Dependence of Atmospheric and Climate Impacts on Launch Latitude and Seasonal Variation in Rocket Emissions

Fri, 10 Oct 2025 00:00:00 +0000

Rocket launch emissions, dominated by black carbon, H2O, and NOx, are known to contribute to changes in atmospheric composition that can influence Earth’s climate, particularly for the large annual launch rates expected in the future. This study investigates the latitudinal and seasonal dependencies of the atmospheric impacts of rocket launch activities, examining how the annual timing of launches influences long-term climate impacts such as stratospheric temperature changes, ozone loss, and Effective Radiative Forcings. In each case, we simulate 20 years of launches using WACCM6, with the same annual launch frequency. To examine latitudinal dependencies, launches are simulated from six latitudes (55° S, 29° S, 0° N, 29° N, 55° N, and 70° N). To assess seasonal dependencies, three scenarios are considered (boreal summer-only, boreal winter-only, and boreal year-round launches). In terms of global stratospheric temperature changes, Northern Hemisphere launches generally produce less warming. In contrast, more severe ozone losses are observed for launches from the Northern Hemisphere. Seasonal dependency becomes more pronounced for launches closer to the equator, where the strong tropical meridional winds reverse direction between seasons.

Temporal black carbon concentration (kg BC kg⁻¹ air): year-round 70° N (top left), year-round 0° N (top right), boreal summer-only 0° N (bottom left), boreal winter-only 0° N (bottom right).

This work is in collaboration with Dr. Oliver Jia-Richards.

Development of a Plume Evolution Model for Launch Vehicle Ground Cloud Deposition

Fri, 10 Oct 2025 00:00:00 +0000

Solid rocket exhaust ground clouds contain high concentrations of toxic acidic compounds and particulate matter. Numerous efforts have been made to accurately predict their deposition; however, uncertainties increase substantially with varying atmospheric conditions. This study developed a plume evolution model to predict both near-field and far-field acidic deposition using a Lagrangian Particle Dispersion Model (LPDM) as the primary simulation framework. A dedicated cloud rise model was also developed to better capture the vertical evolution of rocket exhaust ground clouds, a critical factor influencing far-field deposition. The near-field, far-field, and cloud rise models were validated using observed data from recent studies. Our results demonstrated good agreement when compared with the observed data. The model was applied to the SpaceX Starship integrated flight test launches at the Starbase facility in Boca Chica, Texas. When combined with local wind statistics, the results indicate a significant potential for the ground cloud to reach nearby residential areas. Although Starship employs LOX/LCH₄ propellants, nitric oxide (NO) can form during the plume–air entrainment process, posing potential risks to human health.

Near-field deposition concentration plots simulated under surface wind conditions of 10 m s⁻¹ directed due east. In the 2D plot, the right side corresponds to the downwind direction. In the 3D plot, the positive y-axis corresponds to the downwind direction.

Far-field launch deposition results for SpaceX Starship integrated flight test 1, 2, and 3.

This work is supported by funding from the University of Michigan College of Engineering under the START program.

Rocket Launch Emissions | IDEAS Lab at University of Michigan

Dependence of Atmospheric and Climate Impacts on Launch Latitude and Seasonal Variation in Rocket Emissions

Development of a Plume Evolution Model for Launch Vehicle Ground Cloud Deposition