MODIFIKASI KONSTANTA PERSAMAAN Z-R RADAR SURABAYA UNTUK PENINGKATAN AKURASI ESTIMASI CURAH HUJAN
DOI:
https://doi.org/10.31172/jmg.v21i2.545Keywords:
Hubungan Z-R, Estimasi curah hujan, Radar cuacaAbstract
Radar cuaca sangat berpotensi untuk memberikan estimasi curah hujan beresolusi tinggi secara spasial dan temporal yang dapat meningkatkan akurasi prakiraan dini cuaca ekstrim dan juga dapat menyediakan informasi curah hujan pada wilayah yang tidak mempunyai stasiun pengamatan curah hujan. Radar cuaca tidak dapat secara langsung mengukur intensitas curah hujan, melainkan berdasarkan hubungan empiris antara reflektifitas radar (Z) dan tingkat curah hujan (R) dalam hubungan Z-R (Z = ARb). Pada penelitian ini, metode optimalisasi digunakan untuk menentukan konstanta A dan b yang sesuai untuk wilayah Surabaya di provinsi Jawa Timur. Data reflektifitas pada radar Surabaya dan data curah hujan per jam dari stasiun Juanda Surabaya pada periode Desember 2014 - Februari 2015 digunakan dalam studi ini. Hasil studi menunjukkan bahwa hubungan Z-R dengan persamaan Z = 110R1,6 menghasilkan estimasi curah hujan yang memiliki indikator statistik lebih baik dibandingkan dengan estimasi dari persamaan Marshall-Palmer (MP, Z = 200R1,6) dan Rosenfeld (Ros, Z = 250R1,2) sehingga dapat meningkatkan akurasiestimasi curah hujan di wilayah Surabaya.
Weather radar can potentially provide rainfall estimates with high spatial and temporal resolution in which improving the early warning accuracy of extreme weather and also provide rainfall estimates in areas with insufficient rainfall stations. Weather radar cannot directly be used to measure the rainfall intensity, but based on an empirical relationship between the reflectivity (Z) and rainfall rate (R) in the Z-R relationship (Z = ARb). In this study, an optimization method was used to determine suitable constants A and b for Surabaya, East Java province. The reflectivity data from Surabaya radar and hourly rainfall data at Juanda station in Surabaya during a period of December 2014 - February 2015 were used in this study. The results show that a Z-R relationship in the form of equation Z = 110R1,6 produces rainfall estimates with a better statistical indicator than ones produced by Marshall-Palmer (MP, Z = 200R1,6) and Rosenfeld (Ros, Z = 250R1,2) relationships, making it suitable for improving the accuracy of rainfall estimates for Surabaya.
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