Rocket emissions representation in atmospheric air quality models: the Short-Range atmospheric transport and reaction of gases released by solid propellant engines

One risk associated with rocket-launching activities is the inhalation of exhaust gases, which can occur either in the vicinity of the launch pad or, depending on the way these gases are transported and dispersed through the atmosphere, at locations far from the launch pad. Immediately after the ignition of the rocket motors, a large, hot cloud is formed near the ground, composed of carbon monoxide (CO) and carbon dioxide (CO2), hydrogen chloride (HCl) and also particulate material composed of aluminium oxide (Al2O3) in the case of rockets driven by a solid propellant. The Weather Research and Forecasting Model (WRF), an atmospheric mesoscale model, was modified in the present study to simulate the transport, dispersion and chemistry mechanisms (with the addition of reactions involving HCl and other chlorinated compounds) of these gases released during a launch. Simulations of the dispersion of effluents were performed for different rainfall regimes (dry and rainy periods) as well as for atmospheric thermal stability (day- and night-time conditions) for a specific rocket (the Veiculo Lancador de Satelites, VLS) at Brazil's Alcantara Launch Center (Centro de Lancamento de Alcantara, CLA). The results show that the most critical levels of HCl and CO occurred on the launch pad (Setor de PreparacAo de Lancamento, SPL) from the time of the launch (t(0)) to 10 min. The village of Alcantara, which is 9 km from the launch pad, could be affected according to the wind direction. The concentration of HCl reached a level in the range of 2200-3800ppmv for both dry and wet periods respectively, and these concentrations can be very hazardous to humans.