Statistical analysis of sub-daily precipitation extremes in Singapore

Study region: The study was conducted with data from the city state of Singapore, a densely populated and highly urbanized island state close to the equator. Study focus: The study provides a basic statistical characterization of Singapore's precipitation regime. It quantifies the effects of daily and yearly cycles and the connections to the El Nino Southern Oscillation and Sea Surface Temperature on hourly rainfall amounts. A regional regression analysis was applied to detect trends in hourly and daily precipitation extremes. New hydrological insights for the region: Rainfall events in the early morning and in the afternoon exhibit different spatio-temporal characteristics. Singapore's precipitation activity is influenced by the El Nino Southern Oscillation, but not during the North-East Monsoon season. During the La Nina phase, seasonal precipitation totals are higher and the arrival of the most intense precipitation events is shifted towards morning hours. The rainfall regime has been changing during the investigation period from 1981 to 2010. Rainfall totals as well as hourly and daily extremes increased. The increase in daily extremes was the fastest, changing the temporal scaling of the extremes. The predicted changes in precipitation scaling towards higher daily sums have implications for the management of stormwater run-off. (C) 2015 The Authors. Published by Elsevier B.V.