Objective Criteria to Determine the Rainy Season Onset Date for the Central Highlands and Southern Vietnam

In this study, a new approach to selecting the Rainy Season Onset Date (hereafter denoted as RSOD) criteria is proposed and applied for Central Highlands and Southern Vietnam based on daily rainfall station data from 1979 to 2015. This approach bases on the similarity between station-based RSODs and regional-scale RSOD signal, obtained by applying Multi variable Principal Component Analysis (MPCA). The results show that these selected criteria can capture reasonably the heterogeneity of the start of the rainy season on both regional- and local-scale. The determined RSODs for the Central Highlands and the South are consistent with previous studies. It suggests the application potential of this approach in objectively determining the suitable RSOD criteria for each station (local-scale) in other regions.