A. Lumban Gaol¹ , A. Kristianto² , F. Novico³ , A. Fadlan²

¹Indonesian Agency of Meteorology Climatology and Geophysics (BMKG)
²Indonesian State College of Meteorology Climatology and Geophysics
³Marine Geological Research and Development Center

Abstract:

The Dahlia Tropical Cyclone occurred during the period November 27th until December 2nd, 2017, with increasing strength in the West Indian Ocean near the Bengkulu Sea. Altimetry satellite data was used to determine the condition of sea level anomaly and showed an increased sea level anomaly of about 0.3-0.4 meters, but experienced a less significant change from the previous conditions caused by the distance of cyclone trajectories which are quite far from the verification station area. Delft-3D simulation modeling was conducted to determine the condition of the ocean and atmospheric dynamics during the Dahlia Tropical Cyclone phase. The peak of the significant wave height reached a value of 3.24 meters at the Ciwandan Station which was caused by wind induction from the Dahlia tropical cyclone. The peak of swell height reached a value of 3.0 meters with the direction of propagation towards the Sunda Strait. Automatic weather system data shows that wind direction is mostly from the Southwest with speeds reaching 11-17 knots during Dahlia Tropical Cyclone. The study presented here proves the important rule of wind induction on swell propagation from tropical cyclones which causes maximum significant wave heights and sea level anomalies. The Delft-3D model results compare favorable with observations from the Geospatial Information Agency revealing a strong correlation of 0.86 indicating that the Delft-3D model in this case provides trustworthy predictions.