Study of contrail microphysics in the vortex phase with a Lagrangian particle tracking model (vol 10, pg 10003, 2010)
- ISSN: 1680-7316
- DOI: 10.5194/acp-11-2787-2011
Crystal sublimation/loss is a dominant feature of the contrail evolution\nduring the vortex phase and has a substantial impact on the later\ncontrail-to-cirrus transition. Previous studies showed that the fraction\nof crystals surviving the vortex phase depends primarily on relative\nhumidity, temperature and the aircraft type. An existing model for\ncontrail vortex phase simulations (with a 2-moment bulk microphysics\nscheme) was upgraded with a newly developed state-of-the-art\nmicrophysics module (LCM) which uses Lagrangian particle tracking. This\nallows for explicit process-oriented modelling of the ice crystal size\ndistribution in contrast to the bulk approach. We show that it is of\ngreat importance to employ an advanced microphysics scheme to determine\nthe crystal loss during the vortex phase. The LCM-model shows even\nlarger sensitivities to the above mentioned key parameters than\npreviously estimated with the bulk model. The impact of the initial\ncrystal number is studied and for the first time also the initial width\nof the crystal size distribution. Both are shown to be relevant. This\ncorroborates the need for a realistic representation of microphysical\nprocesses and knowledge of the ice phase characteristics. cirrus\nproperties. Thus, in a first step Large Eddy Simulation models (LES)\nshould be used to better understand the contrail-to-cirrus transition\nand quantify the dominant atmospheric and aircraft parameters affecting\nit. Recently, the transition of single contrails into a contrail-cirrus\nwas extensively studied with a high resolution numerical model\n(Unterstrasser and Gierens, 2010a,b). Among other things these\nsimulations revealed that the early contrail evolution during the jet\nand vortex phase affects the optical properties and the lifetime of the\ncontrail-cirrus even hours later, emphasising the need for realistic\nvortex phase simulations.