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Air traffic and contrail changes over Europe during COVID-19: A model study

Schumann, Ulrich and Poll, D. I. A. and Teoh, Roger and Koelle, Rainer and Spinielli, Enrico and Molly, Jarlath and Koudis, George S. and Baumann, Robert and Bugliaro Goggia, Luca and Stettler, Marc E. J. and Voigt, Christiane (2021) Air traffic and contrail changes over Europe during COVID-19: A model study. Atmospheric Chemistry and Physics, 21 (10), pp. 7429-7450. Copernicus Publications. doi: 10.5194/acp-21-7429-2021. ISSN 1680-7316.

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Official URL: https://acp.copernicus.org/articles/21/7429/2021/

Abstract

The strong reduction of air traffic during the COVID-19 pandemic provides a unique test case for the relation between air traffic density, contrails, and their radiative forcing of climate change. Here, air traffic and contrail cirrus changes are quantified for a European domain for March to August 2020 and compared to the same period in 2019. Traffic data show a 72 % reduction in flight distance compared with 2019. This paper investigates the induced contrail changes in a model study. The contrail model results depend on various methodological details as discussed in parameter studies. In the reference case, the reduced traffic caused a reduction in contrail length. The reduction is slightly stronger than expected from the traffic change because the weather conditions in 2020 were less favourable for contrail formation than in 2019. Contrail coverage over Europe with an optical depth larger than 0.1 decreased from 4.6 % in 2019 to 1.4 % in 2020; total cirrus cover amount changed by 28 to 25 %. The reduced contrail coverage caused 70 % less longwave and 73 % less shortwave radiative forcing, but, because of various nonlinearities, only 54 % less net forcing in this case. The methods include recently developed models for performance parameters and soot emissions. The overall propulsion efficiency of the aircraft is about 20 % smaller than estimated in earlier studies, resulting in 3 % fewer contrails. Considerable sensitivity to soot emissions is found highlighting fuel and engine importance. The contrail model includes a new approximate method to account for water vapor exchange between contrails and background air and for radiative forcing changes due to contrail-contrail overlap. The water vapor exchange reduces available ice supersaturation in the atmosphere, which is critical for contrail formation. Contrail-contrail overlap changes the computed radiative forcing considerably. Comparisons to satellite observations are described and discussed in a parallel publication.

Item URL in elib:https://elib.dlr.de/142299/
Document Type:Article
Title:Air traffic and contrail changes over Europe during COVID-19: A model study
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Schumann, UlrichDLR, IPAhttps://orcid.org/0000-0001-5255-6869
Poll, D. I. A.Cranfield University, UKUNSPECIFIED
Teoh, RogerCentre for Transport Studies, Imperial College, London, UKUNSPECIFIED
Koelle, RainerEUROCONTROL, BelgiumUNSPECIFIED
Spinielli, EnricoEUROCONTROL, BelgiumUNSPECIFIED
Molly, JarlathNATS, UKUNSPECIFIED
Koudis, George S.NATS, UKUNSPECIFIED
Baumann, RobertDLR, IPAhttps://orcid.org/0000-0001-6611-5343
Bugliaro Goggia, LucaDLR, IPAhttps://orcid.org/0000-0003-4793-0101
Stettler, Marc E. J.Centre for Transport Studies, Imperial College, London, UKUNSPECIFIED
Voigt, ChristianeDLR, IPAhttps://orcid.org/0000-0001-8925-7731
Date:2021
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:21
DOI :10.5194/acp-21-7429-2021
Page Range:pp. 7429-7450
Publisher:Copernicus Publications
ISSN:1680-7316
Status:Published
Keywords:Contrail COVID-19 cirrus irradiance solar terrestrial traffic performance efficiency Europe model CoCiP
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Air Transportation and Impact
DLR - Research area:Aeronautics
DLR - Program:L AI - Air Transportation and Impact
DLR - Research theme (Project):L - Climate, Weather and Environment, R - Atmospheric and climate research
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics
Institute of Atmospheric Physics > Cloud Physics
Institute of Atmospheric Physics > Atmospheric Trace Species
Deposited By: Schumann, Prof.Dr.habil. Ulrich
Deposited On:19 May 2021 13:07
Last Modified:19 May 2021 13:07

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