The influence of El Niño–Southern Oscillation on boreal winter rainfall over Peninsular Malaysia

Abstract

Multi-scale interactions between El Nino-Southern Oscillation (ENSO) and the Boreal Winter Monsoon contribute to rainfall variations over Malaysia. Understanding the physical mechanisms that control these spatial variations in local rainfall is crucial for improving weather and climate prediction and related risk management. Analysis using station observations and ERA-interim reanalysis reveals a significant decrease in rainfall during El Nino (EL) and corresponding increase during La Nina (LA) particularly north of 2ºN over Peninsular Malaysia (PM). It is noted that the southern tip of PM shows a small increase in rainfall during El Nino although not significant. Analysis of the diurnal cycle of rainfall and winds indicates that there are no significant changes in morning and evening rainfall over PM that could explain the north-south disparity. Thus, we suggest that the key factor which might explain the north-south rainfall disparity is the moisture flux convergence (MFC). During the December to January (DJF) period of EL years, except for the southern tip of PM, significant negative MFC causes drying as well as suppression of uplift over most areas. In addition, lower specific humidity combined with moisture flux divergence results in less moisture over PM. Thus, over the areas north of 2ºN, less rainfall (less heavy rain days) with smaller diurnal rainfall amplitude explains the negative rainfall anomaly observed during DJF of EL. The same MFC argument might explain the dipolar pattern over other areas such as Borneo if further analysis is performed.

Analyzing Future Rainfall Variations Over Southern Malay Peninsula Based On CORDEX-SEA Dataset

“…Most of the peninsula is affected by two monsoons, including southwest monsoon (from May to September) and northeast one (from November to March), with Singapore location having slightly delayed month in each monsoon (Suhaila et al, 2010;Li et al, 2019). The climate of the study area is strongly affected by the monsoon winds and also the global effects (like EL Niño-Southern Oscillation), making it susceptible to increased risks of flooding and droughts under climate change conditions (Tangang et al, 2017;Richard and Walsh, 2018). For the convenience of spatial description, we adopt the eight climatic zones delineated by Wong et al (2016), to cover the study area and highlight climate change impacts.…”

Analyzing future rainfall variations over southern malay peninsula based on CORDEX-SEA dataset

“…Most of the peninsula is affected by two monsoons, including southwest monsoon (from May to September) and northeast one (from November to March), with Singapore location having slightly delayed month in each monsoon (Suhaila et al, 2010;Li et al, 2019). The climate of the study area is strongly affected by the monsoon winds and also the global effects (like EL Niño-Southern Oscillation), making it susceptible to increased risks of flooding and droughts under climate change conditions (Tangang et al, 2017;Richard and Walsh, 2018). For the convenience of spatial description, we adopt the eight climatic zones delineated by Wong et al (2016), to cover the study area and highlight climate change impacts.…”