The importance of the diurnal and annual cycle of air traffic for contrail radiative forcing

Stuber, N.; Forster, Piers M.; Rädel, G.; Shine, Keith P.

doi:10.1038/nature04877

Cited by 94 publications

(78 citation statements)

References 24 publications

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“…Radiative transfer studies of contrails with assumed properties (Myhre and Stordal, 2001;Stuber et al, 2006;Stuber and Forster, 2007) indicate that contrails contribute more to radiative forcing of climate during nighttime than during daytime although flights spend on average more time during day than during night. It might be that the degree of the day/night differences is actually smaller than computed in the pure radiative transfer studies.…”

Section: Discussionmentioning

confidence: 99%

Numerical simulations of contrail-to-cirrus transition – Part 2: Impact of initial ice crystal number, radiation, stratification, secondary nucleation and layer depth

Unterstraßer

Gierens

2010

Atmos. Chem. Phys.

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Abstract.Simulations of contrail-to-cirrus transition were performed with an LES model. In Part 1 the impact of relative humidity, temperature and vertical wind shear was explored in a detailed parametric study. Here, we study atmospheric parameters like stratification and depth of the supersaturated layer and processes which may affect the contrail evolution. We consider contrails in various radiation scenarios herein defined by the season, time of day and the presence of lower-level cloudiness which controls the radiance incident on the contrail layer. Under suitable conditions, controlled by the radiation scenario and stratification, radiative heating lifts the contrail-cirrus and prolongs its lifetime. The potential of contrail-driven secondary nucleation is investigated. We consider homogeneous nucleation and heterogeneous nucleation of preactivated soot cores released from sublimated contrail ice crystals. In our model the contrail dynamics triggered by radiative heating does not suffice to force homogeneous freezing of ambient liquid aerosol particles. Furthermore, our model results suggest that heterogeneous nucleation of preactivated soot cores is unimportant. Contrail evolution is not controlled by the depth of the supersaturated layer as long as it exceeds roughly 500 m. Deep fallstreaks however need thicker layers. A variation of the initial ice crystal number is effective during the whole evolution of a contrail. A cut of the soot particle emission by two orders of magnitude can reduce the contrail timescale by one hour and the optical thickness by a factor of 5. Hence future engines with lower soot particle emissions could potentially lead to a reduction of the climate impact of aviation.

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Section: Discussionmentioning

confidence: 99%

Numerical simulations of contrail-to-cirrus transition – Part 2: Impact of initial ice crystal number, radiation, stratification, secondary nucleation and layer depth

Unterstraßer

Gierens

2010

Atmos. Chem. Phys.

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“…Stuber et al (2006) investigated the effects of diurnal variations of air traffic on contrail radiative forcing over south-east England. They found that flights during the night time have a disproportionate effect on the annual, diurnal mean contrail radiative forcing.…”

Section: Introductionmentioning

confidence: 99%

“…To determine the impact of diurnal variations of air traffic on global mean contrail radiative forcing, and to see how far the results of Stuber et al (2006) are applicable to other regions and the globe, we performed a global calculation of the radiative forcing due to line-shaped contrails. We derived contrail cover from a combination of diurnally resolved air traffic data, and ECMWF analysis data.…”

Section: Introductionmentioning

confidence: 99%

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The impact of diurnal variations of air traffic on contrail radiative forcing

Stuber

Forster

2007

Atmos. Chem. Phys.

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Abstract. We combined high resolution aircraft flight data from the EU Fifth Framework Programme project AERO2k with analysis data from the ECMWF's integrated forecast system to calculate diurnally resolved 3-D contrail cover. We scaled the contrail cover in order to match observational data for the Bakan area (eastern-Atlantic/western-Europe).We found that less than 40% of the global distance travelled by aircraft is due to flights during local night time. Yet, due to the cancellation of shortwave and longwave effects during daytime, night time flights contribute a disproportional 60% to the global annual mean forcing. Under clear sky conditions the night flights contribute even more disproportionally at 76%. There are pronounced regional variations in night flying and the associated radiative forcing. Over parts of the North Atlantic flight corridor 75% of air traffic and 84% of the forcing occurs during local night, whereas only 35% of flights are during local night in South-East Asia, yet these contribute 68% of the radiative forcing. In general, regions with a significant local contrail radiative forcing are also regions for which night time flights amount to less than half of the daily total of flights. Therefore, neglecting diurnal variations in air traffic/contrail cover by assuming a diurnal mean contrail cover can over-estimate the global mean radiative forcing by up to 30%.

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“…The mean annual radiative forcing estimate, e.g. for the specific location Herstmonceux (Stuber et al, 2006) is 0.75 W m −2 in the long wavelength range and −0.5 W m −2 in the short wavelength range which amounts to a total radiative forcing of around 0.25 W m −2 . Minnis et al (2004) showed that 85 % of the days with persistent contrails are also days with cirrus cloudiness.…”

Section: Introductionmentioning

confidence: 99%

Potential impact of contrails on solar energy gain

et al. 2015

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Abstract. The effect of contrails on global short-wave radiation (sum of direct and downward diffuse solar radiation) and on solar energy gain was investigated. The study was performed during days with high contrail persistence and focused on situations where the contrails were obstructing the sun. Measurements of cloudiness using a fish-eye camera, diffuse and direct short-wave measurements and measurements of the short circuit current of three different types of photovoltaic (PV) modules were performed at the Kanzelhöhe Observatory (1540 m a.s.l.) with a time resolution of 1 min over a period of 1 year. The results show that contrails moving between sun and observer/sensor may reduce the global radiation by up to 72 %. An analysis of contrail persistence and the influence of contrails on global irradiance and solar energy gain is presented. The losses in solar energy gain that were recorded may be critical under specific circumstances.

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The importance of the diurnal and annual cycle of air traffic for contrail radiative forcing

Cited by 94 publications

References 24 publications

Numerical simulations of contrail-to-cirrus transition – Part 2: Impact of initial ice crystal number, radiation, stratification, secondary nucleation and layer depth

Numerical simulations of contrail-to-cirrus transition – Part 2: Impact of initial ice crystal number, radiation, stratification, secondary nucleation and layer depth

The impact of diurnal variations of air traffic on contrail radiative forcing

Potential impact of contrails on solar energy gain

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