Kajian hubungan reflektifitas dan intensitas curah hujan berbasis radar cuaca di lereng merapi sebagai masukan sistem peringatan dini banjir lahar

Radar data with the best accuracy on spatial, accuracy of rainfall intensity calculation and lag time information can improve accuracy in lava flood early warning system. The objective of the study was to find radar data with the best on spatial accuracy for Z-R relation determination and identification of lag time between weather radar and rain surface (raingauge).

Extraction value and match up on weather radar and rain gauge using TMM (Traditional Matching Method) method. Determination of best accuracy PPI and CAPPI radar data both qualitatively and statisticaly with defined lag time divided into 3 filtering scenarios. Statistically use method of ME (Mean Error) and MAE (Mean Absolut Error).

Qualitatively comparison result radar data CAPPI 1 km as the best accuracy on spasial. Statistically, radar data PPI 0.5° is the lowest error rate. Qualitatively comparison, optimal Z-R relation results is obtained in the 2nd filtering scenario whereas statisticaly comparison optimal Z-R relation result using MAE statitistic method in the 2nd filtering scenario. All Z-R relation equations are still doubtful because the value of a coefficient is too high. The indicator that the comparison is optimal is based on the value of coefficient of determination (R2) consistency. The result of cross-correlation for identification of lag time T0 (0-5 minutes) is the most optimal correlation. Spatial accuracy comparison results, implementation of radar data as inputs an early warning system dynamically to make the system more accurate.