Modifikasi Metode Waldvogel Berdasarkan Identifikasi Karakteristik Hujan Es Yang Dikelompokkan Berdasarkan Jarak Cakupan Radar Cuaca Pada Radar Cuaca Jakarta Tahun 2010-2019

Marselinus Muaya, Amalia Khoirunnisa, Rizky Umul Nisa Fadillah, Eko Wardoyo, Fitria Puspita Sari

Abstract

Abstract: Hail detection using information from satellite and weather radar is the right choice due to spatial and temporal variability of the phenomenon of high hail. Some algorithms that use single polarization radar data have been developed for hail detection. One method that has been applied in Reflectivity-based Hail Warning or ZHAIL radar product is the Waldvogel method. This research aims to find new threshold criteria for the application of the Waldvogel method in the Jakarta weather radar observation area which is grouped into three regions based on the distance of weather radar observation. In this research, hail events from 2010 to 2019 have been analysed. Analysis of weather and weather radar data was carried out to determine the climatological characteristics of reflectivity values, reflectivit heights, and freezing levels as parameters to be used to determine the criteria for modification in the Waldvogel method. The reflectifity and reflectivity values are obtained from the processing of radar data, while the freezing level is generated from the processing of the Himawari satellite image in the infrared channel. Waldvogel's algorithm with the three modifications that have been produced, then tested using Critical Success Index, Possibility of Detection, and False Alram Ratio, calculations on the percentage value of Probability Of Hail. The results of the research is the reflectivity values, reflectivity altitude and the most accurate freezing level applied to each region that was differentiated according to the weather radar distance radius observation. Better accuracy of the application of Waldvogel method is expected to reduce therougheffects ofthehail phenomenon.

Abstrak: Metode Waldvogel merupakan metode deteksi hujan es yang mengubah reflectivity dari pengamatan radar menjadi produk Reflectivity-based Hail Warning atau ZHAIL. Penggunaan metode Waldvogel masih perlu disesuaikan dengan kondisi wilayah tropis termasuk Indonesia. Penelitian ini bertujuan untuk menemukan kriteria ambang batas baru untuk penerapan metode Waldvogel di daerah pengamatan radar cuaca Jakarta sehingga diperoleh akurasi metode Waldvogel yang lebih baik. Kriteria ambang dikelompokkan menjadi tiga wilayah berdasarkan jarak cakupan radar cuaca (wilayah I : <30 km, wilayah II : 30-100 km dan wilayah III : 100-150 km). Analisis data radar cuaca dilakukan untuk menentukan karakteristik klimatologis dari nilai reflectivity maksimum, ketinggian reflectivity maksimum, dan ketinggian freezing level sebagai parameter yang akan digunakan untuk menentukan kriteria modifikasi dalam metode Waldvogel. Verfikasi parameter diujikan dengan nilai Probability of Hail (POH), False Alarm Ratio (FAR), Possibility of Detection (POD), dan Critical Success Index (CSI). Hasil verifikasi menunjukan metode Waldvogel modiifikasi menghasilkan performa yang lebih baik dibandingkan metode Waldvogel awal untuk wilayah I dan II dengan kriteria metode Waldvogel modifikasi yang paling baik yaitu Waldvogel 3. Sedangkan untuk wilayah III, nilai kriteria yang lebih baik adalah Waldvogel tanpa modifikasi. Akurasi yang lebih baik dari penerapan metode Waldvogel diharapkan dapat mengurangi dampak buruk yang ditimbulkan dari fenomena hujan es

Keywords

Hail, metode Waldvogel, Freezing Level, radar cuaca, ZHAIL

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References

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DOI: https://doi.org/10.20961/prosidingsnfa.v4i0.35914

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