The Modulation of Asia-Australia Monsoon to Mesoscale Convective System on East Java Maritime Continent

Indonesian Maritime Continent, with strong convection activity, triggers the formation of clouds which can evolve and develop into mesoscale systems in the form of MCSs (Mesoscale Convective Systems). The shape of MCSs in tropical regions can be circular and linear. MCSs based on spatially, can be classified into the Meso-β and Meso-α. The length of 25-250 km included in to Meso-β scale. The length of 250-2500 km included in to Meso-α scale. MCs can cause disasters and significant damage, including gale wind and extreme rain. MCSs is influenced by monsoon. Maximum frequency of MCSs in Indonesia follows the seasonal radiation cycle and its movement pattern of the Asian and Australian Monsoon, including the East Java region. Observational rainfall data for 29 years (1995-2023) from 5 meteorological observation stations is used to determine when heavy and extreme rain. Weather satellites infrared are used to identify MCSs based on physical characteristics, that are cloud shield and interior cold cloud based on time of heavy and extreme rain, image pixels to determine diameter and area, cloud lifetime, eccentricity to determine shape, and point center of mass to determine tracking of cloud. Zonal and meridional wind data at 850 mb to determine Australian Monsoon Index. Known that Asian-Australian monsoon has a less significant influence on the frequency of MCSs in the East Java region. Monsoon index has the same pattern and phase as the frequency of MCSs based on a monthly and seasonal. Maximum frequency of MCSs occurs during transition from the Australian to Asian monsoon and minimum frequency of MCSs occurs during the transition from Asian to Australian monsoon. Frequency of occurrence of Meso-β dominates over Meso-α and the most dominant life duration is 1-3 hours. Spatial distribution of Meso-β is more even than Meso-α which only occur at certain times and locations. The region that has the most dominant intensity of MCSs is Southwest East Java.