Dimension of aircraft exhaust plumes at cruise conditions: effect of wake vortices

Abstract

Abstract. The dispersion of aircraft emissions during the vortex phase is studied using a 3-D LES model with Lagrangian particle tracking. The simulations start with a fully rolled-up vortex pair of a type B747/A340 airplane and the tracer centred around the vortex cores. The tracer dilution and plume extent is studied for a variety of ambient and aircraft parameters until aircraft-induced effects have ceased. For typical upper tropospheric conditions, the impact of stratification is more dominant compared to turbulence intensity or vertical wind shear. Moreover, the sensitivity to the initial tracer distribution was found to be weak. Along the transverse direction, the tracer concentrations can be well approximated by a Gaussian distribution, along the vertical a superposition of three Gaussian distributions is adequate. For the studied parameter range, the vertical plume expansion ranges from 400 m to 550 m and cross-sectional area from 4.0 × 10 4 m 2 to 6 × 10 4 m 2 after six minutes. For validation, selected simulations were compared to an alternative LES model and to in-situ NO-measurements.

Large-eddy simulation study of contrail microphysics and geometry during the vortex phase and consequences on contrail-to-cirrus transition

“…The initialization of the flow field is analogous to a recent wake vortex study [ Unterstrasser et al , ]. In the latter study, wake vortex simulations with dispersing passive tracers were performed with EULAG‐LCM.…”

Large-eddy simulation of contrail evolution in the vortex phase and its interaction with atmospheric turbulence

“…The latter authors also compared the results obtained with Eulerian-and Lagrangian-based methods on the same computational grid and observed that the LPT allows for a more accurate representation of ice microphysics. This aspect was recently investigated by Unterstrasser et al (2014) in the context of tracer dispersion in aircraft wake vortices. They observed that LPT appears to be less dissipative than Eulerian formulations in reproducing particle dispersion in aircraft wake vortices, although the details depend on the accuracy of the numerical scheme and the computational grid.…”

Contrail lobes or mamma? The importance of correct terminology

“…Other researchers have also simulated contrail lobes, confirming the essence of these results (e.g. Paugam et al ., ; Naiman et al ., ; Unterstrasser, ; Unterstrasser et al ., ; Picot et al ., ). With this large body of literature that has simulated and explained contrail lobe formation, we find it confusing that Paoli and Shariff (, p. 419) have subsequently asked, What is the mechanism of the intriguing and often‐observed mamma structures…?…”

“…The lobular cloud regions in contrails have been variously called ‘drop‐like formations’ and ‘pendulous lumps’ (Ludlam and Scorer, ), ‘blobs’ (Scorer and Davenport, ), ‘pendant swellings like inverted mushrooms’ (World Meteorological Organization, , p. 66), ‘pendules or fingers’ (Schaefer and Day, , p. 138), ‘puffs’ (Lewellen and Lewellen, ), ‘clumps of condensate’ (Rossow and Brown, ), ‘smoke rings’ (Unterstrasser et al, ), and ‘tear‐drop structures’ (Paoli and Shariff, ). They have also been called ‘mammatus’ (Ludlam and Scorer, ; Schultz et al, ; Unterstrasser et al, ), ‘akin to mammato‐cumulus’ (Day and Schaefer, ), and ‘mamma structures’ (Paoli and Shariff, ). This discrepancy in terminology in the literature (as well as public‐facing websites discussing contrails and meteorology) raises an important question as to what should be the appropriate scientific name for these features.…”