Simulated 2050 aviation radiative forcing from contrails and aerosols

Chen, Celia; Gettelman, Andrew

doi:10.5194/acp-16-7317-2016

Cited by 26 publications

(28 citation statements)

References 43 publications

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“…Asterisks mark extrapolated values calculated with the factor resulting from the radiative forcing in 2006 associated with air traffic volume using slant distance and track distance (Bock and Burkhardt, 2016b Pathway 6.0; RCP6.0.) (Chen et al, 2012). The radiation scheme is called every half hour calculating radiative transfer with and without contrail cirrus (see Bock and Burkhardt, 2016b, for details).…”

Section: Simulation Setupmentioning

confidence: 99%

Contrail cirrus radiative forcing for future air traffic

Bock

Burkhardt

2019

Atmos. Chem. Phys.

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The climate impact of air traffic is to a large degree caused by changes in cirrus cloudiness resulting from the formation of contrails. Contrail cirrus radiative forcing is expected to increase significantly over time due to the large projected increases in air traffic. We use ECHAM5-CCMod, an atmospheric climate model with an online contrail cirrus parameterization including a microphysical two-moment scheme, to investigate the climate impact of contrail cirrus for the year 2050. We take into account the predicted increase in air traffic volume, changes in propulsion efficiency and emissions, in particular soot emissions, and the modification of the contrail cirrus climate impact due to anthropogenic climate change.Global contrail cirrus radiative forcing increases by a factor of 3 from 2006 to 2050, reaching 160 or even 180 mW m −2 , which is the result of the increase in air traffic volume and a slight shift in air traffic towards higher altitudes. Large increases in contrail cirrus radiative forcing are expected over all of the main air traffic areas, but relative increases are largest over main air traffic areas over eastern Asia. The projected upward shift in air traffic attenuates contrail cirrus radiative forcing increases in the midlatitudes but reinforces it in the tropical areas. Climate change has an insignificant impact on global contrail cirrus radiative forcing, while regional changes are significant. Of the emission reductions it is the soot number emission reductions by 50 % that lead to a significant decrease in contrail cirrus optical depth and coverage, leading to a decrease in radiative forcing by approximately 15 %. The strong increase in contrail cirrus radiative forcing due to the projected increase in air traffic volume cannot be compensated for by the decrease in initial ice crystal numbers due to reduced soot emissions and improvements in propulsion efficiency.Published by Copernicus Publications on behalf of the European Geosciences Union.

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Section: Simulation Setupmentioning

confidence: 99%

Contrail cirrus radiative forcing for future air traffic

Bock

Burkhardt

2019

Atmos. Chem. Phys.

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“…An explanation of this pattern requires a more detailed study. Such a study should include different absorption by optically thin clouds with different particle sizes (Inoue, 1985), wind-driven or convective uplift possibly causing pileus clouds (Garrett et al, 2006), presence of nitric acid, which has an 11 µm absorption band (Chepfer et al, 2007), the satellite viewing angles, and threedimensional radiation transfer. Figure 16.…”

Section: Noaa-avhrr Satellite Observations Above Hectormentioning

confidence: 99%

Long-lived contrails and convective cirrus above the tropical tropopause

et al. 2017

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This study has two objectives: (1) it characterizes contrails at very low temperatures and (2) it discusses convective cirrus in which the contrails occurred. (1) Long-lived contrails and cirrus from overshooting convection are investigated above the tropical tropopause at low temperatures down to −88 °C from measurements with the Russian high-altitude research aircraft M-55 "Geophysica", as well as related observations during the SCOUT-O3 field experiment near Darwin, Australia, in 2005. A contrail was observed to persist below ice saturation at low temperatures and low turbulence in the stratosphere for nearly 1 h. The contrail occurred downwind of the decaying convective system "Hector" of 16 November 2005. The upper part of the contrail formed at 19 km altitude in the tropical lower stratosphere at ∼ 60 % relative humidity over ice at −82 °C. The ∼ 1 h lifetime is explained by engine water emissions, slightly enhanced humidity from Hector, low temperature, low turbulence, and possibly nitric acid hydrate formation. The long persistence suggests large contrail coverage in case of a potential future increase of air traffic in the lower stratosphere. (2) Cirrus observed above the strongly convective Hector cloud on 30 November 2005 was previously interpreted as cirrus from overshooting convection. Here we show that parts of the cirrus were caused by contrails or are mixtures of convective and contrail cirrus. The in situ data together with data from an upward-looking lidar on the German research aircraft "Falcon", the CPOL radar near Darwin, and NOAA-AVHRR satellites provide a sufficiently complete picture to distinguish between contrail and convective cirrus parts. Plume positions are estimated based on measured or analyzed wind and parameterized wake vortex descent. Most of the non-volatile aerosol measured over Hector is traceable to aircraft emissions. Exhaust emission indices are derived from a self-match experiment of the Geophysica in the polar stratosphere in 2010. The number of ice particles in the contrails is less than 1 % of the number of non-volatile aerosol particles, possibly because of sublimation losses and undetected very small ice particles. The radar data show that the ice water content in convective overshoots is far higher than measured along the flight path. These findings add insight into overshooting convection and are of relevance with respect to hydration of the lower stratosphere

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“…The long-term climate impact is mainly driven by CO 2 emissions. Modelling studies have shown that the direct radiative forcing from aviation is expected to represent 3-4 % (50-60 mW m −2 ) of the anthropogenic forcing (Lee et al, 2010;De León et al, 2012) and could reach 87 mW m −2 in 2025 (Chen and Gettelman, 2016). Aircraft-induced cloudiness also has an important impact on climate, although the quantitative assessment 9804 A.…”

Section: Introductionmentioning

confidence: 99%