Generalized linear models (GLMs) approach in modeling rainfall data over Johor area

Observations of rainfall data are always changing over time. With the concern over climate change, this study is done to demonstrate how Generalized Linear Models (GLMs) could be utilized to model daily rainfall amount over Johor area. Hence, in modeling rainfall amount, Fourier series are used as the smoothing technique. This research concentrated on the daily rainfall series with the duration period of 1980 to 2011 from six rainfall stations in Johor area. The results indicated that the rainfall stations demonstrate different behaviours of rainfall patterns. Both stations that are located at the eastern area of Johor which is Mersing and Hospital Kota Tinggi are best described with four and three harmonics, while one harmonic is sufficient to model the mean rainfall per rainy day at the stations that are located at the west of Johor. Based on the resulting curves with fitted smoothing parameters, a good summary of statistics of the six stations were obtained. The results from the model will then be used to compare the rainfall patterns among the stations.