Impact of the Boreal Summer Intraseasonal Oscillation on Typhoon Tracks in the Western North Pacific and the Prediction Skill of the ECMWF Model

Abstract

The tropical intraseasonal oscillation (ISO) strongly influences tropical cyclone (TC) genesis. However, little is known concerning its impact on TC tracks. Here, we examine how TC tracks in the western North Pacific are modulated by the boreal summer ISO (BSISO) during each month of the TC season (June–October) using the best track data and how well the modulation are reproduced in the European Centre for Medium-Range Weather Forecasts (ECMWF) model forecasts. The results reveal that the impact of the BSISO on the typhoon tracks varies month to month. The ECMWF model successfully reproduces this impact up to a month in advance. A simple advection model shows that the reproduction of the modulations in the TC genesis location leads to accurate TC track forecasts. These results suggest that the BSISO is one of the major sources of TC track predictability at the subseasonal time scale (2 weeks to 2 months).