Abstract:
This study was carried out to assess the variations of Reference Evapotranspiration (ETO also denoted with RET) calculated
using FAO-56 Penman Monteith model of two locations Asaba and Uyo and evaluate its relationships with the variations of other climatic
parameters. Meteorological data of forty one years (1975-2015) and thirty five years (1981-2015) period for Asaba and Uyo, respectively
gotten from Nigeria Meteorological Agency, Abuja were used. It was observed that the variations of Evapotranspiration (ET) in both
locations were in line with two seasons (rainy and dry) normally experienced in Nigeria having its highest value in March (4.8 mm/day) for
Asaba and for Uyo in February (4.5 mm/day); and its lowest value in August (3.1 mm/day) for Asaba and in July (2.9 mm/day) for Uyo. ET
variation when compared with other climatic variables in both locations was observed to have the same trend with maximum temperature,
solar radiation and sunshine hours. It also has the same variation with minimum temperature though with slight deviation. It was observed
that ET variation is inversely proportional to the variation relative humidity. Wind speed displayed relatively small variation in its trend over
the study period and is not in line with the variations of ET
