Variations in Low‐Level Temperature Inversions Over the Marginal Ice Zone During Cyclone Passing: Effects of Abrupt Sea Ice Transitions

Abstract During cyclone passing in the summer melt season, low‐level atmospheric characteristics (e.g., temperature inversions) over the marginal ice zone (MIZ) exhibit a more pronounced response and distinctive variations than other ice zones, as influenced by abrupt sea ice transitions in the MIZ. Here, we constructed a high‐resolution model for the Pacific Arctic Region (PAR) using the polar‐optimized Weather Research and Forecasting model (PWRF), applied it to simulate the low‐level atmosphere during the 2018 Chinese National Arctic Research Expedition (CHINARE‐2018), and were able to accurately reproduce the observed conditions. Simulations, combined with observational data, were used to evaluate and investigate extreme variations in inversions over the MIZ. Analysis of 84 observed inversions revealed that inversion variability increased significantly during cyclone passing, with a specific inversion of extreme variations occurring in the MIZ. Simulation results showed that abrupt sea ice transitions in the MIZ triggered boundary‐layer destabilization, setting it apart from other ice zones and leading to these extreme inversion variations. Before the abrupt sea ice transitions occurred, inversions were mainly controlled by warm advection induced by the cyclone, which facilitated the formation of low‐level clouds. Following the transitions, increased surface turbulent fluxes destabilized the boundary‐layer, triggering strong upward motion. Meanwhile, accumulated moisture and energy promoted convection, lifting the clouds and inversions. Adiabatic cooling and radiative cooling at the cloud‐top over the MIZ led to the formation of inversions reaching the highest altitudes and lowest temperatures during CHINARE‐2018, fully capping the cloud‐top.