Inhomogeneous Sea‐Salt Aerosols—A New Strengthening Mechanism for the Western North Pacific Subtropical High

Abstract

Abstract The western North Pacific Subtropical High (WNPSH) significantly influences East Asian weather. In the Northwest Pacific where sea‐salt aerosols (SSAs) are abundant and the large‐scale environment is dominated by the dry subsidence of the WNPSH during summer, inhomogeneous SSAs form as a product of the environment. However, the extent to which inhomogeneous SSAs affect the WNPSH remains unclear. This study investigates the radiative effects of SSAs through numerical simulations, revealing a novel mechanism for the strengthening of the WNPSH. The results demonstrate that inhomogeneous SSAs enhance the WNPSH by generating diabatic cooling in the upper troposphere and associated unstable subsidence motion. Further considering the radiative hysteresis effects of inhomogeneous SSAs, the WNPSH further strengthens under the combined dynamic and thermodynamic influences associated with upper‐level radiative cooling. Inhomogeneous SSAs not only enhance the WNPSH but also influence the location where the central area of high pressure intensifies.