QUANTITATIVE PRECIPITATION ESTIMATION (QPE) BASED ON RADAR DATA WITH Q-MATCHING CORRECTION IN EAST JAVA

• Main Author: Chavez Assad Patriot, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/65194
• Institution: Institut Teknologi Bandung

Precipitation is any liquid or frozen water that forms in the atmosphere and falls back to the Earth’s surface. One of precipitation measurements is using a surface weather radar that measurement result is in the form of radar reflectivity and converted to precipitation intensity using Z-R or QPE radar relationship. The relationship that is commonly used are Marshall-Palmer and Rosenfeld, but cannot be applied directly due to location factors and variations in raindrop size. In Indonesia, development of Z-R has been carried out in Surabaya where the evalution is still not accurate and the relationship only applied to that area. In addition, QPE radar result can be biased so that a correction method is needed, where one of the method is Q-Matching. In this study, a new QPE radar is developed and used Q-Matching correction with comparing the accuracy between QPE radar result before and after correction in East Java. This study uses C-band weather radar data and 20 observation stations in East Java which are selected in advance by spatial, time availability, and completeness of data. The data period is December 2018-February 2019, where December 2018- January 2019 are training period for building linear regression model and matching distribution functions. Meanwhile February 2019 is used as testing period for evaluation QPE radar using correlation, RMSE, POD, FAR and comparison of CDF. The data is averaged per hour before used. The results showed that Z-R relationship in East Java during training period is Z = 158,36R1,41. Then in testing period, 5 pairs of distribution functions are used and it is found that Gamma distribution function generate the best increasing correlation and decreasing RMSE with values of 5,29% and 85,19% respectively and CDF of QPE radar is relatively close to the CDF of observed rainfall for correction using Q-Matching. The prediction results for very light, light, and heavy rain are relatively better in corrected QPE based on POD and FAR score, although there are a decrease in POD score for very light rain event and an increase in FAR score for heavy rain event.