solar Energy Energy Recovery Supercapacitor Fuzzy Logic

Performances Analysis of a System of Localization by Angle of Arrival UWB Radio

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International Journal of Communications, Network and System Sciences 2020年第2期13卷 15-27页

作者： Salick Diagne Thierry Val Abdou Karim Farota bouya diop Ognadon Assogba Laboratoire des Sciences de l’Atmosphère et des Océans: Matériaux Energies et Dispositifs (LSAO-MED) Gaston Berger University Saint-Louis Senegal IRIT University of Toulouse2 Toulouse France

The increasingly widespread use of sensor and actuator networks and in general of the Internet of Things (IoT) in several areas of precision, imposes upon localization systems that can often equip them with a robust and more precise localization. It is in this sense that UWB technology has proved to be one of the most powerful communication technologies for these localization systems;thanks, in particular to the bandwidth occupied instantaneously by the signal allowing a very fine temporal resolution. Constructors have set up localization kits based on various technologies. These kits facilitate in a way the work of localization of users. In this paper, we present results on the performance study of the Decawave PDoA Kit. This Kit uses the PDoA (Phase Difference of Arrival) to determine the Angle of Arrival (AoA) parameter with UWB technology. This study is in context of localization by AoA for an application to protect agricultural crops against grain-eating birds. The results of the study show overall AoA measurement errors around 10 degrees in an ideal environment.

关键词： Angle of Arrival (AoA) Localization UWB PDoA

Interannual Variability of Rainfall over the West Africa Sahel

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Journal of Geoscience and Environment Protection 2020年第3期8卷 85-101页

作者： Aichetou Dia-diop Sinclaire Zebaze Malick Wade Rinelle Ngongang Djiondo bouya diop Eric Efon Andre Lenouo Laboratoire des Sciences de l’Atmosphère et des Océans-Matériaux-énergie-Dispositifs (LSAO-MED) Université Gaston Berger Saint-Louis Sénégal Department of Physics Faculty of Science University of Douala Douala Cameroon Department of Physics Faculty of Science University of Bamenda Bamenda Cameroon

Interannual variability of the precipitation over West Africa Sahel is analyzed based on 32 years (1979-2010) from monthly and daily database of the Global Precipitation Climatology Project (GPCP). In this region, we found that there is a link between the West Africa Monsoon (WAM) and the daily means of the precipitation in the summer, unseasonal rains can occur in the transition seasons and even in the heart of the dry season. Rainfall is the most important element for agro-pastoral activities in this region. The 850-hPa wind and wind divergence structure show a maximum convection over Mountain region (Fouta-Djalon and Mont-Cameroon) which corresponds to the high precipitation and OLR observed in these regions. The trend and empirical orthogonal function (EOF) of the precipitation are presented, including the mid-July variability of the precipitation. The dominant EOF of GPCP precipitation accounts for around 25.3% of the variance with slightly large amplitude in the north while relatively small in the equatorial band respectively. The second and third EOF which accounts for 20.5% and 14%, describes a longitudinal contrast with a zonal gradient.

关键词： GPCP Precipitation West Africa Monsoon Inter Tropical Convergence Zone Trend