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2 Acta Geophysica

2 2019

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Quantification of historical drought conditions over different climatic zones of Nigeria

Ogunjo Samuel, Ife-Adediran Oluwatobi, Owoola Eunice, Fuwape Ibiyinka

Acta Geophysica

2019

Vol. 67, no. 3

879--889

The impact of extreme climate such as drought and flooding on agriculture, tourism, migration and peace in Nigeria is immense. There is the need to study the trend and statistics for better planning, preparation and adaptation. In this study, the statistical and temporal variation of climatic indices Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) was computed for eighteen (18) stations covering four climatic zones (Sahel, Midland, Guinea Savannah and Coastal) of tropical Nigeria. Precipitation, minimum and maximum temperature from 1980 to 2010 obtained from the archives of the Nigerian Meteorological Services were used to compute both the SPI and SPEI indices at 1-, 3- 6- and 12-month timescales. The temporal variation of drought indices showed that droughts were more prominent at 6- and 12-month timescales. SPI and SPEI were found to be better correlated at longer timescales than short timescales. Predominant small, positive and significant trend across the region suggest an increasing trend due to climate change.

Analysis of heterogeneity of aridity index periodicity over Lebanon

Telesca Luciano, Shaban Amin, Awad Mohamad

Acta Geophysica

2019

Vol. 67, no. 1

167--176

Lebanon, with its geographic location facing the Mediterranean Sea and dominant rugged topography, is characterized by a strong climatic variability even between zones located few kilometres apart. The investigation of the climatic indices is necessary to delineate such diverse climatic situation over Lebanon. In this context, this paper investigates the periodic behaviour in annual Emberger aridity index (AIE) of 14 weather stations in representative sites of Lebanon. The AIE indicates that the dominant climate of Lebanon, which is mainly varying from humid to semi-arid, follows cyclonic meteorological patterns. The periodicities of AIE identified by using a robust technique seem almost altitude related and range between 2 and 21 years. The geographic distribution of periodicities implies two major zones in the northern and southern parts of Lebanon, being featured by longer and shorter periodicities, respectively. The formation of these two periodicity zones can be related to regional climatic zoning. The remarkable diversity in periodicity indicates predominant microclimates with specified cyclonic climate that characterizes Lebanon’s climate rather than a merely existence of climate change.