Satellite Observations of the Impact of Individual Aircraft on Ice Crystal Number in Thin Cirrus Clouds

Marjani, Sajedeh; Tesche, Matthias; Bräuer, Peter; Sourdeval, Odran; Quaas, Johannes

doi:10.1029/2021gl096173

Cited by 7 publications

(5 citation statements)

References 57 publications

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“…We apply multiplication factors of 0.1, 0.5, 0.9, 1.1, 1.25, 1.5, 2 and 10 to explore a wide range of possible aviation perturbations. The ICNC×1.25, ×1.5 experiments are closest to the satellite-based estimates of Marjani et al (2022), while the ICNC×0.5 and ×2 experiments represent large but still-plausible perturbations. The ICNC×0.1 and ×10 perturbations are unrealistic, but useful to study the degree of linearity in ice water response.…”

Section: Idealised Perturbationsmentioning

confidence: 64%

“…The perturbations induced are intended to be plausible. For example, we apply ICNC perturbations of 25% and 50%, which are comparable to the results of Marjani et al (2022).…”

mentioning

confidence: 67%

“…For example, Tesche et al (2016) use satellite cloud retrievals to suggest passing aircraft increase cirrus cloud optical depth. Marjani et al (2022) developed the method of Tesche et al (2016) to show that ICNC increases in the areas immediately behind, adjacent to and below an aircraft's flight path by 25 -54%. They explore the effects only on thin, mainly in situ origin cirrus, defined as those clouds with geometrical thickness smaller than 2 km.…”

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confidence: 99%

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Response of cirrus clouds to idealised perturbations from aviation

Gilbert,

Purseed,

et al. 2024

Preprint

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Abstract. Aviation is a rapidly growing source of climate forcing, and the non-CO2 effective radiative forcing of aviation is approximately twice that of aviation CO2. However, considerable uncertainty remains regarding aviation’s non-CO2 effects because the radiative forcing of aviation aerosol-cloud interactions, especially with cirrus clouds, is poorly known. Here, we use a large eddy simulation model to quantify the impact of ice crystal number concentration (ICNC) perturbations on the water budget and microphysics of pre-existing cirrus clouds. These perturbations aim to represent the second half of the chain of effects linking aircraft aerosol emissions to changes in ICNC and ice water path. We examine two types of cirrus: warm conveyor belt outflow and gravity wave cirrus, which represent different updraft regimes and formation mechanisms. In both cases, the primary effect of an idealised increase in ICNC is to extend cloud lifetime, with the increase proportional to the magnitude of the ICNC perturbation applied. The effect is more pronounced in the gravity wave cirrus case than in the warm conveyor belt outflow cirrus case because the latter has lower initial ICNC and ice water contents. Quantitatively, the sensitivity of ice water path (IWP) to changes in ICNC, expressed as ∆ln(IWP)/∆ln(ICNC), is 0.06 for gravity wave cirrus and 0.35 for warm conveyor belt outflow cirrus when calculated 45 minutes after imposing the ICNC perturbation. These results suggest that aviation has the potential to increase the lifetime and radiative effects of pre-existing cirrus clouds.

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Section: Idealised Perturbationsmentioning

confidence: 64%

“…The perturbations induced are intended to be plausible. For example, we apply ICNC perturbations of 25% and 50%, which are comparable to the results of Marjani et al (2022).…”

mentioning

confidence: 67%

mentioning

confidence: 99%

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Response of cirrus clouds to idealised perturbations from aviation

Gilbert,

Purseed,

et al. 2024

Preprint

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“…Using the advected flightpaths to identify potential aircraft-modified clouds (e.g. Tesche et al 2016, Duda et al 2019, Marjani et al 2022, Chevallier et al 2023 avoids the requirement for tracking COs and potential selection biases associated with the filtering and tracking processes. Although the CNN produces a considerable number of false positives (figure 3(a)), these are significantly reduced over the ocean.…”

Section: Fleet-wide Contrailsmentioning

confidence: 99%

Operational differences lead to longer lifetimes of satellite detectable contrails from more fuel efficient aircraft

Gryspeerdt,

Stettler,

Teoh

et al. 2024

Environ. Res. Lett.

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Clouds produced by aircraft (known as contrails) contribute over half of the positive radiative forcing from aviation, but the size of this warming effect is highly uncertain. Their radiative effect is highly dependent on the microphysical properties and meteorological background state, varying strongly over the contrail lifecycle. In-situ observations have demonstrated an impact of aircraft and fuel type on contrail properties close to the aircraft, but there are few observational constraints at these longer timescales, despite these having a strong impact in high-resolution and global models. This work provides an observational quantification of these contrail controlling factors, matching air traffic data to satellite observations of contrails to isolate the role of the aircraft type in contrail properties and evolution. Investigating over 64 000 cases, a relationship between aircraft type and contrail formation is observed, with more efficient aircraft forming longer-lived satellite-detectable contrails more frequently, which could lead to a larger climate impact. This increase in contrail formation and lifetime is primarily driven by an increase in flight altitude. Business jets are also found to produce longer-lived satellite-detectable contrails despite their lower fuel flow, as they fly at higher altitudes. The increase in satellite-detected contrails behind more efficient aircraft suggests a trade-off between aircraft greenhouse gas emissions and the aviation climate impact through contrail production, due to differences in aircraft operation.

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“…Following the same methodology, Marjani et al (2022) focused on the number concentration and found an increase within a few hundred meters behind the aircraft and below its flight track. In line with airborne observations, Verma and Burkhardt (2022) simulated contrail formation within pre-existing cirrus and found that contrails increased the ice crystal number concentration of cirrus by a few orders of magnitude.…”

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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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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Satellite Observations of the Impact of Individual Aircraft on Ice Crystal Number in Thin Cirrus Clouds

Cited by 7 publications

References 57 publications

Response of cirrus clouds to idealised perturbations from aviation

Response of cirrus clouds to idealised perturbations from aviation

Operational differences lead to longer lifetimes of satellite detectable contrails from more fuel efficient aircraft

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

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