| dc.description.abstract | In February 2019, Wutip was formed and rapidly intensified into a super typhoon in the Western North Pacific, causing the loss of property for the Federated States of Micronesia. The evolution of Wutip case made a huge question for the typhoon forecaster since there were strong negative sea surface height features (roughly -8.5 cm) on their trajectory. Using a series of data such as JTWC’s best-track data, HYCOM, SODA, and ERA5, this study aims to investigate the impact of multiple factors (e.g., the large-scale oceanic environment, the large-scale atmospheric environment, and typhoon characteristics) on Wutip’s intensity. In the first scenario, the Wutip’s size compared to the climatological intensifying typhoons within 14 years (2005 – 2018) in both the annual average and the winter seasons. The result indicated that the typhoon size was not a booster factor for Wutip intensification. The sensitivity experiment from the Price 2009 model showed that a size enlargement of Wutip about 10% – 20% compared to climatology triggered an increase in the TC-induced cooling effect in a range of 15% to 30%. The second scenario was compared with typical tropical storms in January. The result showed that the cooler pre-upper-thermal structure profiles induced a great self-cooling effect over 2.5oC. Thus, this was the reason why historical typhoons of January could not intensify into super typhoons with cooler ocean profiles. Thirdly, the evolution in the southeast quadrant region had a significant contributor to the intensification process of super typhoons in February, especially for Wutip. It is noteworthy that Wutip was unable to break the historical records unless it was formed or intensified in the southeast quadrant region. The moderate vertical wind shear around 7-8 m/s was a favorable and controlling factor for historical super typhoons (STYs) compared to non-super typhoons (non-STYs) in January and February. Contrastingly, the dry air of relative humidity at mid-level just slowed down the intensification process for both STYs and non-STYs. In conclusion, this study emphasizes the crucial role of the thickness of warm climatological background in the Western North Pacific, the geographical location where Wutip formed and rapidly intensified, and the supporting factor from atmospheric conditions during the Wutip intensification process. | en_US |