Jesika Ikrima, Nofi Yendri Sudiar, Trismidianto
On January 14, 2022, heavy rainfall occurred throughout southern Sumatra and even in western Java, which is known to be caused by convective cloud migration. This paper examines the role of convective clouds in increasing rainfall and even causing flooding along southern Sumatra and western Java using analytical methods. This study uses several data, namely brightness temperature (TBB) from Himawari, surface wind from CCMP, and several atmospheric parameters from ECMWF ERA5, as well as rainfall from GSMaP. The results of this research indicate that high rainfall along southern Sumatra and western Java is caused by the migration of convective clouds identified as MCC in the Indian Ocean near the Bengkulu Coastal. The interaction between strong low-level convergence and northerly and easterly surface winds supports the development of the MCC. The significant difference in geopotential height around the MCC area also gives rise to a jet stream that carries water vapor and strengthens the development of the MCC. When the MCC begins to disappear, a new convective system is formed, which is triggered by the outflow of a cold pool in the opposite direction to the land breeze at night. This new convective system induces mountainous convection on Sumatra Island, which produces large new convective systems. Strong ground-level convergent winds and low-level jets in areas of new convective formations trigger it to migrate to western Java, causing heavy rain along the areas it passes. Hovmoller's images of rainfall, clouds, vertical velocity, and convergence also show the movement and migration of clouds from the Indian Ocean near the Bengkulu Coastal to western Java. This article only examines one case; it would be very interesting if it could study many similar cases so that it could be a predictive study of the influence of MCC in the region. In this study, new convective growth caused by cold pool outflow is large-scale. This new, large-scale convective growth is not only triggered by cold pool outflow but is also supported by CENS. CENS winds trigger orographic rain clouds, which interact with new convective cells formed by cold pool outflow, thereby creating large-scale convective clouds. CENS also triggers the movement of new convective clouds migrating from Bengkulu to Lampung and the Sunda Strait and even toward Banten and Jakarta. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Padang (UNP), West Sumatra, Padang, Indonesia; Research Center for Climate and Atmospheric, National Research and Innovation Agency, Bandung, 40173, Indonesia
