Observed decadal shifts and trends in global tropical cyclone activities from 1980 to 2021

This study investigates the variability of annual tropical cyclone (TC) frequency and intensity over six major ocean basins from 1980 to 2021. Statistical change-point and trend analyses were performed on the TC time series to detect significant decadal variation in TC activities. In the middle of the last decade of the 20th century, the frequency of TC genesis in the North Atlantic basin (NA) and North Indian Ocean (NIO) increased dramatically. In contrast, the frequency in the western North Pacific (WNP) decreased significantly at the end of the century. The other three basins—the East Pacific, southern Indian, and South Pacific—all experienced a declining trend in annual TC frequency. Over recent decades, the average TC intensity has decreased in the East Pacific and the NA, whereas it has risen in the other ocean basins. Specifically, from 2013 to 2021, the average peak TC intensity in the NIO has enhanced significantly. The magnitude of the Genesis Potential Index exhibits fluctuation that is consistent with large-scale parameters in the NIO, NA, and WNP, emphasizing the enhancing and declining trends in TCs. In addition, a trend and correlation analysis of the averaged large-scale characteristics with TCs revealed significant associations between the vertical wind shear and TC frequency over the NIO, NA, and WNP. Therefore, global TC trends and decadal variations associated with environmental parameters deserve further investigation in the future, mainly linked to the significant climate modes.

© 2022 The Authors.

研究發現在1980–2021期間全球6個海域每年熱帶氣旋的發生頻次和強度具有顯著年代際變化規律, 最近幾十年, 北大西洋和北印度洋的熱帶氣旋發生頻次明顯增加, 但西北太平洋的熱帶氣旋卻顯著下降. 另外三個海域, 東太平洋, 南印度洋和南太平洋發現所生成的熱帶氣旋有減少趨勢. 但在過去十幾年, 平均熱帶氣旋的強度除了在東太平洋和北大西洋有所減弱但在其他幾個海域有所加強, 特別是在 2013–2021期間, 北印度洋的平均熱帶氣旋的強度增強明顯. 熱帶氣旋的潛在生成指數 (GPI) 增加或減少趨勢變化與北印度洋, 北大西洋和西太平洋熱帶氣旋變化相關的大尺度環流一致. 另外, 北印度洋, 北大西洋和西太平洋上空的垂直風切變是影響其區域熱帶氣旋發生頻次變化的主要因數, 不同的氣候模態也可能對全球熱帶氣旋的趨勢變化和年代際變化有影響, 值得進一步研究.