Contrail ice particles in aircraft wakes and their climatic importance

Schumann, U.; Jeßberger, Philipp; Voigt, Christiane

doi:10.1002/grl.50539

Cited by 51 publications

(71 citation statements)

References 38 publications

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“…All collected data show a similar trend: weaker relative turbulence leads to longer lifespan (as observed for example by . Similar trends were recently reported using the normalized Brunt-Väisälä frequency N * = N t 0 and the vortex sinking distance z b = w 0 × t b instead of the vortex lifespan t b (Schumann, 2012;Jeßberger et al, 2013;Schumann et al, 2013), and Fig. 7 shows a general good agreement with those data.…”

Section: Dynamics Of Wake Vorticessupporting

confidence: 89%

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

et al. 2015

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Abstract. In this work, the evolution of contrails in the vortex and dissipation regimes is studied by means of fully three-dimensional large-eddy simulation (LES) coupled to a Lagrangian particle tracking method to treat the ice phase. In this paper, fine-scale atmospheric turbulence is generated and sustained by means of a stochastic forcing that mimics the properties of stably stratified turbulent flows as those occurring in the upper troposphere and lower stratosphere. The initial flow field is composed of the turbulent background flow and a wake flow obtained from separate LES of the jet regime. Atmospheric turbulence is the main driver of the wake instability and the structure of the resulting wake is sensitive to the intensity of the perturbations, primarily in the vertical direction. A stronger turbulence accelerates the onset of the instability, which results in shorter contrail descent and more effective mixing in the interior of the plume. However, the self-induced turbulence that is produced in the wake after the vortex breakup dominates over background turbulence until the end of the vortex regime and controls the mixing with ambient air. This results in mean microphysical characteristics such as ice mass and optical depth that are slightly affected by the intensity of atmospheric turbulence. However, the background humidity and temperature have a first-order effect on the survival of ice crystals and particle size distribution, which is in line with recent studies.

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Section: Dynamics Of Wake Vorticessupporting

confidence: 89%

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

et al. 2015

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“…The number of soot particles emitted is set to be proportional to the fuel consumption with a fixed emission index (10 × 10 14 kg −1 ). The emission index used here is larger than in earlier studies (3.57 × 10 14 kg −1 ) because recent experimental data indicate that modern aircraft emit more (by number) soot particles acting as contrail ice nuclei than estimated earlier (Schumann et al, 2013b).…”

Section: The Contrail Simulation Model Cocipmentioning

confidence: 75%

“…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.…”

Section: The Contrail Simulation Model Cocipmentioning

confidence: 99%

“…The differences of the present study from previous results using CoCiP come mainly from the larger soot number emission index (10 15 kg −1 instead of ∼ 3.5 × 10 14 kg −1 ). For a factor-2 increase in the soot emission index, we computed increases in visible contrail cover of 1.29, in contrail age of 1.16, in U. Schumann et al: Dehydration effects from contrails in a coupled contrail-climate model contrail width of 1.22, in contrail geometrical depth of 1.14, and in net contrail RF of 1.64 (Schumann et al, 2013b).…”

Section: Some Global Contrail Propertiesmentioning

confidence: 99%

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Dehydration effects from contrails in a coupled contrail–climate model

et al. 2015

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Abstract. The uptake of water by contrails in icesupersaturated air and the release of water after ice particle advection and sedimentation dehydrates the atmosphere at flight levels and redistributes humidity mainly to lower levels. The dehydration is investigated by coupling a plumescale contrail model with a global aerosol-climate model. The contrail model simulates all the individual contrails forming from global air traffic for meteorological conditions as defined by the climate model. The computed contrail cirrus properties compare reasonably with theoretical concepts and observations. The mass of water in aged contrails may exceed 10 6 times the mass of water emitted from aircraft. Many of the ice particles sediment and release water in the troposphere, on average 700 m below the mean flight levels. Simulations with and without coupling are compared. The drying at contrail levels causes thinner and longer-lived contrails with about 15 % reduced contrail radiative forcing (RF). The reduced RF from contrails is on the order of 0.06 W m −2 , slightly larger than estimated earlier because of higher soot emissions. For normal traffic, the RF from dehydration is small compared to interannual variability. A case with emissions increased by 100 times is used to overcome statistical uncertainty. The contrails impact the entire hydrological cycle in the atmosphere by reducing the total water column and the cover by high-and low-level clouds. For normal traffic, the dehydration changes contrail RF by positive shortwave and negative longwave contributions on the order of 0.04 W m −2 , with a small negative net RF. The total net RF from contrails and dehydration remains within the range of previous estimates.

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“…In future, open questions regarding contrail microphysics Jeßberger et al, 2013;Schumann et al, 2013) and the persistence of contrails (Gayet et al, 2012;Kübbeler et al, 2011) will be addressed using ML-CIRRUS data from AIMS-H 2 O. In addition, we will perform a thorough intercomparison of the set of water vapor instruments operated on HALO to assess the quality of water vapor in situ measurements in the lower stratosphere in mid-latitudes.…”

Section: Discussionmentioning

confidence: 99%

The airborne mass spectrometer AIMS – Part 1: AIMS-H<sub>2</sub>O for UTLS water vapor measurements

et al. 2016

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Abstract. In the upper troposphere and lower stratosphere (UTLS), the accurate quantification of low water vapor concentrations has presented a significant measurement challenge. The instrumental uncertainties are passed on to estimates of H 2 O transport, cloud formation and the role of H 2 O in the UTLS energy budget and resulting effects on surface temperatures. To address the uncertainty in UTLS H 2 O determination, the airborne mass spectrometer AIMS-H 2 O, with in-flight calibration, has been developed for fast and accurate airborne water vapor measurements.We present a new setup to measure water vapor by direct ionization of ambient air. Air is sampled via a backward facing inlet that includes a bypass flow to assure short residence times (< 0.2 s) in the inlet line, which allows the instrument to achieve a time resolution of ∼ 4 Hz, limited by the sampling frequency of the mass spectrometer. From the main inlet flow, a smaller flow is extracted into the novel pressurecontrolled gas discharge ion source of the mass spectrometer. The air is directed through the gas discharge region where ion-molecule reactions lead to the production of hydronium ion clusters, H 3 O + (H 2 O) n (n = 0, 1, 2), in a complex reaction scheme similar to the reactions in the D-region of the ionosphere. These ions are counted to quantify the ambient water vapor mixing ratio. The instrument is calibrated during flight using a new calibration source based on the catalytic reaction of H 2 and O 2 on a Pt surface to generate a calibration standard with well-defined and stable H 2 O mixing ratios. In order to increase data quality over a range of mixing ratios, two data evaluation methods are presented for lower and higher H 2 O mixing ratios respectively, using either only the H 3 O + (H 2 O) ions or the ratio of all water vapor dependent ions to the total ion current. Altogether, a range of water vapor mixing ratios from 1 to 500 parts per million by volume (ppmv) can be covered with an accuracy between 7 and 15 %. AIMS-H 2 O was deployed on two DLR research aircraft, the Falcon during CONCERT (CONtrail and Cirrus ExpeRimenT) in 2011, and HALO during ML-CIRRUS (Mid-Latitude CIRRUS) in 2014. The comparison of AIMS-H 2 O with the SHARC tunable diode laser hygrometer during ML-CIRRUS shows a correlation near to 1 in the range between 10 and 500 ppmv for the entire campaign.

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Contrail ice particles in aircraft wakes and their climatic importance

Cited by 51 publications

References 38 publications

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

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

Dehydration effects from contrails in a coupled contrail–climate model

The airborne mass spectrometer AIMS – Part 1: AIMS-H<sub>2</sub>O for UTLS water vapor measurements

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Contrail ice particles in aircraft wakes and their climatic importance

Cited by 51 publications

References 38 publications

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

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

Dehydration effects from contrails in a coupled contrail–climate model

The airborne mass spectrometer AIMS – Part 1: AIMS-H&lt;sub&gt;2&lt;/sub&gt;O for UTLS water vapor measurements

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Product

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The airborne mass spectrometer AIMS – Part 1: AIMS-H<sub>2</sub>O for UTLS water vapor measurements