In situ measurements of ice saturation in young contrails

Kaufmann, Stefan H. E.; Voigt, Christiane; Jeßberger, Philipp; Jurkat, Tina; Schläger, Hans; Schwarzenböeck, Alfons; Klingebiel, Marcus; Thornberry, T. D.

doi:10.1002/2013gl058276

Cited by 41 publications

(38 citation statements)

References 42 publications

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“…Hence, as shown in Fig. 1, long-lived contrails also exist in subsaturated air (as observed by Iwabuchi et al, 2012;and Kaufmann et al, 2014).…”

Section: Contrail Propertiessupporting

confidence: 55%

“…Horizontal diffusivities are larger because horizontal motions are not limited by stratification. The contrail bulk ice physics is approximated as a function of ice water content and ice particle number (N ice ) per flight distance assuming saturation inside the contrail, which is justified for dense ice clouds or slow humidity changes (Korolev and Mazin, 2003;Kaufmann et al, 2014). The local ice particle concentration (n ice ) is computed from the number of ice particles per flight distance divided by the plume cross section.…”

Section: The Contrail Simulation Model Cocipmentioning

confidence: 99%

“…The number of ice particles per unit plume length stays constant in the model except for parameterized losses by ice particle aggregation and turbulent mixing. (For a discussion of the aggregation model used, see Kienast-Sjögren et al (2013).) In each contrail segment, the volume mean particle radius r vol is computed from the volume of the ice and the particle number.…”

Section: The Contrail Simulation Model Cocipmentioning

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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“…Hence, as shown in Fig. 1, long-lived contrails also exist in subsaturated air (as observed by Iwabuchi et al, 2012;and Kaufmann et al, 2014).…”

Section: Contrail Propertiessupporting

confidence: 55%

Section: The Contrail Simulation Model Cocipmentioning

confidence: 99%

Section: The Contrail Simulation Model Cocipmentioning

confidence: 99%

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Dehydration effects from contrails in a coupled contrail–climate model

et al. 2015

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“…Fall streaks of contrails, which originate from sedimenting ice particles are not considered here, since they cannot be identified by NO y peaks. The observations enhance the existing data base of contrail observations (e.g., [82,85,[89][90][91]) as compiled by Schumann et al [92]. The data will be used to investigate radiation extinction by contrails, and can be compared to satellite retrievals and model results.…”

Section: Detection Of Contrails During Ml-cirrus 50mentioning

confidence: 94%

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

et al. 2017

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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.

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“…As a consequence, novel concepts and instruments (e.g. Thornberry et al, 2013;Kaufmann et al, 2014;Kaufmann et al, 2016;Buchholz et al, 2017) and improved techniques for inflight (Rollins et al, 2011) and ground calibration (Meyer et al, 2015) were developed to improve the accuracy of H 2 O measurements.…”

Section: Introductionmentioning

confidence: 99%

Intercomparison of mid-latitude tropospheric and lower stratospheric water vapor measurements and comparison to ECMWF humidity data

Kaufmann¹,

Voigt²,

Heller³

et al. 2018

Preprint

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Abstract. Accurate measurement of water vapor in the climate sensitive region near the tropopause turned out to be very challenging. Unexplained systematic discrepancies between measurements at low water vapor mixing ratios made by different instruments on airborne platforms have limited our ability to adequately address a number relevant scientific questions on the humidity distribution, cloud formation and climate impact in that region. Therefore, during the past decade, the scientific community has undertaken substantial efforts to understand these discrepancies and improve the quality of 20 water vapor measurements. This study presents a comprehensive intercomparison of airborne state-of-the-art in situ hygrometers deployed onboard the DLR (German Aerospace Center) research aircraft HALO during the Mid-Latitude CIRRUS (ML-CIRRUS) campaign conducted in 2014 over central Europe. The instrument intercomparison shows that the hygrometer measurements agree within their combined accuracy (±10 to 15%, depending on the humidity regime), total mean values even agree within 2.5%. However, systematic differences on the order of 10% and up to a maximum of 15% are 25 found for mixing ratios below 10 parts per million (ppm) H 2 O. A comparison of relative humidity within cirrus clouds does not indicate a systematic instrument bias in either water vapor or temperature measurements in the upper troposphere.Furthermore, in situ measurements are compared to model data from the European Centre for Medium-Range Weather Forecasts (ECMWF) which are interpolated along the ML-CIRRUS flight tracks. We find a mean agreement within ±10% throughout the troposphere and a significant wet bias in the model on the order of 100% to 150% in the stratosphere close to 30 the tropopause. Consistent with previous studies, this analysis indicates that the model deficit is mainly caused by a blurred humidity gradient at tropopause altitudes.Atmos. Chem. Phys. Discuss., https://doi

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In situ measurements of ice saturation in young contrails

Cited by 41 publications

References 42 publications

Dehydration effects from contrails in a coupled contrail–climate model

Dehydration effects from contrails in a coupled contrail–climate model

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

Intercomparison of mid-latitude tropospheric and lower stratospheric water vapor measurements and comparison to ECMWF humidity data

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