The Current System for Monitoring and Prediction of El Nino in JMA and Impact of Salinity data Assimilation in the Equatorial Western Pacific on El Nino Prediction

摘要

ENSO is one of the most distinct phenomena which can affect world climate. The Japanese climate is also connected closely with ENSO. JMA monitors and predicts El Nino and La Nina to support seasonal forecasting for Japan area. In order to carry out these tasks, JMA is operating an Ocean Data Assimilation System (ODAS) (Kimoto et al., 1997) and an El Nino prediction model (a coupled ocean-atmosphere model). First, the current system for monitoring and prediction of El Nino in JMA is introduced. During the past few years, TAO buoys west of 156° E have been replaced by TRITON buoys which are deployed by JAMSTEC (Japan Marine Science and Technology Center). It is noteworthy that the TRITON buoys are equipped with sensors to measure salinity at several depths. As they are located in the western tropical Pacific, their observations are valuable for monitoring the warm pool. With the salinity observations, it is also expected that the accuracy of Hl Nino prediction is increased. To understand the importance of the salinity observations by the TRITON buoys, impact of the salinity data assimilation on El Nino prediction was investigated (Ishii et al., 2001). As an example of efforts to develop a new system for El Nino monitoring and prediction, some results of this investigation are given here.