The D region of Earth’s ionosphere (60–90 km altitude) exerts a critical, yet often overlooked, influence on high-frequency (HF) radio propagation. This session focuses on how natural atmospheric chemistry, anthropogenic chemical releases (e.g., rocket exhaust, suborbital missions), and metallic ions from meteors and space debris shape D region dynamics and subsequently impact HF signal transmission. We invite observational, experimental, and modeling studies on topics such as: D region electron density and composition variability; chemical, electromagnetic, and dynamical drivers—including solar flares, particle precipitation, and metallic ion inputs; and consequences for HF signal attenuation, reflection, and absorption. Work advancing mitigation strategies for D region influences on HF disruption is also welcome. This interdisciplinary session seeks research from atmospheric chemistry, ionospheric physics, space weather, aeronomy, and applied radio science communities to deepen understanding of D region processes and their real-world impacts on HF radio propagation.

• A - Atmospheric Sciences
• SH - SPA-Solar and Heliospheric Physics