Observations of microphysical properties and radiative effects of contrail cirrus and natural cirrus over the North Atlantic

Wang, Ziming; Bugliaro, Luca; Jurkat‐Witschas, Tina; Heller, Romy; Burkhardt, Ulrike; Ziereis, H.; Dekoutsidis, Georgios; Wirth, Martin; Groß, Silke; Kirschler, Simon; Kaufmann, Stefan H. E.; Voigt, Christiane

doi:10.5194/acp-2022-537

Cited by 2 publications

(3 citation statements)

References 42 publications

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“…The increased humidity in the upper troposphere during the campaign period can contribute to more persistent contrails 495 which can be particularly warming (Wilhelm et al, 2022;Teoh et al, 2022;Wang et al, 2022). However, the potential contrail cirrus cover is the lowest during summer over Europe (Dischl et al, 2022).…”

Section: Relating Ice Cloud Microphysical Properties To the Location ...mentioning

confidence: 99%

“…A reduction of ED was observed from measurements near flight corridors by Kristensson et al (2000). Recent studies also showed a reduction in the effective radius of contrails embedded in natural cirrus (Wang et al, 2022;Li et al, 2022). However, depending on atmospheric conditions, when contrails are embedded in natural cirrus, the evolution of the contrail is perturbed by the cirrus and ice crystals from contrail and cirrus coexist, making it difficult to distinguish between them (Unterstrasser et al, 2017a, b).…”

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confidence: 99%

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Differences in microphysical properties of cirrus at high and mid-latitudes

Castro

Jurkat‐Witschas

Afchine³

et al. 2023

Preprint

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Abstract. Despite their proven significance for the atmospheric radiative energy budget, the effect of cirrus on climate and the magnitude of their modification by human activity is not well quantified. Besides anthropogenic pollution sources on the ground, aviation has a large local effect on cirrus microphysical and radiative properties via the formation of contrails and their transition to contrail cirrus. To investigate the anthropogenic influence on natural cirrus, we compare the microphysical properties of cirrus measured at mid-latitude regions (ML, < 60° N) that are often affected by aviation and pollution with cirrus measured in the same season in comparatively pristine high latitudes (HL, ≥ 60° N). The number concentration, effective diameter, and ice water content of the observed cirrus are derived from in situ measurements covering ice crystal sizes between between 2 and 6400 µm collected during the CIRRUS-HL campaign (CIRRUS in High Latitudes) in June and July 2021. We analyse the dependence of cirrus microphysical properties on altitude and latitude and demonstrate that the median ice number concentration is by an order of magnitude larger in the measured mid-latitude cirrus with 0.0086 cm-3 compared to 0.001 cm-3 in high-latitude cirrus. Ice crystals in mid-latitude cirrus are on average smaller than in high-latitude cirrus, with a median effective diameter of 165 µm compared to 210 µm and the median ice water content in mid-latitude cirrus is higher (0.0033 g m-3) than in high-latitude cirrus (0.0019 g m-3). In order to investigate the cirrus properties in relation to the region of formation, we combine the airborne observations with 10-day backward trajectories to identify the location of cirrus formation and the cirrus type: in situ or liquid origin cirrus, depending on whether there is only ice or also liquid water present in the cirrus history, respectively. The cirrus formed and measured at mid-latitudes (M-M) have particularly high ice number concentration and low effective diameter. This is very likely a signature of contrails and contrail cirrus, which is often observed in the in situ origin cirrus type. In contrast, the largest effective diameter and lowest number concentration were found in the cirrus formed and measured at high latitudes (H-H) along with the highest relative humidity over ice (RHi). On average, in-cloud RHi was above saturation in all cirrus. While most of the H-H cirrus were of in situ origin, the cirrus formed at mid-latitudes and measured at high latitudes (M-H) were mainly of liquid origin. A pristine Arctic background atmosphere with scarce availability of ice nuclei and the extended growth of few nucleated ice crystals may explain the observed RHi and size distributions. The M-H cirrus are a mixture of the properties of M-M and H-H cirrus (preserving some of the initial properties acquired at mid-latitudes and transforming under Arctic atmospheric conditions). Our analyses indicate that part of the cirrus found at high latitudes are actually formed at mid-latitudes, and therefore affected by mid-latitude air masses, which have a greater anthropogenic influence.

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Section: Relating Ice Cloud Microphysical Properties To the Location ...mentioning

confidence: 99%

mentioning

confidence: 99%

Differences in microphysical properties of cirrus at high and mid-latitudes

Castro

Jurkat‐Witschas

Afchine³

et al. 2023

Preprint

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“…Wang et al [13] additionally investigated the microphysical properties of satelliteobserved contrails. Their measurements and comparisons of effective radius, particle number density, and optical thickness between contrails, contrail cirrus, and natural cirrus based on in-situ measurements result in smaller particle radii in contrails than in natural cirrus.…”

Section: Introductionmentioning

confidence: 99%

Validation of a Contrail Life-Cycle Model in Central Europe

et al. 2023

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In an industry beset by economic and environmental crises, air transport, the safest and most efficient long-haul mode of transport, is confronted daily with multi-criteria challenges to improve its environmental performance. The formation of contrails through the emission of water vapor and condensation nuclei in what are actually dry and clean atmospheric layers represents one of the most unpredictable, or measurable, environmental impacts of air traffic. Following the bottom-up principle to evaluate individual contrails in order to derive recommendations for trajectory optimization, not only the calculation of the radiative forcing of the contrails but also the modeling of their life cycle is burdened with uncertainties. In former studies for modeling the microphysical life cycle of contrails based on a 3-D Gaussian plume model, the atmospheric conditions, specifically the turbulence, were often unknown and had to be considered as a free input variable. In this study, an innovative photographic method for identifying and tracking contrails in Central Europe, connected with database access to Automatic Dependent Surveillance—Broadcast (ADS-B) data (i.e., aircraft type, speed, altitude, track, etc.), and a combination of measured and modeled weather data are used to validate the contrail life-cycle model (i.e., the assumed Gaussian plume behavior). We found that it is challenging to model the position of ice-supersaturated layers with global forecast models, but they have the most significant impact on the contrail lifetime. On average, the contrail’s lifespan could be modeled with an error margin of 10%. Sometimes, we slightly underestimated the lifetime. With the validated and plausible contrail life-cycle model, we can apply the climate effectiveness of individual contrails with higher certainty in trajectory optimization and compare it, for example, with economic aspects such as delay costs or fuel costs.

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Observations of microphysical properties and radiative effects of contrail cirrus and natural cirrus over the North Atlantic

Cited by 2 publications

References 42 publications

Differences in microphysical properties of cirrus at high and mid-latitudes

Differences in microphysical properties of cirrus at high and mid-latitudes

Validation of a Contrail Life-Cycle Model in Central Europe

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