Exploring the uncertainties in the aviation soot-cirrus effect

Abstract

A global aerosol-climate model is applied to quantify the impact of aviation soot on natural cirrus clouds and to assess the uncertainties related to the ice nucleation abilities of aviation soot, the representation of vertical updrafts, and the use of nudging to relax the model dynamics. A radiative forcing in the range of -35 to 13 mW m-2 is simulated, depending on the assumed ice nucleation abilities of aviation soot. Idealized experiments with prescribed vertical velocities further show that the uncertainties on the model dynamics are important. Using the nudging technique is proved essential to identify statistically significant signals.