Analysis of high waves and coastal flooding event in Manado in mid-January 2021 (meteotsunami perspective)

Abstract

Meteotsunami is atmospheric-induced ocean waves at the frequency of tsunami waves (2 minutes-2 hours). On January 17, 2021, the high waves tsunami-like due to lousy weather superimposed with the high tide were reported hitting the coastal area of Manado City, North of Sulawesi. This research examined the characteristic of that tsunami wave-like phenomenon. The sea level, atmospheric data (i.e., wind and air pressure), and weather satellite imagery were used in this study. The sea level, air pressure, and wind data were filtered to remove the low-frequency signal to obtain the amplitude of the high-frequency signal. The results showed that a high-frequency sea level signal’s maximum wave height (peak to trough) is up to 0.4 m. This condition responded to the increase in high-frequency maximum wind speed reaching 11 m/s associated with the convective system, such as the Cumulonimbus cloud system, detected 10 hours before the maximum high-frequency sea-level event. These circumstances meet the meteotsunami criteria, but the other parameter, such as air pressure, is not.