Influence of the Kuroshio Large Meander on the intensity of a distant tropical cyclone: A case study of Typhoon Neoguri (2019)

To examine how the Kuroshio large meander (KLM) changes the intensity of a distant tropical cyclone (TC), we conducted a control simulation of Typhoon Neoguri, which approached the Kuroshio during the KLM event in October 2019, and sea surface temperature (SST) sensitivity experiments regarding the SST warming near the Tokai District and SST cooling south of the Kii Peninsula (KP) during KLM periods. Comparisons between the control and SST sensitivity runs revealed that the KLM can impact the intensity of Neoguri, even being far away from the Kuroshio. KLM-induced SST warming (cooling) enhanced (weakened) the moisture influx toward Neoguri through changes in the surface evaporation in the KP–Tokai area, indicating the penetration of wetter (drier) air parcels into the TC inner core region. The relatively wet (dry) environment in the inner core modulated the latent heating around the TC center, leading to enhancing (weakening) the distant TC. In October 2019, the KLM acted in the direction of strengthening Neoguri because the warm (cool) SST anomalies near Tokai (KP) were remarkable (insignificant). This study suggests that the KLM could have contradictory impacts on the intensity of a distant TC, depending on the KLM-induced SST anomaly patterns in the KP–Tokai area.