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Tropospheric scintillation depends significantly on any location's prevailing weather condition, and its variation must be statistically analyzed to ensure accurate fade margin determination. This study examines the distribution of Ku-band amplitude scintillation across selected locations in tropical Nigeria. Eight years of daily averaged data of surface temperature and relative humidity were employed for computing scintillation intensity (σ) and amplitude (χ) using international telecommunications union recommended model across eighteen (18) stations, that are subdivided into four (4) regions and spread over tropical Nigeria. The data, spanning January 2010 to December 2017, were obtained from the archive of the European center for medium-range weather forecasts (ECMWF) with a resolution of 0.125° by 0.125°. Three (3) years of in-situ data of concurrently measured satellite radio beacons and primary radio-climatic parameters at Akure (7° 17′ N, 5° 18′ E, 358 m), South-west Nigeria, were employed for comparison and validation. Statistical analyses involving time series, probability density, and cumulative distribution functions were performed on the scintillation dataset annually. Results indicate that the magnitude of tropospheric amplitude scintillation varies across different locations; nevertheless, it exhibits a similar distribution pattern characterized by the generalized extreme value (GEV) probability density function (pdf). The study has shown the need to incorporate the scintillation component into the fade mitigation architecture of telecommunication systems in tropical Nigeria while considering its regional variability. Also, experimental validation of the observations raised in this study should be encouraged at all the locations for better prediction accuracy. [ABSTRACT FROM AUTHOR]

An intense mesoscale convective system (MCS) in the Guinea Coast region caused one of the highest ever recorded daily rainfall amounts at the Nigerian station Abakaliki on 12 June 2016 (223.5 mm). This paper provides a detailed analysis of the meso- and synoptic-scale factors leading to this event, including some so far undocumented dynamical aspects for southern West Africa. The MCS formed over the Darfur Mountains due to diurnal heating, then moved southwestward along a mid- to lower-tropospheric trough, and developed into a classical West African squall line in a highly sheared environment with pronounced midlevel dryness. Strong moisture flux convergence over Nigeria prior to the MCS passage led to extreme values in precipitable water and was caused by the formation of a local, short-lived heat low. According to the pressure tendency equation, the latter resulted from tropospheric warming due to MCS-forced subsidence as well as surface insolation in the resulting almost cloud-free atmosphere. In this extremely moist environment, the MCS strongly intensified and initiated the formation of a lower-tropospheric vortex, which resulted in a deceleration of the MCS and high rainfall accumulation at Abakaliki. Following the vorticity equation, the vortex formation was realized through strong low-level vortex stretching and upper-level vertical vorticity advection related to the MCS, which became "dynamically large" compared to the Rossby radius of deformation. Eventually, moisture supply and lifting associated with the vortex are suggested to promote the longevity of the MCS during the subsequent westward movement along the Guinea Coast. [ABSTRACT FROM AUTHOR]