DOI: 10.5522/04/30003763.v2
title: Atmospheric composition and radiative forcing changes from a decade of growth in megaconstellation emissions obtained using GEOS-Chem

description: Data here include GEOS-Chem simulation results in NetCDF format for the 3 emissions scenarios simulations to trace the changes in atmospheric composition and radiative forcing of a decade of growth in spacecraft launch and re-entry air pollutant emissions. Scenarios are distinguished by filenames including the words Baseline (no launch or re-entry emissions), AllMissions (all launch and re-entry mission emissions) and SMCMissions (only launch and re-entry emissions associated with megaconstellation missions).Specifically included are monthly means of radiative forcing, species concentrations, and stratospheric liquid aerosol surface area on the GEOS-Chem model grid. Also included are the pressure coordinates of the GEOS-Chem grid and the annual scaling factors used to scale the emissions to the end of the decade. Only the scaling factors are in CSV format. A detailed description of these outputs is in the Earth’s Future paper submitted for review.There are 7 types of data provided and summarised below.A compressed folder (aerosol_surface_area.tar.gz) containing outputs of stratospheric liquid aerosol surface area. The files are categorized as “<b>aerosol_{year}_{scenario}.nc4</b>”, where “year” is the simulation year, and “scenario” is the simulation (“Baseline”, “AllMissions”, “SMCMissions”). Units are cm<sup>2</sup> cm<sup>-3</sup>.<br>A compressed folder (radiative_forcing.tar.gz) containing outputs of radiative forcing. The files are categorized as “<b>rad_forcing_{scenario}_{forcing}.nc4</b>”, where “scenario” is the simulation (“Baseline”, “AllMissions”, “SMCMissions”), and “forcing” is the radiative forcing output (Instantaneous” or “Strat_Adjusted”). Units are W m<sup>-2</sup>.<br>A compressed folder (species_concentrations.tar.gz) containing outputs of species concentration. The files are categorized as “<b>species_conc_{year}_{scenario}.nc4</b>”, where “year” is the simulation year, and “scenario” is the simulation (“Baseline”, “AllMissions”, “SMCMissions”). Units are mixing ratio mol mol<sup>-1</sup> dry.<br>A single file in NetCDF format (pressure.nc4) describing the vertical pressure grid of GEOS-Chem, used for all simulations results.<br>A single file in csv format (annual_growth_factors.csv) describing the annual growth factors used to scale the 2020-2022 emissions to 2029. The scaling factors are separated into scaling factors for SMC and non-SMC emissions, and for launch and re-entry emissions. The scaling factors are unitless.<br>A single file in csv format (past-projected-spacecraft-launch-reentry-mass.csv) providing the values plotted in Figure 2(a) and Figure 2(b) of the manuscript. Specifically, the total annual mass of propellant burned and mass of re-entry for 2020-2029.<br>Image file (ATISPADE_Table47_Bekki2019.png) of the table from the ATISPADE study (reference: Beck, J., Merrifield, J., Spel, M., Lips, T., & Bekki, S. (2019, October 2). Aerothermodynamic Assessment of Atmospheric Emissions from Re-entry Demise. ESA International Conference on Flight Vehicles, Aerothermodynamics and Re-Entry Missions Engineering (FAR).) showing the range of pollutants released from re-entry ablation of spacecraft. The study report is not on a public repository, so the table of data referenced in our study is provided here.