16:30 〜 16:45
[AAS06-09] Analysis of Tropical Cyclone Rapid Intensification in the Southwest Pacific Region
キーワード：台風、急発達
This study statistically investigates the characteristics of tropical cyclones (TCs) undergoing rapid intensification (RI) in the Southwest Pacific (SWP) region in the 37 years from 1986 to 2022. Among 364 TCs, 82 rapidly intensifying TCs (RI-TCs) are detected using the definition wind speed increase of 30 kt (15.4 ) or more in a 24-h period. RI-TCs preferentially occurred during the southern hemisphere (SH) summer season, that is, tropical cyclone season. Analysis of long-term trends shows an increasing trend in RI-TC occurrence over the 37-year period at the 95% confidence level based on two tailed t-test. In El Niño years, TCs tend to undergo RI more frequently presumably due to the average location of warm sea surface temperatures to the further east and central pacific. In contrast RI-TCs occurred less frequently during La Niña years. The rates of RI-TC occurrence increased from 1990s to 2020s. The RI onset time is usually 0 – 42 h after TC genesis time, while the frequency was maximized at 0–6 h. The most frequent duration (27% of the total) was the 24 -h duration, followed by the 30-h duration (19%), 36-h and 42-h with (18% each). Whereas the number of RI decreased as the number of RI duration increased. It is interesting to note that although there was no RI-TC with an RI duration after 84-h, one event attained RI duration of more than 120-h. RI frequently observed over the zonally elongated area around coral sea, south of Solomon Islands (Solomon Sea), Vanuatu, Fiji and Samoa. However, RI was observed rare to occur in areas of Tasman Sea, Tonga, northern waters of New Zealand, Cook Islands, and French Polynesia.