Multimodel ensemble forecasting of rainfall over East Asia: regularized regression approach

Abstract

This paper considers the problem of predicting the rainfall over East Asia from multimode outputs. For this purpose, we propose a new multimode ensemble method based on regularized regression approach, which consists of two steps, the pre-processing step and the ensemble step. In the pre-processing step, we improve prediction from each model output using regularized regression, and in the ensemble step, we apply regularization-based regression method to combine the result from the pre-processing step. The main benefits of the proposed method are that it improves prediction accuracy, and it is capable of solving the singularity problem so that it can integrate many climate variables from multimode outputs for a better prediction. The proposed method is applied to monthly outputs from nine general circulation models (GCMs) on boreal summer (June, July, and August) over 20 years (1983-2002). The prediction ability of the proposed ensemble forecast is compared with the observations and the outputs (prediction) from each GCM. The results show that the proposed method is capable of improving forecast accuracy by adjusting each model before combining.