185 / 2026-03-01 00:23:23

Inactive Tropical Cyclone Strengthens Western North Pacific Anticyclone

西北太平洋反气旋；热带气旋；厄尔尼诺；

主题1 天气、气候、全球变化、行星大气 > 专题1.16 热带西太平洋多尺度过程及影响

Previous studies have examined the strengthening of the western North Pacific anticyclone (WNPAC) after the mature phase of El Niño from a large-scale perspective. This study demonstrates that the intensification of WNPAC is preceded by a reduction in western North Pacific tropical cyclones (WNPTCs) approximately 2 months earlier. By estimating the relative vorticity associated with WNPTCs, we find that reduced WNPTC activity accounts for about 33% of WNPAC variability from November of the El Niño year to September of the following year. This reduction is primarily driven by decreased relative humidity at 600 hPa, with low-level vorticity changes playing a minor role. Our finding of the significant impact of WNPTCs on the WNPAC aligns with the circulation theorem and enhances the dynamical understanding of WNPAC changes induced by El Niño.