OJS> Vol.4 No.9, October 2014

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Sitti Sahriman, Anik Djuraidah, Aji Hamim Wigena

Department of Statistics, Bogor Agricultural University, Bogor, Indonesia.

Statistical downscaling (SD) analyzes relationship between local-scale response and global-scale predictors. The SD model can be used to forecast rainfall (local-scale) using global-scale precipitation from global circulation model output (GCM). The objectives of this research were to determine the time lag of GCM data and build SD model using PCR method with time lag of the GCM precipitation data. The observations of rainfall data in Indramayu were taken from 1979 to 2007 showing similar patterns with GCM data on 1^st grid to 64^th grid after time shift (time lag). The time lag was determined using the cross-correlation function. However, GCM data of 64 grids showed multicollinearity problem. This problem was solved by principal component regression (PCR), but the PCR model resulted heterogeneous errors. PCR model was modified to overcome the errors with adding dummy variables to the model. Dummy variables were determined based on partial least squares regression (PLSR). The PCR model with dummy variables improved the rainfall prediction. The SD model with lag-GCM predictors was also better than SD model without lag-GCM.

Cross Correlation Function, Global Circulation Model, Partial Least Square Regression, Principal Component Regression, Statistical Downscaling

Sahriman, S. , Djuraidah, A. and Wigena, A. (2014) Application of Principal Component Regression with Dummy Variable in Statistical Downscaling to Forecast Rainfall. Open Journal of Statistics, 4, 678-686. doi: 10.4236/ojs.2014.49063.