Basconcillo Joseph, Moon Il-Ju
Typhoon Research Center, Jeju National University, Jeju, South Korea.
Department of Science and Technology, Philippine Atmospheric, Geophysical, and Astronomical Services Administration, Quezon City, Philippines.
Sci Rep. 2021 Apr 1;11(1):7416. doi: 10.1038/s41598-021-86814-x.
To imply the gravity of their impact on Christmas celebration, the term Christmas typhoon recently became more popular to refer to tropical cyclones (TC) in the Western North Pacific (WNP) during its less active season. The past 9 years from 2012 to 2020 saw more than 70% (210%) increases in Christmas typhoon occurrences in the WNP (Philippines). Furthermore, Mindanao Island, which is located in southern Philippines, has experienced an unprecedented 480% increase in TC passage in the same period. Here we show that the detected recent increase in Christmas typhoons are mainly associated with the shift of the Pacific Decadal Oscillation to its positive phase in early 2010s, which led to favorable changes in the large-scale environment for TC development such as higher relative vorticity, anomalous low-level westerlies, warmer sea surface temperatures in the central Pacific, and extended WNP subtropical high. We also found that the poleward shift of the Intertropical Convergence Zone and possibly, the recent recovery of the Siberian High contributed to such increased occurrences. As opposed to the more active TC season, there is a wide research gap during the less active season. We aim to fill in this knowledge gap to gain better insights on TC risk reduction.
为了暗示它们对圣诞节庆祝活动影响的严重性，“圣诞台风”一词最近在指西太平洋（WNP）活动较少季节的热带气旋（TC）时变得更加流行。从2012年到2020年的过去9年里，西太平洋（菲律宾）的圣诞台风发生次数增加了70%以上（210%）。此外，位于菲律宾南部的棉兰老岛在同一时期经历了热带气旋过境次数前所未有的480%的增长。我们在此表明，最近检测到的圣诞台风增加主要与21世纪10年代初太平洋年代际振荡向正相位的转变有关，这导致了有利于热带气旋发展的大尺度环境变化，如相对涡度增加、异常低空西风、中太平洋海表温度升高以及西太平洋副热带高压范围扩大。我们还发现热带辐合带的向北移动以及西伯利亚高压最近可能的恢复也促成了此类事件的增加。与热带气旋活动较多的季节相反，在活动较少的季节存在广泛的研究空白。我们旨在填补这一知识空白，以便更好地了解热带气旋风险降低情况。
