Determination of Refractivity Gradient and Geoclimatic Factor Using Radiosonde Data and Inverse Distance Weighting Spatial Interpolation for Missing Data

摘要

In this paper, point refractivity gradient and geoclimatic factor are determined using radiosonde data on meteorological parameters obtained in Calabar, Nigeria. The meteorological parameters used are air temperature, pressure and humidity obtained from the radiosonde data archive of Nigerian Meteorological Agency. In view of the poor spatial resolution of radiosonde data, inverse distance weighting spatial interpolation technique is used to obtain the missing data at certain height of interest in the study. The results obtained showed that the point refractivity gradient and geoclimatic factor showed monthly and seasonal variations. Specifically, Calabar has annual average Point Refractivity Gradient (dN) and Geoclimatic Factor (K) of -125.508 N-units/Km and 6.53762E-05 respectively. The largest dN value of -25.4683 N-units/Km occurred in May whereas the smallest value of -305.2692 N-units/Km occurred in November. Furthermore, there is higher value of point refractivity gradient in the rainy season than in the dry season whereas there is lower value of geoclimatic factor in the rainy season than in the dry season.