The seasonal and diurnal trends of surface refractivity were derived using International Telecommunication Union Radio assembly model (ITU-R P.453-13) in two locations of entirely different vegetation characteristics in Nigeria. Atmospheric refractivity is a function of temperature, pressure as well as humidity. These meteorological variables were applied to the model to compute the refractivity parameter. Atmospheric refraction or refractivity is a key component in radio wave propagation. Real-time measurement data from a network of ground-based automatic weather station (AWS) installed at 3 m height were used and the monthly trends of surface refractivity at both stations (Lagos and Anyigba) were derived; the trends showed a month-to-month variability signifying the dynamic nature of the Earth’s atmosphere. The monthly trends in both stations show high refractivity values in the rainy months and low refractivity values in the dry months. A drop in refractivity value was observed in Lagos in the month of August, due to the cessation in rainfall as a result of a phenomenon referred to as August break. The diurnal variations were also determined and results obtained showed that the lowest refractivity value in the dry season observed in Lagos is higher than the highest refractivity value in rainy season observed in Anyigba. This is attributed to the fact that Lagos is located along the coast of the South Atlantic Ocean, therefore, the monsoon has a direct influence on its atmosphere, while Anyigba is an inland station with a mixture of savannah vegetation. Overall, the diurnal variations show high values in the morning and evening hours and low values in the afternoon hours in both seasons in Anyigba, while in Lagos we observed a surprising result, such as a rise in refractivity value at pre-noon and a post-noon drop. This unacquainted observation is probably due to excessive precipitation in the area caused by the influence of massive emissions from the South Atlantic Ocean, these emissions are mainly a result of the trapped heat due to warming of surface water.

中文翻译：

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使用地基自动气象站的热带环境中表面折射率的季节性和昼夜趋势

使用国际电信联盟无线电组​​件模型 (ITU-R P.453-13) 在尼日利亚完全不同植被特征的两个地点得出了表面折射率的季节性和昼夜趋势。大气折射率是温度、压力和湿度的函数。这些气象变量被应用于模型以计算折射率参数。大气折射或折射率是无线电波传播的关键组成部分。使用安装在 3 m 高度的地基自动气象站 (AWS) 网络的实时测量数据，并推导出两个站（拉各斯和安尼格巴）的月表折射率趋势；趋势显示出每月的变化，这表明地球大气的动态性质。两个站点的月度趋势都显示雨季的高折射率值和干旱月的低折射率值。由于被称为八月中断的现象导致降雨停止，8 月份在拉各斯观察到折射率值下降。还确定了昼夜变化，获得的结果表明，在拉各斯观察到的旱季最低折射率值高于在 Anyigba 观察到的雨季最高折射率值。这归因于拉各斯位于南大西洋沿岸，因此季风对其大气有直接影响，而安尼格巴是一个混合热带草原植被的内陆站。全面的，昼夜变化在 Anyigba 的两个季节都显示出上午和晚上的高值和下午的低值，而在拉各斯，我们观察到了令人惊讶的结果，例如中午前和中午后的折射率值上升降低。这种不为人知的观察很可能是由于南大西洋大量排放的影响导致该地区降水过多，这些排放主要是地表水变暖导致的滞留热量的结果。