Pemodelan Curah Hujan Kumulatif Mingguan dari Data Curah\ud Hujan Stasiun Purajaya.

The goal of this research is to study the periodic and stochastic models of data series of the weekly\ud cumulative rainfall. The study was done by using daily rainfall series with long data 25 years\ud (1977-2001) of Purajaya station. Based on the daily rainfall series, a weekly cumulative rainfall\ud series was calculated. The series of rainfall is assumed to be free of trend. Periodicities of\ud periodic rainfall model of the weekly rainfall data series were presented by using 509 periodic\ud components. Stochastic components of the weekly rainfall data are assumed as residues between\ud the rainfall data with the periodic rainfall model. The stochastic components were calculated\ud using the approach of autoregressive model. Stochastic Model presented in this research is using\ud the thirth order autoregressive model. Validation between rainfall data and the periodic-\ud stochastic rainfall model is done by calculating the correlation coefficient. For this study, the\ud correlation coefficient between the data and the model of the weekly cumulative rainfall is 0,9999.\ud From the results of this study can be inferred that the model of the weekly rainfall from Purajaya\ud station gives very highly accurate approach.\ud Keywords : weekly cumulative rainfall, periodic-stochastic, FFT, autoregressive model