Aircraft‐type dependency of contrail evolution

Abstract

The impact of aircraft type on contrail evolution is assessed using a large eddy simulation model with Lagrangian ice microphysics. Six different aircraft ranging from the small regional airliner Bombardier CRJ to the largest aircraft Airbus A380 are taken into account. Differences in wake vortex properties and fuel flow lead to considerable variations in the early contrail geometric depth and ice crystal number. Larger aircraft produce contrails with more ice crystals (assuming that the number of initially generated ice crystals per kilogram fuel is constant). These initial differences are reduced in the first minutes, as the ice crystal loss during the vortex phase is stronger for larger aircraft. In supersaturated air, contrails of large aircraft are much deeper after 5 min than those of small aircraft. A parameterization for the final vertical displacement of the wake vortex system is provided, depending only on the initial vortex circulation and stratification. Cloud resolving simulations are used to examine whether the aircraft-induced initial differences have a long-lasting mark. These simulations suggest that the synoptic scenario controls the contrail cirrus evolution qualitatively. However, quantitative differences between the contrail cirrus properties of the various aircraft remain over the total simulation period of 6 h. The total extinctions of A380-produced contrails are about 1.5 to 2.5 times higher than those from contrails of a Bombardier CRJ.

Dehydration effects from contrails in a coupled contrail–climate model

“…The initial contrail properties (depth, width, number of ice particles, initial ice water content) are computed for given aircraft types. (The importance of aircraft size, speed, fuel consumption, and emissions for contrail properties was the subject of several recent studies (Lewellen and Lewellen, 2001;Naiman et al, 2011;Voigt et al, 2011;Jeßberger et al, 2013;Schumann et al, 2013b;Unterstrasser and Görsch, 2014).) The contrail advection and the shear-and turbulence-driven spreading and mixing of plume air with ambient air are simulated with a Gaussian plume model.…”

Mitigating the Climate Impact from Aviation: Achievements and Results of the DLR WeCare Project

“…Unterstrasser et al [104] deal with parameter variations that directly affect the wake vortex descent and break-up (thermal stratification, turbulence, initial vortex properties), whereas Unterstrasser [103] focuses on parameters directly relevant to contrail ice microphysics (temperature, relative humidity, soot emission index). In a next step, the importance of aircraft type on contrail evolution is assessed (ranging from a small regional airliner Bombardier CRJ to the largest aircraft A380 [105]). Differences in wake vortex properties and fuel flow affect the early contrail properties leaving a long-lasting mark over the simulated 6 hour period.…”

Sensitivity of particle loss to the Kelvin effect in LES of young contrails

“…In Naiman (2011), Naiman et al (2011), Inamdar et al (2013), Inamdar et al (2014 the parameter a k was explicitly calculated as a function of T but in other studies the Kelvin effect is neglected (Paoli et al, 2013;Paugam et al, 2010;Paoli et al, 2004) or a fixed order-of-magnitude value of a k is used (Picot et al, 2015). It is unclear to the authors exactly how the Kelvin effect is modeled in (Solch and Karcher, 2010) 20 and studies employing the same approach (Unterstrasser, 2014;Unterstrasser and Gorsch, 2014;.…”

“…Exclusion of jet exhaust enthalpy is a common modeling assumption (Unterstrasser, 2014;Unterstrasser and Gorsch, 2014;25 Unterstrasser et al, 2014;Jessberger et al, 2013;Unterstrasser and Solch, 2010) as it is expected to not have any persistent impact (Schumann, 2012)(their Appendix A6). Keeping in mind that several in-situ measurements provide data for young contrails (Febvre et al, 2009;Voigt et al, 2010;Gayet et al, 2012) and that Unterstrasser (2014)(their "Gaussian" cases in …”