Role of the Monsoon Gyre in the Interannual Variation of Tropical Cyclone Formation over the Western North Pacific

Abstract

The south-southeast periphery of a monsoon gyre in the western North Pacific (WNP) is a favorable region for tropical cyclone/tropical depression (TC/TD) genesis. The TC genesis frequency is interannually modulated by the WNP monsoon circulation in response to a change in tropical Pacific sea surface temperature (SST). These findings from previous studies lead to the hypothesis that the effect of tropical Pacific SST changes on the WNP TC/TD genesis frequency is accomplished through a modulation of the monsoon gyre activity by WNP monsoon circulation variations. The 6-h TC/TD track records and NCEP-NCAR reanalysis data for the period of 1979-2002 were analyzed to test this hypothesis. Results show that roughly 70% of WNP TC/TD geneses are linked to monsoon gyres. The interannual variation of these geneses is highly correlated (with a correlation coefficient of 0.89) with that of monsoon gyre activity, which is out-of-phase with the interannual variation of SST over the NOAA Nin ˜o-3 region.

Climatological analysis of passage-type tropical cyclones from the Western North Pacific into the South China Sea

“…Worldwide, TC activity is most intense over the WNP. TC formation is largely related to monsoon trough-related circulation features, including confluence zones, shear lines, and monsoon gyres (e.g., Ritchie and Holland 1999;Chen et al 2004;Yoshida and Ishikawa 2013). On average, the annual TC formation count in the WNP is about 25.7 (e.g., Neumann 1993).…”

Explaining Extreme Events of 2014 from a Climate Perspective

“…The variations of TC genesis frequency and intensity in the WNP, from intraseasonal to interdecadal time scales, are related to ISO phases (e.g., Gray 1979;Huang et al 2011;Li and Zhou 2013;, monsoon trough variability (e.g., Ritchie and Holland 1995;Chen et al 2004;Wu et al 2012), the El Niño-Southern Oscillation (e.g., Chan 2005;Du et al 2011;Kim et al 2011), and the PDO (e.g., Yang et al 2012;Liu and Chan 2013). WNP TC genesis frequency depends on the ISO phase ) and might also vary with different climate backgrounds of the EASM (Zhou et al 2009;Wang et al 2012) and PDO phase (Liu and Chan 2013).…”

Prediction of dominant intraseasonal modes in the East Asian-western North Pacific summer monsoon

“…The intraseasonal variability (ISV) of the East Asian-western North Pacific summer monsoon (EA-WNPSM), causing floods and droughts, links to the sequential passages of frontal systems, advance/retreat of the western North Pacific subtropical high (WNPSH), and tropical cyclone (TC) during June-July-August (JJA; Chen et al 2004). On the intraseasonal time scale, the East Asian summer monsoon (EASM) is categorized as the Changma (in Korea), Meiyu (in China), and Baiu (in Japan) with remarkable differences in their characteristics and rainy periods (Chang et al 1998;Kang et al 1999;LinHo and Wang 2002;Qian et al 2002;Ha et al 2005;Ha and Lee 2007).…”