Analysis of variability and trends of precipitation extremes in Singapore during 1980–2013

Abstract

ABSTRACTChanges in precipitation extremes in the tropical urban context is complex, where the precipitation activities are influenced by the combined effects of El Niño–Southern Oscillation (ENSO), global warming and local effects. This study presents a comprehensive framework to investigate the variability and trends in precipitation extremes in a tropical urban city‐state, Singapore, based on a set of extreme indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI). The long‐term trends in the precipitation extremes over the period from 1980 until 2013 are examined using an iterative‐based Mann–Kendall trend test. Besides, the relative importance of precipitation frequency and intensity in inter‐annual variability of wet‐day precipitation totals is investigated. Finally, the correlations between precipitation extremes and three potential large‐scale and local factors, i.e. ENSO, global mean temperature and local temperature are analysed based on linear regression method. Results reveal that annual wet‐day precipitation totals, as well as average wet‐day precipitation intensity, have increased significantly, accompanied by a significant increase in the frequency and intensity of precipitation extremes in Singapore. The inter‐annual variability of wet‐day precipitation totals is mainly dominated by precipitation intensity. Significant correlations are found between precipitation extremes and all the three factors, and the signature of local effects is more evident than global warming. These findings have implications for adaption planning and disaster risk reduction in Singapore in the context of global warming.