AUTHOR=Li Delin , Xiao Ziniu , Xu Jianjun , Zhao Liang 

TITLE=Asymmetric modulation of solar activity on tropical cyclone frequency over the western North Pacific and the possible mechanism

JOURNAL=Frontiers in Earth Science

VOLUME=Volume 11 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2023.1169685

DOI=10.3389/feart.2023.1169685

ISSN=2296-6463

ABSTRACT=The solar impacts on the tropical Pacific climate have been widely reported. But few studies focus on the effects of solar activity on the tropical cyclone (TC). Based on the observational and reanalysis data for 1979-2020, this study investigated the solar modulation on TC frequency over the western North Pacific in different solar cycle phases. Results suggest that the regressions of TC frequency to solar activity are obviously asymmetric in the high and low solar activity years (HS and    LS). Specifically, the intensified solar activity could markedly induce more TCs in HS, however, no significant modulation can be found in LS. Further exploration reveals a possible air-sea coupled mechanism for this interesting phenomenon. The relatively cloud-free area in the western North Pacific could avail more incoming solar radiation at surface in HS than that in LS. This increased regional surface net solar radiation in HS could produce stronger surface upward latent heat flux, and thus greater evaporation.Along with that, the local upward motion is dramatically enhanced over the TC source.Then for compensation, the regional sea level pressure is reduced and the low-level winds become cyclonic over the TC origin. All of these solar-caused regional atmospheric anomalies in HS contribute to more TC generations. The key for this possible mechanism is the regional increased solar forcing at ocean surface that being amplified by regional enhanced upward latent heat flux and evaporation.