The Diurnal Variation of Rain Intensity in Malaysia for Monsoon Region using TRMM Satelit Data

Abstract

Malaysia is located in an equatorial region with high and stable temperatures, high humidity, and rainy throughout of the year. The rains are caused by the monsoon regime and influenced by local topography. However, Malaysia is near the Equator and surrounded by the sea, there is no real dry season. The weather in Malaysia is mainly affected by two monsoon regimes which is the Southwest Monsoon (MBD) from May to September, while the Northeast Monsoon (MTL) from November to March for every year. The sea in Malaysia are causing the effects of sea breeze and land breeze that have a huge impact on wind patterns. The abundant rainfall in Malaysia which is suitable in this study is to analyze the 3B42 rainfall data from Tropical Rainfall Measuring Mission (TRMM) and 14 study areas including of 8 areas from Peninsular of Malaysia (SM) and 6 areas from East of Malaysia (MT) for the period of 11 years of data from 2009 to 2019. This paper is to study the intensity of diurnal rainfall according the temporal and spatial data using Segal models which is conversion the 1-minute rainfall interval in Malaysia. The Segal model is the best model for conversion of rainfall data for Malaysia. This paper also analyses the rainfall data in Malaysia. The conversion of 1-minute rainfall interval data can give the statistical stability of rainfall distribution that influenced by the diversity of landforms, the movement of monsoon winds, and the latitude of surface areas. The result of this study show that Kuching, Sarawak received 1-minute rainfall data at 175.25mm/hour with the highest annual rainfall of 4641.34mm in the entire study area within Malaysia. The lowest 1-minute rainfall data for SM is Cameron Highlands, Pahang which came up to 103.09mm/hour while the highest 1-minute rainfall data is Kota Bahru, Kelantan at 171.13mm/hour. Kota Bahru study area also received the average of highest annual rainfall data for SM which is at 3013.33mm. Cameron Highlands is located near Titiwangsa Range, where the backbone of SM is located, and the area is protected by strong MTL winds. The results found that the lowest average daily, monthly, and annual rainfall is Mersing, Johor at 1992.98mm for the entire study area. The pattern of rainfall distribution as overall show the east coast area of SM and the entire state of Sarawak received heavy rainfall affected by MTL winds and have the same average diurnal rainfall pattern which has two maximum rainfall points per day. The amount of rainfall distributions is different from one area to another and changes from time to time. The El Nino and La Nina phenomenon known as the El Nino Southern Oscillation (ENSO) is also affecting the rainfall distribution in Malaysia because of the sea surface temperature that keeps changing in the equatorial Pacific Ocean. Almost the entire study area were affected by the ENSO phenomenon in 2015 and 2016. This rainfall distribution study in Malaysia is very useful and helps government and private sectors to make prepararations for the seasonal rainfall, flood, and drought.