APLIKASI FAST FOURIER TRANSFORM DALAM ANALISIS KORELASI PERIODISITAS CURAH HUJAN DI SUMATERA UTARA DENGAN FENOMENA VARIABILITAS IKLIM GLOBAL

Abstract

North Sumatra Province has rainfall variability and patterns that are influenced by various global climate variability phenomena such as Dipole Mode, IOD (Indian Ocean Dipole), Madden Julian Oscillation (MJO) and ENSO (El Niño-Southern Oscillation). To see the activity and influence of each of these global climate phenomena, several indices are used, Dipole Mode Index (DMI) for IOD, Australian Monsoon Index (AUSMI) and Western North Pacific Monsoon Index (WNPMI) for Monsoon Circulation, and NINO 3.4 Index for ENSO phenomenon. This research uses monthly rainfall data for 30 years which will be spectrally analysed with FFT (Fast Fourier Transform), then correlate and analyse the periodicity pattern of rainfall to the global climate phenomenon index through Pearson Correlation. FFT spectral analysis of Rainfall and Global Climate Phenomena Index in North Sumatra reveals variations in periodicity patterns. The region shows differences in rainfall recurrence patterns, with the most periodic peaks at 12 Months (7 rainfall stations). For 12 Months there are at North Sumatra Climatology Station, Belawan Maritime Meteorological Station, and Kualanamu Meteorological Station, Deli Serdang Geophysical Station, Aek Gondang Meteorological Station, FL Tobing Meteorological Station, and Binaka Meteorological Station. The strongest correlation between Rainfall and Climate Index is DMI (Dipole Mode Index) and NINO 3.4 Index. DMI has the strongest correlation at Kualanamu Meteorological Station, Aek Godang Meteorological Station, FL Tobing Meteorological Station. For the NINO Index 3.4, the strongest correlation is at Bawean Maritime, Kualanamu Meteorological and Aek Gondang Meteorological Stations.