Quantitative Evaluation of Boundary Layer Disturbance Caused by Small Islands Based on Multi‐Scale Simulation

Abstract Understanding the extent and impact of small‐scale island wakes on the atmospheric boundary layer (ABL) is essential for advancing local meteorology. Using the high‐resolution WRF‐PALM nested model, we quantitatively evaluated the ABL disturbances caused by small‐scale islands. Sensitivity experiments with and without islands, conducted during both daytime and nighttime, were used to investigate the wake structures, their effects on near‐surface meteorology, and the underlying physical mechanisms. The results reveal notable diurnal variations in the wake structure. At night, orographic dynamics dominate, creating a wind sheltering effect in the leeward area, reducing wind speed, and forming a weak wind wake with downward motion near the surface. This reduces the upward kinematic turbulent sensible heat flux, inhibiting latent heat flux from the sea. During the day, thermal and dynamic forces contribute to a more complex wake structure, with accelerated airflows flanking the low‐speed wake on both sides. The convergence of wind streams induces upward motion and enhances wind‐driven mixing, thereby increasing turbulent sensible heat exchange within the wake zone. Even small islands induce substantial horizontal disturbances in the ABL, with the temperature wake at night extending 5.3 times the island's area and 5.9 times its length, reaching more than 15 km downstream. Thermal effects dominate over dynamic effects in influencing vertical ABL disturbances, increasing the disturbance heights of wind speed, potential temperature, and water vapor to 445 m, 665 m, and 675 m, respectively. These findings reveal the meteorological significance of small‐island wakes and their essential role in shaping local boundary‐layer processes.