DIURNAL AND SEASONAL VARIATIONS OF MESOSCALE CONVECTIVE SYSTEMS PRECIPITATION AND THEIR INFLUENCE ON RAINFALL PATTERNS IN THE INDONESIAN MARITIME CONTINENT

• Main Author: Adib Azka, Mukhamad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/84973
• Institution: Institut Teknologi Bandung

Mesoscale Convective Systems (MCSs) are organized of convective and stratiform clouds that combine into complex storm systems and produce mesoscale circulation. MCSs plays an important role in the hydrological cycle and global circulation through the distribution of water and energy in the atmosphere. Apart from that, MCSs often produces extreme weather such as thunderstorms, strong winds, turbulence, heavy rain, and even floods. The Indonesian Maritime Continent (IMC) is a region that is very favorable for MCSs development. An important variable from MCS that has positive and negative impacts is precipitation. MCS and non-MCS precipitation have different characteristics due to differences in the size and duration of the clouds produced. One of the impacts of differences in precipitation in the BMI area is seasonal rainfall patterns. It is not yet known with certainty the impact of differences in MCS and non-MCS precipitation on rainfall patterns. This study aims to determine the diurnal and seasonal variations in MCS and non-MCS precipitation and determine their impact on rainfall patterns at BMI. MCS identification and tracking uses the flexible object tracker (FLEXTRKR) algorithm. Diurnally, MCS precipitation predominantly occurs from 00.00 to 06.00 local time (WIB), whereas non-MCS precipitation predominantly occurs from 12.00 to 18.00 local time (WIB). MCS precipitation is 2 times higher than non-MCS precipitation, even more so in the December to February (DJF) season. The South Indian Ocean region of Sumatra and the Western Pacific Ocean are affected by MCS precipitation in all seasons. The contribution of MCS precipitation reaches 80% in almost all BMI areas, with the largest contribution from the meso-? circular convective system (M?CCS) type at around 50%. Meanwhile, the most dominant intensity of heavy rain is produced by the mesoscale convective complex (MCC) type. Non-MCS precipitation predominantly occurs in the Nusa Tenggara, Sulawesi, Maluku Islands and parts of Papua. The smaller the size of the MCS, the more dominant the distribution of events and the intensity of heavy rainfall produced over land. MCS precipitation has a very dominant contribution in influencing rainfall patterns in monsoonal and equatorial regions. Meanwhile, nonMCS precipitation has a dominant contribution in areas with local rainfall patte