Assessment of the Characteristics of the Mesoclimates of the Major Cities in Kenya

Abstract

Urban areas generally alter the mesoclimates of cities as a result of reduced vegetation cover, altered urban geometry, record amounts of waste heat generation and the wind-channeling effects. The study objectives were achieved by assessing the changes and characteristics of the weather parameters; temperature, rainfall, wind, and humidity in three major Kenyan cities; Nairobi, Mombasa and Kisumu by determining the temporal variability and trend of the weather parameters. This study used monthly rainfall, temperature, wind, and humidity data acquired from the Kenya Meteorological Department (KMD) for Nairobi, Mombasa, and Kisumu for the period between 1990 to 2020. To quantify urbanization, the study used demographic data from the Kenya National Bureau of Statistics (KNBS), and Outgoing Longwave Radiation (OLR) obtained from NASA’s Giovanni 4.37 website. Once the data was determined to be homogenous, analysis followed by applying various graphical and statistical techniques, including trend analysis, correlation, and regression. Across all cities, minimum temperature revealed a significant positive trend. The rainfall and maximum temperature have a generally increasing trend. The wind patterns reveal a more spread out and faster wind speeds for all cities, indicating an altered wind pattern. When correlated we observe a general increase in minimum temperature - thus urbanization has an influence on the minimum temperature of the cities. The study results indicate the significant influence that modification of urban surfaces has had on the weather parameters of Nairobi, Mombasa and Kisumu.