Study of contrail microphysics in the vortex phase with a Lagrangian particle tracking model S. Unterstrasser and I. Sölch Deutsches Zentrum für Luft- und Raumfahrt (DLR) – Institut für Physik der Atmosphäre, Oberpfaffenhofen, 82234 Wessling, Germany
Abstract. Crystal sublimation/loss is a dominant feature of the contrail evolution during the vortex
phase and has a substantial impact on the later contrail-to-cirrus transition. Previous
studies showed that the fraction of crystals surviving the vortex phase depends primarily on
relative humidity, temperature and the aircraft type. An existing model for contrail vortex
phase simulations (with a 2-moment bulk microphysics scheme) was upgraded with a newly
developed state-of-the-art microphysics module (LCM) which uses Lagrangian particle
tracking. This allows for explicit process-oriented modelling of the ice crystal size
distribution in contrast to the bulk approach. We show that it is of great importance to
employ an advanced microphysics scheme to determine the crystal loss during the vortex
phase. The LCM-model shows even larger sensitivities to the above mentioned key parameters
than previously estimated with the bulk model. The impact of the initial crystal number is
studied and for the first time also the initial width of the crystal size distribution. Both
are shown to be relevant. This corroborates the need for a realistic representation of
microphysical processes and knowledge of the ice phase characteristics.
Citation: Unterstrasser, S. and Sölch, I.: Study of contrail microphysics in the vortex phase with a Lagrangian particle tracking model, Atmos. Chem. Phys., 10, 10003-10015, doi:10.5194/acp-10-10003-2010, 2010.