21 Aug 2023
 | 21 Aug 2023

Sensitivities of atmospheric composition and climate to altitude and latitude of hypersonic aircraft emissions

Johannes Friedrich Pletzer and Volker Grewe

Abstract. Hydrogen-powered hypersonic aircraft are designed to travel in the middle stratosphere at approximately 30–40 km. These aircraft can have a considerable impact on climate-relevant species like stratospheric water vapour, ozone and methane and thus would contribute to climate warming. The impact of hypersonic aircraft emissions on atmospheric composition and in turn on radiation fluxes differs strongly depending on cruise altitude. However, in contrast to variation of altitude of emission, differences from variation of latitude of emission are currently unknown. Here we show that a variation in latitude of emission can have a larger effect on perturbations and stratospheric-adjusted radiative forcing than a variation of altitude of emission. Our results include individual impacts on middle atmospheric water vapour, ozone and methane, of water vapour and nitrogen oxide emissions, as well as unburnt hydrogen and the resulting radiative forcing. Water vapour perturbation lifetime continues the known tropospheric increase with altitude and reaches almost six years in the middle stratosphere. Our results demonstrate how atmospheric composition changes caused by emissions of hypersonic aircraft are controlled by large-scale processes like the Brewer-Dobson circulation and, depending on latitude of emission, local phenomena like polar stratospheric clouds.

The analysis includes a model evaluation of ozone and water vapour with satellite data and a novel approach to reduce simulated years by one-third and thus cost and climate impact. A prospect is the analysis of seasonal sensitivities and simulations with emissions from combustion of liquefied natural gas instead of liquid hydrogen.

Johannes Friedrich Pletzer and Volker Grewe

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1777', Anonymous Referee #1, 28 Sep 2023
    • AC1: 'Reply on RC1', Johannes Pletzer, 23 Nov 2023
  • RC2: 'Comment on egusphere-2023-1777', Anonymous Referee #2, 16 Oct 2023
    • AC2: 'Reply on RC2', Johannes Pletzer, 23 Nov 2023

Johannes Friedrich Pletzer and Volker Grewe

Johannes Friedrich Pletzer and Volker Grewe


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Short summary
Very fast aircraft can travel at 30–40 km altitude and are designed to use liquid hydrogen as fuel instead of kerosene. Depending on their flight altitude, the impact of these aircraft on atmosphere and climate can change very much. Our results show that a variation of flight latitude can have a considerably higher change in impact compared to a variation of flight altitude. Atmospheric air transport and polar stratospheric clouds play an important role for hypersonic aircraft emissions.