Trends and Periodicities in Rainfall, Temperature, and Relative Humidity Datasets Over Ghana

Abstract

Francisca Martey and Kofi Anane-Fenin

This paper analyzed trends and periodicities in annual and seasonal rainfall, temperature, and relative humidity (RH) over Ghana using climatological datasets for twelve (12) synoptic stations spanning the periods of 30 to 52 years (1961–2010), obtained from the Ghana Meteorological Agency (GMet). The datasets were normalized by dividing with the long time mean, and grouped in decades. Findings show that 1961-1970 and 2001-2010 decades recorded significant wetter years, while 1981-1990 recorded relatively drier years within in the zones with bimodal rainfall seasons. However in the zone with mono-modal rainfall seasons wetter years occurred within the decades of 1981-1990 and 2001-2010. Furthermore, it is realised that, there is a cyclic pattern noted in the rainfall time series and a cycle of about 5 to 8 months for the Northern zone, 6 – 8 month for the middle belt and approximately 8 months for the coastal zone in the rainfall, temperature and humidity datasets suggesting a coherence in their relationship.

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