THE INFLUENCE OF C-BAND WEATHER RADAR DATA ASSIMILATION IN NUMERICAL WEATHER PREDICTION OF HEAVY RAIN EVENTS IN NORTH SUMATRA FOR THE 2020 PERIOD

• Main Author: Angela Putri M., Tesalonika
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/83197
• Institution: Institut Teknologi Bandung

The topography of North Sumatra leads to high convective activity, making accurate weather prediction crucial for disaster risk mitigation. However, weather prediction in North Sumatra faces challenges due to high atmospheric variability. Continuous improvement in weather prediction is essential, and one approach is combining observational data with previous short-term prediction results. Enhancing regional models by assimilating radar reflectivity and radial velocity can improve initial conditions for moisture and wind speed, which potentially affects convective cloud formation and rainfall, thereby improving model outputs. This study utilizes the regional numerical weather prediction model Weather Research and Forecasting Data Assimilation (WRFDA) with the 3DVar method, comparing the time window lengths of three different models. The assimilated data include reflectivity and radial velocity from the C-Band Weather Radar owned by BMKG Medan. Prediction results with assimilation are compared to those without assimilation. The study results show that radar data assimilation improves the mean prediction error, which initially was -0.934 in the model without assimilation, to -0.834 in the experimental model with a 1-hour time window (DA1), -0.914 in the experimental model with a 3-hour time window (DA2), and -0.67 in the experimental model with a 9-hour time window (DA3). Additionally, the study indicates variations in temporal lag, with longer time window models generally exhibiting smaller prediction lag times. Overall, the research demonstrates that assimilating reflectivity and radial velocity data with longer time windows yields more accurate predictions in terms of both timing and intensity