Extreme cooling of 12.5 °C triggered by Typhoon Fungwong (2008). (April 2023)

• Record Type: Journal Article
• Authors: Zheng, Zhe-Wen; Lin, Jia-Yi; Gopalakrishnan, Ganesh; Chen, Yi-Rui; Doong, Doon-Jing; Ho, Chung-Ru; Zheng, Quanan; Wu, Chau-Ron; Huang, Chen-Fen
• Is Part Of: Ocean modelling. Volume 182(2023)
• Publication Date: 2023-04
• Subjects: Typhoons -- Kuroshio intrusion -- Sea surface temperature -- Moored buoy -- Numerical modeling -- Float trajectory; Oceanography -- Periodicals; Océanographie -- Périodiques; Oceanography; Periodicals; 551.46
• DOI: 10.1016/j.ocemod.2023.102176
• Languages: English
• ISSNs: 1463-5003

Abstract

Abstract: Typhoon Fungwong, a category-2 but deadly typhoon in the 2008 Pacific typhoon season, made landfall first on Taiwan and then on Southeast China. During its approach toward Taiwan, it triggered an extreme sea surface temperature (SST) drop of 12.5 °C, which was the strongest SST drop recorded by Longdong buoy northeast of Taiwan coast from 1998 to 2017. In this study, including moored buoy temperature measurements, Argo float temperature profiles, satellite-observed SSTs, and a suite of numerical experiments performed using the Regional Ocean Modeling System were used to unveil the detailed processes of how Fungwong triggered such an extreme cooling. Subsequently, the source of the cold waters feeding the extreme cooling, possible mechanisms triggering the cooling, and consequential effects of cooling on the ambient ocean environment were systematically investigated. Results show that the extreme cooling was triggered mainly by a process of uplift of subsurface cold water tied to shore-ward Kuroshio intrusion driven by easterly/northeasterly winds and consequential entrainment mixing, while coastal upwelling driven by persistent longshore (southerly) winds plays a minor role. Nevertheless, the southerly winds still help the enhancement of entrainment mixing and thus the sea surface cooling. Finally, modeled float trajectories with temperature tracers identified where the cold water goes and indicate that the temperature drop might extend all the way toward the south end of Japan (Kyushu) along the flowing path of Kuroshio. Highlights: Typhoon Fungwong (2008) triggers an extreme sea surface cooling of 12.5 °C. It is one of the strongest cooling responses ever recorded by in-situ instruments. How Fungwong triggers such an extreme cooling was systematically resolved. Combined effect of Kuroshio intrusion and enhanced entrainment triggers it. Newly formed cold water impacts oceanic environment along Kuroshio downstream.