Simulation of Contrails in the vortex regime – Examination of the microphysical properties

Abstract

In the vortex regime the contrail development is governed by the wake dynamics. The major fraction of the ice crystals is trapped inside the downward travelling vortex pair. For ambient supersaturations below a certain threshold, none of the trapped crystals survive the vortex phase. Only crystals detrained during the descent form the contrail. The ambient relative humidity has a strong impact on the vertical extent of the contrail and on the number of surviving ice crystals, especially in the vortex. Contrail development during the vortex regime was modelled with ambient supersaturations ranging from 0% to 20%. The computationally cheap 2D-code permits a large number of simulations. A realistic vortex decay was ensured using parameterisations of 3Dsimulations. The obtained results give detailed information on initial states for contrail-to-cirrus simulations.