Boundary Layer Processes Modulate Track Shifts in a Landfalling Tropical Cyclone Through Storm Asymmetries

Abstract As a tropical cyclone (TC) approaches landfall, planetary boundary layer (PBL) processes are known to influence storm intensity and structure, but their role in TC track prediction remains unclear. Here we examine how PBL parameterization affects TC track prediction using Super Typhoon Saola (2023) as a case study. Simulated tracks using two PBL schemes are similar during the early stage but diverge markedly near landfall. Relative to the Yonsei University (YSU) scheme, the Mellor–Yamada–Janjic (MYJ) scheme produces a pronounced rightward track bias and delayed landfall, even with spectral nudging applied. Diagnosis of potential vorticity (PV) tendency shows that this bias arises from changes in diabatic heating (DH) and horizontal advection (HA). The MYJ scheme modifies asymmetric flow and convection in the lower–middle troposphere, while nudging alters the large‐scale steering flow in the middle–upper troposphere. These processes redistribute DH and HA contributions to PV tendency, producing a systematic rightward displacement of the TC track. These results demonstrate that PBL parameterization directly influences TC motion near landfall through its control of PV tendency and highlight the need to improve boundary layer representation in numerical weather prediction models.