Long Term Microscale Decadal Analysis of Coastal Rainfall Pattern: An Indication of Microclimatic Variation in South India

Abstract

There are drastic variations in the intensity and the pattern of rainfall and temperature globally. The variations thus reflect the variation in the microclimatic signatures. The current study aims to assess the climatic changes in the coastal region of Ramanathapuram using the monthly rainfall and temperature average along the coastal region. The microscale rainfall and temperature trend have been analysed for three decades (30 years), representing 1990 to 2019. The study was divided into three different periods: first (1990-1999), second (2000-2009), and the third decade (2010-2020). The study infers that 467 km2 of the area receives an average of 676 mm of rain in decade-I. In decade-II, 39 km2 of the area is noted with 637.6 mm rainfall, 48 km2 of the study area is reported to have 821 mm rainfall, and only 29 km2 area receives normal rainfall of 992 mm, but 351 km2 receives “excess” rainfall of above 1000 mm. In decade-III, less than 750 mm rainfall is recorded at 202 km2, with 43 km2 recorded “deficit” rainfall, and 24 km2 area received an “excess” rainfall. The variation in the amount of rain during the recent period was observed. Similarly, the temperature was comparatively elevated during the Ist Decade (1990-1999). The intensity of rain events, number of rainy days and frequency of rainfall reflected variations. The land surface temperatures also indicated minor variations and increased inter-monsoonal periods. The variation in the rainfall amount, the shift in monsoonal periods and the change in temperature indicate the microclimatic variation in the region.