@article{39c35fa15fea4e7ba45a4fa8e4cc0d63,
title = "Investigating the abrupt change of tropical cyclone (TC) activity in the Western North Pacific by using different TC genesis indices",
abstract = "The tropical cyclone (TC) genesis indices are used to investigate the abrupt change of TC genesis frequency (TCGF) in the Western North Pacific (WNP) from 1979 to 2014 and to discuss the factors leading to the abrupt change. This study shows that TCGF had an abrupt decrease in 1997, but the popular TC genesis indices used in recent studies do not reflect this feature. An appropriate TC genesis index must consider both thermal and dynamic effects to reflect the TCGF abrupt change in the WNP. We modify the dynamic and thermal effects of the existing indices and propose a new TC genesis index, MoχGPI, which is consistent with the observational abrupt change of TC activity regardless of spatial distribution or time-series patterns. A budget analysis of MoχGPI is conducted to discuss the individual contribution of large-scale environmental parameters to the TCGF abrupt change. The results show that the change in relative vorticity (including contributions not only from the environmental relative vorticity, but also a part from the relative vorticity by TCs themself) is the dominant effect leading to the TCGF abrupt change in 1997, followed by the vertical wind shear effect.",
keywords = "abrupt change, tropical cyclone genesis frequency, Western North Pacific",
author = "Hsiao, {Li Peng} and Tsou, {Chih Hua} and Yu, {Jia Yuh}",
note = "Funding Information: This study was sponsored by the Ministry of Science and Technology (MOST) in Taiwan under Grants MOST105‐2111‐M‐008‐025‐MY3 and MOST106‐2111‐M‐008‐002‐MY2. The first author was also sponsored by the MOST postdoc fellowship under Grant MOST107‐2811‐M‐008‐2549. The ERA‐interim data were downloaded from the Climate Data Guide under UCAR (University Corporation for Atmospheric Research) at https://climatedataguide.ucar.edu/climate-data and the TC best‐track data were downloaded from the NOAA (National Oceanic and Atmospheric Administration) website at http://www.ncdc.noaa.gov/ibtracs . The authors thank the two anonymous reviewers for their helpful comments and suggestions to improve the quality of this article. Funding Information: This study was sponsored by the Ministry of Science and Technology (MOST) in Taiwan under Grants MOST105-2111-M-008-025-MY3 and MOST106-2111-M-008-002-MY2. The first author was also sponsored by the MOST postdoc fellowship under Grant MOST107-2811-M-008-2549. The ERA-interim data were downloaded from the Climate Data Guide under UCAR (University Corporation for Atmospheric Research) at https://climatedataguide.ucar.edu/climate-data and the TC best-track data were downloaded from the NOAA (National Oceanic and Atmospheric Administration) website at http://www.ncdc.noaa.gov/ibtracs. The authors thank the two anonymous reviewers for their helpful comments and suggestions to improve the quality of this article. Publisher Copyright: {\textcopyright} 2020 Royal Meteorological Society",
year = "2020",
month = nov,
day = "30",
doi = "10.1002/joc.6558",
language = "English",
volume = "40",
pages = "5959--5972",
journal = "International Journal of Climatology",
issn = "0899-8418",
publisher = "John Wiley and Sons Ltd",
number = "14",
}