JpGU-AGU Joint Meeting 2017

講演情報

[EE] ポスター発表

セッション記号 A (大気水圏科学) » A-AS 大気科学・気象学・大気環境

[A-AS06] [EE] 台風研究の新展開~過去・現在・未来

2017年5月20日(土) 10:45 〜 12:15 ポスター会場 (国際展示場 7ホール)

コンビーナ:中野 満寿男(海洋研究開発機構)、和田 章義(気象研究所台風研究部)、金田 幸恵(名古屋大学宇宙地球環境研究所)、伊藤 耕介(琉球大学)

[AAS06-P12] Unusual growth in intense typhoon occurrences over the Philippine Sea in September after the mid-2000s

*Jing Yang1 (1.Beijing Normal University)

キーワード:tropical cyclone, decadal change

During the global warming hiatus period (1998–

present), a pronounced increase in the number of intense

typhoon occurrences was identified over the Philippine

Sea (PS: 5°–25°N, 125°–140°E) in September after the

mid-2000s. Comparing two periods before and after the

mid-2000s indicates that intense typhoons rarely occurred

over the PS in September before the mid-2000s, with a frequency

of fewer than 0.4 per year, but reached up to nearly

1.5 per year after the mid-2000s. The abrupt increase in

intense typhoon occurrences over the PS was primarily

attributed to increased tropical cyclone (TC) genesis and

favorable large-scale conditions for TC intensification. The

increase in TC genesis number over the PS was caused

by contributory dynamical conditions, including positive

low-level relative vorticity anomalies and anomalous

ascents, which corresponded to a southwestward shift and

strengthening of the monsoon trough. In addition, among

the favorable large-scale conditions, the increased relative

humidity that resulted from intensified moisture flux

convergence exerted essential effect on the TC intensification.

These changes in atmospheric environmental conditions

favoring intense typhoon occurrences over the PS

were primarily associated with the change in the tropical

Indo-Pacific sea surface temperature (SST) around the mid-

2000s. Besides that, the positive feedback TCs exerted on

the circulation was also conducive to the unusual growth in

intense typhoon occurrences over the PS. And note that the

role of SST anomalies in the air–sea interaction is the key

to interpret why the unique phenomenon only occurred in

September