Study on the influence of Tropical Cyclone Kimi on wind speed and wave height in central and eastern Indonesian waters

Abstract

Tropical Cyclone (TC) Kimi was active from January 15 to 19, 2021 in Australian waters. TC Kimi activity does influence the atmosphere and ocean dynamics around it, including in central and eastern Indonesian waters, with the highest increase in local winds occurring in Sangihe (315.8%), Gorontalo (236.3%), Seram (236.3%) dan Manado (225.8%). On the other hand, Gorontalo experienced the highest increase of significant wave height during TC Kimi active, with 921.4% increase. In this study, we analyze wave height change in central and eastern Indonesian waters before TC Kimi was active, at the peak intensity of TC Kimi, and after TC Kimi dissipated by employing Simulating Waves Nearshore (SWAN) wave model. From spatial lagged correlation analysis between wind from TC Kimi and local winds in Indonesia, we obtained 12 locations that have positive lag and correlation, namely: Denpasar, Waingapu, Rote, Majene, Gorontalo, Manado, Sangihe, Sanana, Seram, Raja Ampat, Agats dan Merauke. From time series lagged correlation, the locations that have negative lag are Denpasar (-6 h) and Rote (-1 h), those with 0 h lag are Raja Ampat and Agats, and those with positive lag are Waingapu (+ 8 h), Majene (+ 10 h), Gorontalo (+ 14 h), Manado (+ 6 h), Sangihe (+ 15 h), Sanana (+ 7 h), Seram (+ 5 h) and Merauke (+ 6 h). Surface wind analysis during the development and early phase of TC Kimi shows wind flows from Sulawesi Sea, Maluku Sea, Halmahera Sea, and Banda Sea towards the TC Kimi system. When TC Kimi approaches its strongest intensity, there are low-pressure areas (Low) that are also active, including Low in the Philippines and in the Gulf of Carpentaria, while the wind flow towards TC Kimi appears to be disconnected. Low in the Philippines and the Gulf of Carpentaria, respectively, play a role in maintaining the high waves in the northern and southern waters of Indonesia. It indicates that TC Kimi plays a role in the initial increase of wind speed in Indonesia, which is continued by the presence of Low in their respective local areas.