The impact of Typhoon Jangmi (2008) on the midlatitude flow. Part I: Upper-level ridgebuilding and modification of the jet

Abstract

This study identifies the key physical process that governs the direct impact of the extratropical transition (ET) of Typhoon Jangmi on the midlatitude flow in September 2008. Jangmi was the strongest tropical cyclone (TC) in the western North Pacific in 2008 and occurred during the THORPEX Pacific Asian Regional Campaign (T-PARC). A distinct outflow–jet interaction resulted in ridgebuilding directly downstream of the ET system and a strongly accelerated upper-level jet streak over Japan. A combination of model and observational data is used to investigate the interaction of the transforming TC with the midlatitude flow and a potential vorticity (PV) surgery technique based on PV inversion is developed to further quantify the contribution of the TC to the modification of the midlatitude flow during ET.