Comparison of Mann–Kendall and Şen’s innovative trend method for climatic parameters over Nigeria’s climatic zones

Abstract

Creating innovative ways for the identification of trends is a very vital part of atmospheric studies. Different climatic locations present their unique variations, calling for the dynamism of trend analysis. In addition to the widely adopted Mann–Kendall (MK) trend test, the new Şen’s innovative trend analysis (ITA) method has been applied to analyze the trends of refractivity related (atmosphere pressure—AP, vapour pressure—VP, ambient temperature—T) and equivalent potential temperature—EPT related parameters (mixing ratio of air—R, absolute temperature at the lifting condensation level—TL, potential temperature—PT). This analysis was perfomed using 40 years’ data (1981–2020) from 4 stations from each climatic zone of Nigeria (Calabar—Tropical monsoon, Ibadan—Tropical Savannah, Kano—Warm semiarid climate, and Kukawa—Warm desert climate). The MK test detects trends in 16 of the total 32 parameters across all locations/climatic regions. The Sen’s ITA method however, detects trends for an average of about 27 parameters for all low, medium and high values. MK results for parameters across climatic zones that show no trends are demystified by the Sen’s ITA method with increasing and/or decreasing trends across low, medium or high values; consequently, parameters that show trends from the MK test have monotonically increasing trends (where all low, medium and high values are above the 1:1 (45°) line) for the Sen’s ITA test. Other comparisons between both methods were outlined and explained; correlation heat maps were used to show the relationship between all parameters for each climatic location, describing the effect of climate on the variations of these parameters. The low, medium and high values revealed from the Şen’s ITA method can be informative for telecom and renewable energy applications, guiding engineers and system designers to understand the trends within range of values for a particular climatic parameter.Graphical abstractThe movement of air parcels and amount water vapour in the atmosphere is a very vital concept to consider in atmospheric dynamics. The climatic parameters shown in the image are all related to one or both of the aforementioned conditions. A comparison of the Mann–Kendall test and Sen’s Innovative trend method has been applied to study these parameters over the four climatic zones of Nigeria. It has been observed that the Sen’s test identifies trends for low, medium and high values, giving more information about the trends and how they can be applied for engineering designs and renewable energy.