Reassessing properties and radiative forcing of contrail cirrus using a climate model

Bock, Lisa; Burkhardt, Ulrike

doi:10.1002/2016jd025112

Cited by 73 publications

(121 citation statements)

References 65 publications

Supporting

Mentioning

107

Contrasting

Order By: Relevance

“…At temperatures close to the contrail formation threshold, maximum plume supersaturation limits the ice nucleation since only the larger soot or ambient particles entrained into the plume can activate into water droplets (Kärcher et al, 2015). Initial ice crystal number in global climate models has been calculated either from the water vapor available for deposition, assuming a fixed ice crystal size (Chen & Gettelman, 2013), or prescribed using a constant initial value inferred from in situ measurements (Bock & Burkhardt, 2016b) or set equal to engine soot number emissions accounting for different aircraft types (Schumann et al, 2015). The method of Chen and Gettelman (2013) introduces a dependency on the atmospheric state that only remotely relates to the nucleation process within contrails.…”

Section: Introductionmentioning

confidence: 99%

Variability in Contrail Ice Nucleation and Its Dependence on Soot Number Emissions

Bier

Burkhardt

2019

JGR Atmospheres

View full text Add to dashboard Cite

Contrail ice nucleation is mainly controlled by aircraft emissions and the atmospheric state. The nucleation rate can have a strong impact on microphysical processes, optical properties, lifetime, and, therefore, on the climate impact of contrail cirrus. We study contrail ice crystal formation offline for specified atmospheric conditions and its spatial variability in a global climate model. Assuming the standard atmosphere, above around 270 hPa (10 km) contrail ice nucleation is mainly controlled by aircraft soot number emissions and below additionally by atmospheric temperature. Parameterizing contrail ice nucleation in a global climate model, we find that in the northern extratropics contrails form frequently far away from their formation threshold. For current soot number emissions and in case of contrail formation, 90% of emitted soot particles form on average ice crystals around the cruise level and more than 70% between cruise altitudes and 300 hPa. The number of nucleated ice crystals in the extratropics decreases nearly at the same rate as soot number emissions. In contrast, in the tropics around cruise altitudes approximately 60% of contrails develop close to their formation threshold so that on average only about 50% of emitted soot particles can form ice crystals. Below, contrail formation occurs rarely and ice nucleation is reduced more strongly. Of the main air traffic areas, contrail ice nucleation is significantly limited by the atmospheric state over eastern Asia and over the southeastern United States. This limitation is enhanced during the summer months.

show abstract

Section: Introductionmentioning

confidence: 99%

Variability in Contrail Ice Nucleation and Its Dependence on Soot Number Emissions

Bier

Burkhardt

2019

JGR Atmospheres

View full text Add to dashboard Cite

show abstract

“…Long-lived contrails of significant optical thickness (> 0.1) are estimated to cover about 0.2-0.5 % of the Earth, with higher values in northern midlatitudes Schumann et al, 2015;Bock and Burkhardt, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Hence, λ p ∼ = 0.267 K W −1 m 2 for [dT s /dT p ] = 1. The feedback factor [dT s /dT p ] differs from 1 depending on the various forcing types (Stephens, 2005;Bony et al, 2006;Stevens and Bony, 2013). Therefore, λ is not a universal constant (Forster et al, 1997;Joshi et al, 2003;Stuber et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Various models to represent contrails in three-dimensional atmospheric global circulation models have been developed (Ponater et al, 1996;Rind et al, 2000;Ponater et al, 2002;Marquart et al, 2003;Rap et al, 2010b;Burkhardt and Kärcher, 2011;Jacobson et al, 2011;Olivié et al, 2012;Chen and Gettelman, 2013;Schumann et al, 2015;Bock and Burkhardt, 2016), with different treatments of traffic, subgrid-scale contrail formation, and optical properties. Some of these models were run with atmosphere-ocean coupling (Rind et al, 2000;Ponater et al, 2005;Rap et al, 2010a;Huszar et al, 2013;Jacobson et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Sensitivity of surface temperature to radiative forcing by contrail cirrus in a radiative-mixing model

Schumann

Mayer²

2017

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. Earth's surface temperature sensitivity to radiative forcing (RF) by contrail cirrus and the related RF efficacy relative to CO 2 are investigated in a one-dimensional idealized model of the atmosphere. The model includes energy transport by shortwave (SW) and longwave (LW) radiation and by mixing in an otherwise fixed reference atmosphere (no other feedbacks). Mixing includes convective adjustment and turbulent diffusion, where the latter is related to the vertical component of mixing by large-scale eddies. The conceptual study shows that the surface temperature sensitivity to given contrail RF depends strongly on the timescales of energy transport by mixing and radiation. The timescales are derived for steady layered heating (ghost forcing) and for a transient contrail cirrus case. The radiative timescales are shortest at the surface and shorter in the troposphere than in the midstratosphere. Without mixing, a large part of the energy induced into the upper troposphere by radiation due to contrails or similar disturbances gets lost to space before it can contribute to surface warming. Because of the different radiative forcing at the surface and at top of atmosphere (TOA) and different radiative heating rate profiles in the troposphere, the local surface temperature sensitivity to stratosphere-adjusted RF is larger for SW than for LW contrail forcing. Without mixing, the surface energy budget is more important for surface warming than the TOA budget. Hence, surface warming by contrails is smaller than suggested by the net RF at TOA. For zero mixing, cooling by contrails cannot be excluded. This may in part explain low efficacy values for contrails found in previous global circulation model studies. Possible implications of this study are discussed. Since the results of this study are model dependent, they should be tested with a comprehensive climate model in the future.

show abstract

“…The climate impact of exhaust contrails and the contrail cirrus resulting from them is a research topic since many years. In terms of RF it is estimated to be of the order 30-40 mW/m 2 with a quite large uncertainty [5,14,15,110,111]. The climate impact of aerodynamic contrails (Figure 16) is qualified to be very small compared to that of exhaust contrails [112], without providing a quantitative estimate of their RF.…”

mentioning

confidence: 99%

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

et al. 2017

View full text Add to dashboard Cite

Abstract:The WeCare project (Utilizing Weather information for Climate efficient and eco efficient future aviation), an internal project of the German Aerospace Center (Deutsches Zentrum für Luft-und Raumfahrt, DLR), aimed at finding solutions for reducing the climate impact of aviation based on an improved understanding of the atmospheric impact from aviation by making use of measurements and modeling approaches. WeCare made some important contributions to advance the scientific understanding in the area of atmospheric and air transportation research. We characterize contrail properties, show that the aircraft type significantly influences these properties, and how contrail-cirrus interacts with natural cirrus. Aviation NO x emissions lead to ozone formation and we show that the strength of the ozone enhancement varies, depending on where within a weather pattern NO x is emitted. These results, in combination with results on the effects of aerosol emissions on low cloud properties, give a revised view on the total radiative forcing of aviation. The assessment of a fleet of strut-braced wing aircraft with an open rotor is investigated and reveals the potential to significantly reduce the climate impact. Intermediate stop operations have the potential to significantly reduce fuel consumption. However, we find that, if only optimized for fuel use, they will have an increased climate impact, since non-CO 2 effects compensate the reduced warming from CO 2 savings. Avoiding climate sensitive regions has a large potential in reducing climate impact at relatively low costs. Taking advantage of a full 3D optimization has a much better eco-efficiency than lateral re-routings, only. The implementation of such operational measures requires many more considerations. Non-CO 2 aviation effects are not considered in international agreements. We showed that climate-optimal routing could be achieved, if market-based measures were in place, which include these non-CO 2 effects. An alternative measure to foster climate-optimal routing is the closing of air spaces, which are very climate-sensitive. Although less effective than an unconstrained optimization with respect to climate, it still has a significant potential to reduce the climate impact of aviation. By combining atmospheric and air transportation research, we assess climate mitigation measures, aiming at providing information to aviation stakeholders and policy-makers to make aviation more climate compatible.

show abstract

Reassessing properties and radiative forcing of contrail cirrus using a climate model

Cited by 73 publications

References 65 publications

Variability in Contrail Ice Nucleation and Its Dependence on Soot Number Emissions

Variability in Contrail Ice Nucleation and Its Dependence on Soot Number Emissions

Sensitivity of surface temperature to radiative forcing by contrail cirrus in a radiative-mixing model

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

Contact Info

Product

Resources

About