Global radiative forcing from contrail cirrus

Burkhardt, Ulrike; Kärcher, B.

doi:10.1038/nclimate1068

Cited by 321 publications

(360 citation statements)

References 42 publications

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“…contrail cirrus. A similar conclusion, but on a global scale, was drawn by Burkhardt and Kärcher (2011) based on results of a global climate model that was extended by a contrail cirrus module to simulate the life cycle of this anthropogenic cloud type.…”

Section: Introductionsupporting

confidence: 63%

Influence of particle size and shape on the backscattering linear depolarisation ratio of small ice crystals – cloud chamber measurements in the context of contrail and cirrus microphysics

et al. 2012

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Abstract. The article presents the laser scattering and depolarisation instrument SIMONE that is installed at the large aerosol and cloud chamber facility AIDA of the Karlsruhe Institute of Technology. SIMONE uses a 488 nm cw laser to probe simulated atmospheric clouds by measuring the scattered light from the 1.8 • and 178.2 • directions. At 178.2 • , the scattered light is analysed for the linear polarisation state to deduce the particle linear depolarisation ratio δ p which is a common measurement parameter of atmospheric lidar applications. The optical setup and the mathematical formalism of the depolarisation detection concept are given. SIMONE depolarisation measurements in spheroidal hematite aerosol and supercooled liquid clouds are used to validate the instrument.SIMONE data from a series of AIDA ice nucleation experiments at temperatures between 195 and 225 K were analysed in terms of the impact of the ice particle microphysics on δ p . We found strong depolarisation values of up to 0.4 in case of small growing and sublimating ice particles with volume equivalent diameters of only a few micrometers.Modelling runs with the T-matrix method showed that the measured depolarisation ratios can be accurately reproduced assuming spheroidal and cylindrical particles with a size distribution that has been constrained by IR extinction spectroscopy. Based on the T-matrix modelling runs, we demonstrate that in case of small ice crystals the SIMONE depolarisation results are representative for the lidar depolarisation ratio which is measured at exact backscattering direction of 180 • .The relevance of our results for the interpretation of recent lidar observations in cirrus and contrails is discussed. In view of our results, the high depolarisation ratios observed by the spaceborne lidar CALIOP in the tropical upper troposphere might be a hint for the presence of small (sublimating) ice particles in the outflows of deep convective systems.

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Section: Introductionsupporting

confidence: 63%

Influence of particle size and shape on the backscattering linear depolarisation ratio of small ice crystals – cloud chamber measurements in the context of contrail and cirrus microphysics

et al. 2012

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“…Contrail cirrus coverage varies both spatially and temporally, mainly dependent on the synoptic situation . The global radiative forcing of contrail cirrus, including an offsetting component arising from the reduction of natural cirrus, was found to exceed that of previously accumulated aircraft carbon dioxide emissions, making contrail cirrus the single largest radiative forcing (RF) component associated with aviation (Burkhardt and Kärcher, 2011). The RF of contrail cirrus was also found to be much larger than that of line-shaped contrails only.…”

Section: Introductionmentioning

confidence: 86%

Effects of optical depth variability on contrail radiative forcing

Kärcher

Burkhardt

2012

Quart J Royal Meteoro Soc

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Line-shaped contrails arising from aircraft emissions affect radiative forcing. The magnitude of the radiative forcing from contrails depends strongly on their optical depth and their spatial and temporal variability caused by dynamical and microphysical processes. Here we investigate the significance of this variability, both for modelling contrail radiative forcing and estimating thresholds for the detection of contrails in satellite imagery. Ignoring the variability of contrail optical depth in models by prescribing a mean optical depth may overestimate mean net radiative forcing by 10−20%. Undersampling of optically thin line-shaped contrails by passive satellite remote sensing is linked to the inability to detect flux changes in the outgoing long-wave radiation below ≈ 3 W m −2 for conditions over the eastern North Pacific. Consideration of these findings aids efforts to better quantify uncertainties in aviation climate assessments.

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“…With the increasing number of aircraft, the air traffic's contribution to climate change becomes an important problem. Nowadays, aircraft emission (this includes still uncertain aviation-induced cirrus cloud effects) contributes approximately 4.9 % (with a range of 2-14 %, which is a 90 % likelihood range) of the total anthropogenic radiative forcing (Lee et al, 2009;Lee et al, 2010;Burkhardt and Kärcher, 2011). An Airbus forecast shows that the world air traffic might grow at an average annual rate of 4.6 % over the next 20 years ( -2034( , Airbus, 2015, while Boeing forecasts a value of 4.9 % over the same period (Boeing, 2015).…”

Section: Introductionmentioning

confidence: 99%

Air traffic simulation in chemistry-climate model EMAC 2.41: AirTraf 1.0

et al. 2016

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Abstract. Mobility is becoming more and more important to society and hence air transportation is expected to grow further over the next decades. Reducing anthropogenic climate impact from aviation emissions and building a climatefriendly air transportation system are required for a sustainable development of commercial aviation. A climate optimized routing, which avoids climate-sensitive regions by rerouting horizontally and vertically, is an important measure for climate impact reduction. The idea includes a number of different routing strategies (routing options) and shows a great potential for the reduction. To evaluate this, the impact of not only CO 2 but also non-CO 2 emissions must be considered. CO 2 is a long-lived gas, while non-CO 2 emissions are short-lived and are inhomogeneously distributed. This study introduces AirTraf (version 1.0) that performs global air traffic simulations, including effects of local weather conditions on the emissions. AirTraf was developed as a new submodel of the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model. Air traffic information comprises Eurocontrol's Base of Aircraft Data (BADA Revision 3.9) and International Civil Aviation Organization (ICAO) engine performance data. Fuel use and emissions are calculated by the total energy model based on the BADA methodology and Deutsches Zentrum für Luft-und Raumfahrt (DLR) fuel flow method. The flight trajectory optimization is performed by a genetic algorithm (GA) with respect to a selected routing option. In the model development phase, benchmark tests were performed for the great circle and flight time routing options.The first test showed that the great circle calculations were accurate to −0.004 %, compared to those calculated by the Movable Type script. The second test showed that the optimal solution found by the algorithm sufficiently converged to the theoretical true-optimal solution. The difference in flight time between the two solutions is less than 0.01 %. The dependence of the optimal solutions on the initial set of solutions (called population) was analyzed and the influence was small (around 0.01 %). The trade-off between the accuracy of GA optimizations and computational costs is clarified and the appropriate population and generation (one iteration of GA) sizing is discussed. The results showed that a large reduction in the number of function evaluations of around 90 % can be achieved with only a small decrease in the accuracy of less than 0.1 %. Finally, AirTraf simulations are demonstrated with the great circle and the flight time routing options for a typical winter day. The 103 trans-Atlantic flight plans were used, assuming an Airbus A330-301 aircraft. The results confirmed that AirTraf simulates the air traffic properly for the two routing options. In addition, the GA successfully found the time-optimal flight trajectories for the 103 airport pairs, taking local weather conditions into account. The consistency check for the AirTraf simulations confirmed that calculated flight time, fuel consumption, NO ...

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Global radiative forcing from contrail cirrus

Cited by 321 publications

References 42 publications

Influence of particle size and shape on the backscattering linear depolarisation ratio of small ice crystals – cloud chamber measurements in the context of contrail and cirrus microphysics

Influence of particle size and shape on the backscattering linear depolarisation ratio of small ice crystals – cloud chamber measurements in the context of contrail and cirrus microphysics

Effects of optical depth variability on contrail radiative forcing

Air traffic simulation in chemistry-climate model EMAC 2.41: AirTraf 1.0

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