Climatology of Guinea: Study of Climate Variability in N’zerekore René Tato Loua, Maoro Beavogui, Hassan Bencherif, Alpha Barry, Zoumana Bamba, Christine Amory-Mazaudier To cite this version: René Tato Loua, Maoro Beavogui, Hassan Bencherif, Alpha Barry, Zoumana Bamba, et al.. Clima- tology of Guinea: Study of Climate Variability in N’zerekore. Journal of Agricultural Science and Technology (JAST), University of Tarbiat Modares, 2017, 7 (4), 10.17265/2161-6256/2017.04.001. hal-01634369 HAL Id: hal-01634369 https://hal.univ-reunion.fr/hal-01634369 Submitted on 14 Nov 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Climatology of Guinea: Study of Climate Variability in N’zerekore Rene Tato Loua1, 2, 4, Maoro Beavogui1, Hassan Bencherif2, 3, Alpha Boubacar Barry1, Zoumana Bamba4 and Christine Amory Mazodier5, 6 1. Guinea Weather Service (DNM), Conakry, BP 566, Guinea 2. Laboratoire de l’Atmosphère et des Cyclones, Université de La Réunion, UMR 8105, CNRS, La Réunion, France 3. School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban, South Africa 4. Scientific Research Center of Conakry Rogbane (CERESCOR), Conakry, BP 1615, Guinea 5. Laboratoire de Physique du Plasma, Université Pierre et Marie Curie, UMR 7648, Paris, France 6. International Center for Theoretical Physics (CTP), Strada Costiera 11, I-34151 Trieste, Italy Abstract: N’zerekore is a geographical region of Guinea, which houses a weather observatory located at longitude 8.8°, latitude 7.7° and altitude 475 m. This region is of major socio-economic interest for the country. The climatological study of this region shows the variability of each parameter. The objective of this study was to analyze meteorological parameters trends and to assess the space-time evolution of some agro-climatic risks related to the main trends observed in the meteorological parameters regime of this region. In this study, programming tools were used for processing and analyzing meteorological parameters data, including temperatures, rains, wind, evaporation and storms measured in this observatory from 1931 to 2014. The interannual, annual and daily variations of these parameters were obtained, as well as temperature, precipitation anomalies and agroclimatic indexes trends. The analyzing of these variations explained that September is the rainiest months, and the year 1932, 1957 and 1970 are normal, rainy and dry year, respectively. The evaporation increased since 1971 from January to March and November to December. A positive temperature anomaly was observed since 1973 with the maximum 26-33 °C and the minimum 16-21 °C. A dominant westerly wind with a speed of 2.6 m/s was determined. Agro-climatic parameters in N’zerekore have high variability. From 1931 to 2014, three major periods can be distinguished: a wet period from 1931 to 1977, a dry period from 1978 to 1994 and rainfall variability from 1995 to 2014. The trend of these parameters explains the impact of climate change in this part of the world. This is exacerbated by human activity (deforestation), thus mitigation measures are necessary. It would be useful to extend this study throughout the country. 1. Introduction placed for some time in the center of the concerns of scientists and policy makers in the world [2]. Climate Guinea is a country with great agro-sylvo-pastoral change and variability issues have long been studied potential. Their exploitation requires an agricultural in large dimension, while results show that climates planning effort, which can not be done without a good vary from one country to another and sometimes understanding of the climate, especially the variability within the same country because of the existence of and distribution of rainfall [1]. Because of their several different ecosystems [3]. immediate and lasting impact on the natural The most important issue, especially for West environment and man, the questions of climate change Africa than in other regions of the world, is the study and variability (temperature and precipitation) are of climate change and variability at local scales, so that policy makers can adapt to any increase in risks Corresponding author: Rene Tato Loua, Ph.D. student, research fields: meteorlogy, physics of atmosphere, remote and take advantage of any positive effect which might sensing, GIS and natural risks. be resulted in [4]. Agriculture is typically the most important sector in In Guinea, precipitations are the most important the economy of developing countries, especially in the climate parameter for both populations and least developed countries (LDCs) and small island ecosystems, and thus define different natural regions developing states (SIDS). The practice of agriculture [5, 6]. Consequently, the economy is mainly oriented and the productivity of the agricultural systems towards the activities that depend on climate, depend heavily on prevailing rainfall and temperature including rainfall [7]. It is thus that in a context of patterns. So, the agricultural sector and other sectors great vulnerability and limited capacity, a slight are very vulnerable to climate change [11]. change in rainfall patterns could instantly affect The semi-arid and sub-humid areas in West Africa hundreds of thousands of vulnerable people who possess highly variable and erratic rainfall which depend on rain to live [8]. The Guinea is composed of affects agricultural productivity. Agricultural practices 33 prefectures, while this study is focused on have had to adapt to these climate risks, because very N’zerekore prefecture (Fig. 1). Indeed, the population little land is irrigated. Consequently, any change in the of N’zerekore is predominantly rural, and the current climate threatens agricultural productivity and performance of operated production systems the survival of many populations in West Africa. (agriculture and livestock) is closely subject to climate. Knowledge of the variability of these parameters is The agroclimatic characteristics in any country or very important for the planning of agricultural activities. subnational region are primarily determined by Also, knowing of agroclimatic characteristics can be intra-year distributions and inter-year variations in used to strengthen the techniques of seasonal rainfall rainfall and temperature [9, 10]. forecast and agro-climatic projections in the region. However, the climate is rarely seen as a precious Thus, in this study, the programming tools were used to natural resource for economic and social growth until analyze and characterize the climate variability and a major event disrupts energy production or agroclimatic parameters observed in N’zerekore agriculture or health risk of the population. synoptic station 1931 to 2014. Fig. 1 Localization of N’zerekore in Guinea. 2. Materials and Methods days after the start of the rainy season; the length of dry sequences of flowering (dry sequence observed In this study, the climatological data cover the during flowering-maturation); the number of rainfall period from 1931 to 2014, recorded by weather days recorded during the growing season; the total observatory of N’zerekore (7.7° N, 8.8° W), and rainfall of the growing season; heavy daily rainfall extracted from the well-preserved archives of Guinea during the growing season; National Weather Service. (3) Trend and variability of the maximum and Among the Guinea observatories, N’zerekore minimum temperature; meteorological data are the subject of national, (4) Storms frequency; regional and global uses, so they were used for an (5) Wind speed and direction. international study [12]. As for the variability of The average of 1961-1990 has being used as agroclimatic parameters, the daily rainfall data from reference period in variability analysis of parameters. 1961 to 2013 of the synoptic observatory of N’zerekore were used. 3. Results and Discussion The Informatics Centre of the National Weather 3.1 Major Temporal Trends in Rainfall Patterns Service has developed robust PC uses CLICOM software for managing its climate data. Other software, 3.1.1 Interannual Variation in 1931-2014 such as Climsoft, Excel, Word and INSTAT+, were The analysis of the interannual variation of total used for data processing and presentation of results. rain shows two periods of oscillation around the Qgis were used for map editing. The observations of normal value (1,880 mm) with a pitch of five years various meteorological elements did not start at the between 1931 and 2014 (Fig. 2). Deficit years (1969) same time, and due to measurement interruptions for are below the normal, surplus years (1957) are under some data, calculated climatic parameters do not relate the normal and years on the normal value are normal to the same period. But the minimum period years (1932). recognized for describing the climate is 30 years It should be noted that during the long period of 20 according to World Meteorological Organization years of deficit, only the years 1989 and 1990 record a (WMO), and the period used is sufficient to consider slight rainfall excess. The height varies between 1,473 an appreciable climate studies in N’zerekore. mm and 2,539 mm in 1970 and 1957 with an average The softness or harsh climate is confirmed by the of 1,879 mm. This result is consistent with that found variation of the observed values of climatic by Bangoura [13]. parameters in relation to the average during the period. 3.1.2 Annual Variation in 1931-2014 Analysis of these variations and interpretations of the N’zerekore rainfall is variable. The total rainfall of results are subject of the present work. 1,878.7 mm is observed in 138 d in monthly average Statistical analysis of climatological data covers: by year (Fig.