THE USE OF AN ATMOSPHERIC MODEL FOR STUDY THE GAS DISPERSION AT THE BRAZILIAN SPACE LAUNCHING CENTER

The present work aims to use an atmospheric mesoscale model (Weather Research and Forecasting model WRF) coupled with its chemical module (CHEM) in order to study the simulation of the dispersion of exhausted gas released from a typical rockets (in this case the Satellite Vehicle Launcher characteristics was used) from the Alcantara Launch Center (ALC). For the initialization of the coupled model, the preprocessor PREP-Chem was assigned to the Reanalysis of the TROpospheric chemical composition (RETRO). However, as this repository has no pollutants at the ALC area, a new method of insertion of chemical data assigned to the exact geographical position where the VLS is launched was used with all emissions null unless at the Launcher pad. Also, the model was initialized with meteorological data extracted from the Global Forecasting System (GFS). The simulations were made for different 4 cases representatives of the diurnal (daytime and nighttime) and seasonal (dry and wet seasons) scales. Observational data (radiosondes and wind tower data) was used to validate the wind field. There are 3 grids nested with 9, 3 and 1 km spatial resolution and the model has 45 levels in the vertical (15 levels up to 2000 m). All the simulations showed approximately the same patterns as the wind flow are very persistent (this is a characteristic of the trade winds). Typically, the simulations showed that the CO concentration (the variable used to represent the gases exhausted by the solid motors) at the launch pad is 2 order of magnitude higher than at the gate (1 km far) and 4 order of magnitude higher than Alcantara village (20 km far). It can reach 30000 ppm at the launching pad after Ho + 1 min. Also, it was computed that the launch pad must stay isolated by 15 min before any other action for the complete dispersion and, consequently, for safety reasons. As the turbulent intensity is higher at 12 UTC (daytime conditions), the total time for the complete dispersion of the plume is reduced (around 40-45 min) related to the nighttime conditions (60-75 min). This is an ongoing work that aims to improve this model configuration to include a vertical distribution of the exhausted gases due to the normal launching and to include small scale features at the scale of 100 m. In the near future, this model should be operational for the launchings at ALC.