Contrail radiative forcing over the Northern Hemisphere from 2006 Aqua MODIS data

Spangenberg, Douglas A.; Minnis, Patrick; Bedka, Sarah T.; Palikonda, Rabindra; Duda, David P.

doi:10.1002/grl.50168

Cited by 33 publications

(53 citation statements)

References 29 publications

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“…The computed RF values are far larger than those estimated previously for linear contrails Rap et al, 2010b;Frömming et al, 2011;Yi et al, 2012;Chen and Gettelman, 2013;Spangenberg et al, 2013), 5 times larger than the value estimated for contrail cirrus for the same traffic by Chen and Gettelman (2013), and nearly double the value estimated with a global contrail cirrus model for traffic in the year 2002 by Burkhardt and Kärcher (2011). As indicated, some of the comparisons point to possible overestimates of contrail cover and optical thickness by CoCiP.…”

Section: Some Global Contrail Propertiesmentioning

confidence: 49%

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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Section: Some Global Contrail Propertiesmentioning

confidence: 49%

Dehydration effects from contrails in a coupled contrail–climate model

et al. 2015

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“…Another concern for aviation impacts is the effect of contrails forming in extant cirrus. While contrails will not increase the cirrus coverage when they form within existing cirrus clouds, they can potentially increase the optical depth of those clouds [e.g., Schumann and Graf , ] and have a measurable radiative forcing impact [ Spangenberg et al ., ]. The differences between τ CC and τ Con are consistent with a thickening of cirrus by linear contrails, if it is assumed that the CC constitutes existing cirrus clouds.…”

Section: Resultsmentioning

confidence: 99%

Linear contrail and contrail cirrus properties determined from satellite data

Minnis

Bedka

Duda

et al. 2013

Geophysical Research Letters

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[1] The properties of contrail cirrus clouds are retrieved through analysis of Terra and Aqua Moderate Resolution Imaging Spectroradiometer data for 21 cases of spreading linear contrails. For these cases, contrail cirrus enhanced the linear contrail coverage by factors of 2.4-7.6 depending on the contrail mask sensitivity. In dense air traffic areas, linear contrail detection sensitivity is apparently reduced when older contrails overlap and thus is likely diminished during the afternoon. The mean optical depths and effective particle sizes of the contrail cirrus were 2-3 times and 20% greater, respectively, than the corresponding values retrieved for the adjacent linear contrails. When contrails form below, in, or above existing cirrus clouds, the column cloud optical depth is increased and particle size is decreased. Thus, even without increased cirrus coverage, contrails will affect the radiation balance. These results should be valuable for refining model characterizations of contrail cirrus needed to fully assess the climate impacts of contrails. Citation: Minnis, P., S.

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“…The assessment of the contrail radiative forcing requires, in particular, an accurate estimation of the cloud cover, the visible optical depth, the single-scattering characteristics, and the ice crystal effective size and habit Spangenberg et al, 2013). Satellite observations provide a comprehensive dataset to study the contrail to cirrus evolution statistically.…”

Section: Optical and Microphysical Properties Of Contrail Phasesmentioning

confidence: 99%