Abstract

Understanding wind direction (WD) variability and vertical directional shear is critical for aviation safety, particularly during landing when aircraft are highly sensitive to abrupt wind changes. This study analyzes the temporal behavior of WD and low-level directional shear over Baghdad International Airport during representative months of 2024 (January, April, July, and October) using hourly ERA5 u and v wind components at 10 and 540 m. Circular statistical measures quantify WD variability, while directional shear roses and absolute directional shear change rates characterize vertical wind alignment and shear intensity relevant to aviation operations. The results reveal pronounced seasonal contrasts. Summer (July) shows the most stable wind regime with strong directional persistence and weak shear (<~0.1–0.15 °/m), winter (January) is generally stable but punctuated by synoptic shear peaks up to ~0.85 °/m, spring (April) exhibits moderate and more variable shear (~0.1–0.45 °/m), and autumn (October) is the most dynamically unstable, with reduced persistence and frequent shear maxima approaching ~0.9–0.95 °/m. Circular standard deviation (σdir), is highest in winter–spring (mea n≈ 38° in January and ≈34° in April), weakest in summer (≈16–17° in July), and increases again in autumn (≈28–33° in October), reflecting seasonal changes in atmospheric forcing. σdir exhibits a clear seasonal cycle, with highest values during winter and spring and the most stable conditions in summer. These results show that integrating ERA5-based circular wind statistics with directional shear diagnostics effectively identifies aviation-critical wind regimes, while future multi-year and aircraft-based analyses can further refine operational low-level wind shear risk thresholds.

IPC Classification

Keywords