Observed rainfall trends over Singapore and the Maritime Continent from the perspective of regional-scale weather regimes

AbstractStraddling the Asian-Australian monsoon region, the Maritime Continent (MC) experiences substantial rainfall variations from diurnal to interannual and longer timescales. In this study, rainfall over Singapore and the wider MC region are analyzed using objectively identified weather regimes. Eight regional-scale weather regimes are derived by k-means clustering of local vertical profiles of zonal and meriodional winds, temperature and specific humidity extracted over Singapore from ERA-Interim reanalysis data for the period December 1980 to November 2014. The composite synoptic flow and rainfall patterns over the region show that the weather regimes correspond to the seasonal migration of the Inter-Tropical Convergence Zone (ITCZ) across the Equator. For Singapore, the regimes depict seasonal rainfall variability by capturing the alternating dry and wet phases of the prevailing local monsoon and transition periods associated with the regional-scale ITCZ movement. Following previous work, the regim...