Recent increase in the occurrences of Christmas typhoons in the Western North Pacific

Abstract

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.

Variability of tropical cyclone rainfall volume in the Philippines

“…While 34 years have negative anomalies in which 12 (1958, 1961, 1965, 1969, 1975, 1992, 1997, 2002, 2005, 2007, 2010, 2018) of the 34 years exceeded 1 SD . TCs in the WNP have been shown to be influenced by the PDO (Wang et al ., 2010; Aiyyer and Thorncroft, 2011; Basconcillo and Moon, 2021); however, its influence on TC‐induced rainfall volume in the Philippines is limited. PDO index has a marginally significant weak negative correlation with annual TC rainfall r = −0.23 ( p = .06).…”

“…This increasing trend was attributed to changes in environmental steering, particularly the strengthening of the WNP subtropical high. Recently, Basconcillo and Moon (2021) elucidated the role of the WNP subtropical high, as well as the shifting of the PDO phase and the Inter‐Tropical Convergence Zone (ITCZ) position, in the increased late‐season TC landfalls in the Philippines which explains the 2002–2015 trend.…”

A Contrast of Recent Changing Tendencies in Genesis Productivity of Tropical Cloud Clusters over the Western North Pacific in May and October

“…On the contrary, increased WNP TC genesis frequency could be observed in May after the late 1990s [12,13]. Other studies [15][16][17][18][19][20] also support that the interdecadal variations and recent changes in WNP TC activity are obviously seasonally dependent, suggesting possible different influential processes responsible for TC activity changes in different seasons.…”

Comparison of sustainable flood risk management by four countries – the United Kingdom, the Netherlands, the United States, and Japan – and the implications for Asian coastal megacities

“…Climate change is raising sea levels, making storm surges more hazardous , and is increasing the fre-quency, intensity, and magnitude of storms (typhoons), intense rainfall events, and sea surges (Basconcillo and Moon, 2021;Chan et al, 2021Chan et al, , 2022Ku et al, 2019;Webster, 2008;Webster et al, 2005). Natural resource extraction is also increasing flood hazard through the land subsidence it causes; for example, in the coastal area of Bangkok groundwater extraction has resulted in subsidence of 2 m since 1970 (Syvitski et al, 2009).…”