PREDICTION OF AUSTRALIAN SUMMER MONSOON (ASM) MONSOON AND THE BEGINNING OF RAINFALL (BRS) IN JAVA ISLAND BY USING CLIMATE FORECAST SYSTEM (CFS) VERSION 2 OUTPUT

• Main Author: Rafi Al Hariri Nst, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69907
• Institution: Institut Teknologi Bandung

Monsoon is an annual cycle that distinguishes the condition of dry and wet atmosphere. In Indonesia, there are two kind of global monsoon such as Asia Summer Monsoon (ASM) and Australia Summer Monsoon (AuSM) which is causing wet and dry season. Predicting the beginning of wet seasons and onset monsun monsoon is important due to its affect to lots of aspect of life such as Agriculture. Java Island, as an area which is consistently influenced by monsoon, has been being the economic center of Indonesia. These are the reasons why predicting onset monsun monsoon and the beginning of rain seasons is important in Java island. As a seasonal forecast model, Climate Forecast System (CFS) has been coupled between its atmosphere, ocean, and contingental distribution. However, CFS’s output relatifly coarse need to be downscaled, to improve its output and reduce its bias. By using Spatial Disaggregation Bias-Correction, the bias of rainfall has been reduced proved by its positive Brier Skill Score (BSS) relative with CFS raw data. Based on the beginning of rain season definition, the results indicate, there is slightly difference between the CFS-corr and CFS-raw outputs. As it is shown by its Brier Score values, which is indicating that CFS-corr and CFS-raw have lowaccuracy for predicting the beginning of rain seasons. However, for defining the onset of monsoon, CFS has a fairly good accuracy based on its BS value that is close to 0. Thus, by evaluating the prediction of the onset monsoon and the beginning of rain season relative with the TRMM data output, CFS can be used operationally to predict the delay of onset monsoonand the beginning of rainfall with BMKG old criteria.