Unraveling the physics behind severe flash flooding in Indonesia’s new capital

Since the establishment of Indonesia’s new capital Nusantara (IKN), extreme hydroclimate has emerged as a serious environmental issue. One of the most notable events was the devastating flash flood that occurred on March 15-16, 2022, caused by heavy rain that lasted for four to six hours, causing severe damage and significant economic losses. Ta.

An international research team from Indonesia, the UK, the Netherlands and Australia identified mesoscale convective systems (MCS) as the main cause of this heavy rain. The study will be published in the journal Advances in Atmospheric Sciences.

Using high-resolution GSMaP (Global Precipitation Satellite Mapping) data, the research team shows that rainfall will peak during the MCS maturation period on the night of March 15, 2022, and decrease as it enters the dissipation period. I discovered it.

The study, led by Professor Eddy Hermawan from Indonesia’s National Research and Innovation Agency, investigated the effects of MCS phenomena, such as the Madden-Julian Oscillation (MJO, a major atmospheric phenomenon characterized by eastward pulses of clouds and clouds). Various environmental factors were also investigated. equatorial rainfall (usually repeating every 30 to 60 days), equatorial waves, and low-frequency fluctuations.

“Our findings demonstrate that while the MJO and equatorial waves play an important role in the early stages of MCS development by promoting moisture convergence in the lower boundary layer, local factors play a role in the mature and later stages of MCS evolution. This shows that it is more influential.” Professor Harmawan. “These results are supported by the opposite trajectory in the water transport analysis.”

This study reveals that the MJO and equatorial waves significantly contribute to the lower-level meridional water flux convergence during the pre-MCS and initiation stages, and their contribution accounts for up to 80% during the growth stage. Although the effects of La Niña and Asian monsoon on the MCS moisture supply were negligible, significant contributions from the residual period of water vapor budget during the MCS maturation and decay stages were observed.

“This means that local forcings such as small-scale convection, local evaporation, surface feedbacks, and topography also play a role in regulating the strength and duration of MCS,” said Ainur Rido, a scientist at the university. This suggests that it plays an important role.” Born in Reading, England.

This study improves our understanding of the potential causes of extreme rainfall in Nusantara and may help improve storm forecasting and risk management in the region. Looking ahead, the team plans to apply deep learning techniques to simulate and predict extreme weather events, such as heavy rains, related to the development of MCS in IKN and surrounding areas.