North Atlantic Oscillation and Rainfall Variability in Southeastern Nigeria: A Statistical Analysis of 30 Year Period

Source:
By:Author(s)

DOI: https://doi.org/10.30564/jasr.v4i4.3843

Abstract: This study analyzed rainfall variability in Southeast region of Nigeria using graphical models, as well as using statistical approach to investigate any significant relationship between the global North Atlantic Oscillation (NAO) Index and the regional rainfall variability in region. The study was conducted in three States of Southeastern Nigeria namely, Abia, Ebonyi and Imo States that lie between Latitudes 40 40’ and 80 50’N and Longitudes 60 20’ and 80 50’E. Data for the study included 30 years (1988 - 2017) archival time-series monthly rainfall values for the three study States, acquired from Nigerian Meteorological Agency (NIMET), offices in the states, and Standardized values of NAOI (North Atlantic Oscillation Index) for the same period, which were collected from a website, on the NOAA Data Center, USA. In the data analyses, the first method was adopted by using graphs to illustrate mean annual rainfall values for thirty years. Coefficient of variability was employed in evaluating the degree of variability of values from the mean rate. The second analysis was accomplished using correlation models to ascertain any relationship between NAOI and rainfall in Southeast Nigeria. The results showed a significant variability of rainfall in the region from January to December (mean monthly) within the study period. A negative correlation value of 0.7525 was obtained from the correlation analysis, showing that the global NAO index and rainfall variability deviate in the opposite direction. Coefficient of multiple determinations (CMD) subsequently showed value of 0.031%, being the variation in rainfall as influenced by the global teleconnectivity, and this means that the NAO index has zero or no influence on rainfall variability in Southeast region of Nigeria. References:

[1]Nnaji A.O (2009): Implications of Current Climate Variation on Weather Conditions over Imo State, Journal of Biological and Environmental Sciences 2 22-23. [2]Nnaji AO (2001): Forecasting Seasonal rainfall for agricultural decision-making in Northern Nigeria” Agricultural and ForestMeteorological 107: 193-205. [3]Ayoade, J.O. (2004). Introduction to Climatology for the Tropics (2nd ed) Ibadan. Spectrum Books Limited. [4]Nnaji, A. O, Njoku, J. D and Ume, C. U. (2006). “Environmental Controls of rainfall over northern Nigeria: identification and verification”, Environmental Research and Development Journal, Faculty of Engineering and Environmental Sciences. Imo State University Owerri, Vol. 1 pp 86-93. [5]Ogungbenro, S. B., & Morakinyo, T. E. (2014): Rainfall distribution and change detection across climatic zones in Nigeria. Weather and Climate Extremes, 5-6, 1-6. DOI: https://doi.org/10.1016/j.wace.2014.10.002 [6]Okorie, F. C., Okeke, I. C., Nnaji, A. O., Chibo, C. N and Pat-Mbano, E. C. (2012): Evidence of Climate Varaibility in Imo State of southeastern Nigeria. Proceedings of the 5th International Conference on Water, Climate and Environment, BALWOIS 2012- 28May to 2 June 2012-Ohrid, Republic of Mecidonia, Journal of Earth Science and Engineering, 2 (2012) 544- 553. David Publisging Company, USA. [7]Okorie, F. C., Okeke, I. C., Nnaji, A. O., Chibo, C. N., Duru, P. N. (2011): Rainfall variability as evidence of Climate variation in Imo State of South-Eastern Nigeria. International Journal of Sustainable Development Vol. 4 Number, 9 (2011. [8]Okorie, F. C., Pat N. Duru, and Ifeyinwna C. Okeke (2013): Analysis of climate variability in Anambra State of Nigeria using 30 years rainfall and temperature data. Proceedings of Davos Atmospheric and Cryosphere Assembly DACA-13 July 8-13 2013 Davos, Switzerland, International Journal of Contemporary Studies Volume 1 No. 1 pp 232- 241. [9]Okorie, F. C. (2016): Precipitation Anomalies and its Effects in Port Harcourt Metropolis of Rivers State Nigeria. Proceedings of IUGG General Assembly, 22 June - 2 July 2015 Prague, Czech Republic, International Journal of Scientific & Engineering Research Volume 7, Issue 5, May 2016 Edition. [10]Okeke, I. C. and Okorie, F. C. (2009): Rural Water Sources and Quality Implications in Ogburu and Ihiala Communities of Anambra State, in Igbozuruike, U. M. et al; Rural Water Supply in Nigeria. Imo State University Owerri Cape Publishers Owerri, 2010, pp. 121-129. [11]Okorie, F. C (2020): Assessment of the Linkage between Rainfall variability and Arable Crop production in Enugu State Nigeria. Proceedings of African Climate Risks Conference (ACRC-2019) 7-9 October 2019. Addis Ababa, Ethiopia, American Based Research Journal, Vol-9-Issue-4 April-2020 ISSN (2304-7151) Pp 11-22. [12]Nnaji, A.O (1999): Climate Variation in Sub-Saharan Region of Nigeria: A Study of Rainfall Variability in Northern Nigeria. Unpublished PhD thesis, University of Florida Gannesville. [13]NOAA (2014): National Marine Fisheries Service. NOAA Current Fishery Statistics No. 2014. [14]Balmaseda MA, Trenberth KE, Kallen E (2013) Distinctive climate signals in reanalysis of global ocean heat content. Geophys Res Lett 40: 1754-1759. [15]Muhati FD, Ininda JM, Opijah FJ (2007) Relationship between ENSO parameters and the trends and periodic fluctuations in east African rainfall, J Kenya Meteorol Soc 1: 20-43. [16]Liguori, G. & Di Lorenzo, E. Separating the North and South Pacific meridional modes contributions to ENSO and tropical decadal variability. Geophys. Res. Lett. 46, 906-915 (2019). [17]Shilenje ZW, Ongoma V, Ogwang BA (2015) Relationship between the North Atlantic Oscillation Index and October- December Rainfall Variability Over Kenya, J Geol Geosci 4: 207. DOI: https://doi.org/10.4172/2329-6755.1000207 [18]Ogbodo, E. N. (2013). The fertility and mananegment imperatives of the degraded upland soils of Ebonyi state, Southeast, Nigeria. Niger. J. Soil Sci. 23 (2): 168-177. [19]NIMET (Nigerian Meteorological Agency, Nigeria) (2008). Climate, Weather and Water Information, for Sustainable Development and Safety, NIMET, 2008, Abuja. [20]Onweremadu, E. U. (2006). Application of Geographic Information System (GIS) on soils, land use and soil-related environmental problems in Southeastern Nigeria, PhD Thesis of the Department of Soil Science, University of Nigeria, Nsukka, Nigeria, 330pp. [21]Okorie, F. C. (2021). Climatic and Edaphic Factors for Crop Production in Southeast Nigeria, Lambert Academic Publishing, August, 2021. [22]Afiesimama, E. A, Pal, J., Abiodun, B. J, Gutowski, W. J and Adedoyin, A (2006). Simulation of West African monsoon using the Regcm3 Part I: Model validation and interannual variability, Theor. Appl. Climolotol. 86: 23-37. [23] Odjugo, A. O., (2010): Regional evidence of climate change in Nigeria. Journal of Geography and Regional Planning Vol. 3(6), pp 142-150.