Yopi Ilhamsyah

Study of current circulation in the Northern Waters of Aceh

The northern waters of Aceh are directly adjacent to the Malacca Strait, the Andaman Sea, and the Indian Ocean. These waters are an important route in the activities of shipping, fishing and others. The study of current circulation was studied by using the 2D hydrodynamic models. The purpose of this study is to determine the current patterns during the Northeast (February 2016) and southwest (August 2016) monsoons. To generate the models, we use the wind force obtained from European Center for Medium-Range Weather Forecast (ECMWF) 2016. The results show that the current circulation generally follows the bathymetry pattern and monsoonal direction.

The beach slopes and grain size distribution at Anoi Itam and Pasir Putih Beaches, Sabang City

Since ocean and land greatly influence on coastal processes, and continually affected by these dynamics, the coastal zone become the most dynamical region of the ocean. Coastal geomorphological changes principally in a more specific of beach processes and made of are found from the characteristics of the sediments over certain coastal waters. This research examines the relationship between beach slope and mean grain size. The objective of the research is to explain the mechanisms of sediment distribution associated with different beach slopes. The sampling locations were situated at Anoi Itam and Pasir Putih Beaches of Sabang City on October 2016 and April 2017. Coring method was used in this research. There were six collection sites with two repetitions of treatment in each location. The distribution of sediment based on grain size was measured using wet sieving procedure extracted by stratified sieving. The results showed that medium sand are dominant at Anoi Itam and Pasir Putih Beaches while beach slopes vary from nearly flat to gently sloping.

Simulation of surface heat fluxes of Typhoon Songda (Chedeng) 2011 using WRF-ARW model

Heat fluxes particularly latent heat is important to drive the development, formation, and intensification of Typhoon Songda (Chedeng). The research was carried out by performing WRF ARW. Three domains with finest resolution at 3.2-km in domain three were utilized in the model. The model involved significant physics parameters, e.g., Kain-Fritsch in the cumulus scheme, Yonsei university in the PBL scheme, and WRF Single-Moment 3-class in the microphysics scheme . The analysis focused on May 26th upon mature stage of Songda (Chedeng). The result showed that the simulation of the eye, three-dimensional structure of internal wind flow, and surface heat fluxes were well-performed. The intensity of Songda (Chedeng) was represented by azimuthal velocity. It showed that the maximum wind was 72 ms-1 occurred at the eye wall at critical radius of 20-km from the eye center where large portion of latent heat available in the area. Significant variation of surface sensible and latent heat fluxes were occurred between the inner and outer core. Thus, it affected to develop a strong horizontal temperature gradient which further intensify the cyclonic inward penetration into the inner core. In terms of disaster risk reduction, this study bring benefit to assist operational weather forecaster to produce good short-range forecasts of the Typhoon intensities. If the surface heat fluxes increase gradually, early warning system on typhoon intensities that will affect over particular region is then released.