Compounding factors causing the unusual absence of tropical cyclones in the western North Pacific during August 2014

Chen, Hong; Lee, Ming-Ying; Hsu, Huang‐Hsiung; Chang, Tienyu

doi:10.1002/2016jd025507

Cited by 11 publications

(7 citation statements)

References 28 publications

(39 reference statements)

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“…In turn, the downward motion of the east–west overturning circulation anomaly may have caused an anomalous anticyclone in the WNP. The effect of CPEN–SST on the east–west overturning circulation in the North Pacific was supported by the numerical experiments (Hong et al ., ). Briefly, the CPEN–SST‐associated anomalous anticyclone in the WNP (Figure d) may have enhanced the prevailing southwesterly wind in the South China Sea, thus leading to a rainfall surplus in northern Taiwan and southern China in IP2.…”

Section: Resultsmentioning

confidence: 97%

Increasing influence of central Pacific El Niño on the inter‐decadal variation of spring rainfall in northern Taiwan and southern China since 1980

Kao

Hung

Chen

2018

Atmospheric Science Letters

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Decadal variation of spring (February–April) rainfall in northern Taiwan and southern China was significantly related to the Pacific Decadal Oscillation (PDO) during the 20th century. However, this inter‐decadal relationship subsequently weakened, and the sea surface temperature (SST) associated with the central Pacific El Niño (CPEN) has determined the inter‐decadal variation of spring rainfall in northern Taiwan and southern China since the 1980s. In this study, the effect of CPEN–SST on the inter‐decadal variation of spring rainfall in northern Taiwan and southern China was investigated. We found that a CPEN‐associated positive SST anomaly in the eastern North Pacific forced an east–west overturning circulation anomaly in the subtropical North Pacific, the descending motion of which may have generated an anticyclonic circulation anomaly in the Philippine Sea. Simultaneously, the anticyclone associated southerly winds anomaly may enhance the southwesterly in northwest of the anticyclone, which in term enhance the trough extending from Japan to northern Taiwan. The anticyclone and trough associated with the respective southwesterly and northeasterly anomalies created a convergence environment in northern Taiwan. In turn, this convergence environment contributed substantially to an inter‐decadal rainfall enhancement in northern Taiwan and southern China. Our results suggest that the effect of CPEN–SST on the inter‐decadal variation of spring rainfall in northern Taiwan and southern China has increased since 1980, especially during the transition period from the termination of a warm PDO phase to a cold phase in the late 1990s.

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Section: Resultsmentioning

confidence: 97%

Increasing influence of central Pacific El Niño on the inter‐decadal variation of spring rainfall in northern Taiwan and southern China since 1980

Kao

Hung

Chen

2018

Atmospheric Science Letters

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“…2a). This absence of TC activity in August was observed at the rst time since 1945 (Hong et al 2016).…”

Section: Introductionmentioning

confidence: 83%

“…Previous studies have indicated that the eastward propagating ISO plays an important role in the absence of TCs over the WNP in August 2014 by inducing anomalous easterlies, which led to decreased moisture and vorticity, and increased divergence (Yang et al 2015;Hong et al 2016;Bian et al 2018). The pronounced different TC genesis numbers between 1996 and 2014 suggested that the TC genesis over the WNP in August 1996 must be forced by other factors.…”

Section: Introductionmentioning

confidence: 99%

Distinct Western North Pacific Tropical Cyclogenesis During Inactive Intraseasonal Phase of August 1996 and 2014

Cao

et al. 2021

Preprint

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While intraseasonal oscillation was in the inactive phase over the western North Pacific (WNP) during August of 1996 and 2014, no tropical cyclone (TC) genesis occurred in August of 2014, whereas 9 TCs (average 5.7 TCs) formed in August of 1996 with 5 TCs in the northeastern part (the largest number since 1979) and 4 TCs in the southwestern part. The present analysis reveals an obvious southwest-northeast-oriented lower-level wave train over the WNP associated with anomalous convection around the Maritime Continent in August 1996. This wave train induced anomalous cyclone and enhanced convection over the northeastern WNP, which provided a favorable background for TC genesis. Over the southwestern WNP, although monthly mean anomalies were unfavorable, the intraseasonal variation contributed to positive vorticity anomalies at the time and location of TC genesis. In contrast, both monthly anomalies and daily variations of environment factors were hostile to TC genesis during August 2014.

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“…Meanwhile, the significant negative correlation zones steadily located in the tropical eastern Pacific (TEP) from June to August. It may denote that the impact of the TEP SSTs is more important to TCGF in August (Hong et al ., 2016a).…”

Section: Possible Remote Forcing Effect Of Nta Sstsmentioning

confidence: 99%

Remote forcing effect of sea surface temperatures in the northern tropical Atlantic on tropical cyclone genesis over the Western North Pacific in July

Shi

Yin

2021

Intl Journal of Climatology

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In July 2020, neither genesis nor landfall of typhoons occurred in the western North Pacific (WNP). This was the first time that the "no-typhoon" phenomenon had occurred since 1949. This study analysed the variation in the tropical cyclone genesis frequency (TCGF) in the WNP in July over the past 40 years, including the corresponding atmospheric background circulation and the possible influence of tropical sea surface temperature (SST). The results revealed that the eastward and northward location of the western Pacific subtropical high (WPSH), the deepened and eastward expanded tropical monsoon trough (TMT) in the WNP, the active convection in the main body of TMT, the weakened southwest water vapour transport of the East Asian summer monsoon, as well as the strengthened and eastward expanded equatorial westerly wind were conducive to the tropical cyclone genesis in the WNP in July. Furthermore, we used regression analysis to explore the possible impact of tropical SSTs. We found that the relatively high SSTs in the northern tropical Atlantic (NTA) in June and July triggered a cyclonic circulation over the tropical East Pacific and NTA, resulting in strong upward motion. The airflow subsidence in the tropical central Pacific then caused the WPSH to extend westward and the easterly airflow on the south side of WPSH to strengthen, which weakened the WNP monsoon trough. Besides, the influence of warming NTA SSTs could be conveyed to the Indian Ocean and indirectly induce the enhancement of WPSH. Such a series of the large-scale circulation variations were not favourable for tropical cyclone genesis in the WNP. As a result, the TCGF was relatively low in July.Thus, one of the causes of the July 2020 "no-typhoon" phenomenon in the WNP could be the remote forcing effect of SST in NTA.

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Compounding factors causing the unusual absence of tropical cyclones in the western North Pacific during August 2014

Cited by 11 publications

References 28 publications

Increasing influence of central Pacific El Niño on the inter‐decadal variation of spring rainfall in northern Taiwan and southern China since 1980

Increasing influence of central Pacific El Niño on the inter‐decadal variation of spring rainfall in northern Taiwan and southern China since 1980

Distinct Western North Pacific Tropical Cyclogenesis During Inactive Intraseasonal Phase of August 1996 and 2014

Remote forcing effect of sea surface temperatures in the northern tropical Atlantic on tropical cyclone genesis over the Western North Pacific in July

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