An Analogy of the Rainfall Trend over the Western Ghats and Their Surroundings

Abstract

The study examines the monthly variation of rainfall in lower atmospheric level of different locations in Western Ghats (W.G.), and its nearby cities in the states of Kerala, Karnataka, and Tamil Nadu. It uses high resolution gridded rainfall data from India Meteorological Department (IMD) with a resolution of 0.250 × 0.250 (approximately 25km×25km), which are used to analyze the trend of changing climate on the distribution of rainfall (measured in millimeters) in different topographical zones of the Western Ghats and their nearby cities in India, from 2016 to 2023. Additionally, datasets of wind direction from the power access data portal of NASA’s MERRA-2 and intensities of El Niño & La Niña reports from the Golden Gate Weather Services portal were also taken into account for this study. Daily rainfall data have been analyzed as monthly, seasonal, and annual variations. It indicates that there is an increase in pre-monsoon, post-monsoon and winter rainfall, while monsoon rainfall decreased in the selected study areas. It has been observed that Karkala in Udupi received the highest mean rainfall in the month of August, and Parameshwarpuram in Nagercoil received minimum mean rainfall in the same month over Western Ghats (W.G.). Also, based on the variation of rainfall trend in the selected regions, the locations can be classified as low rainfall, moderate rainfall, and heavy and/or very heavy rainfall region with reference to the Western Ghats (W.G.).