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Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing

Kärcher, Bernd und Burkhardt, Ulrike und Ponater, Michael und Frömming, Christine (2010) Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing. Proceedings of the National Academy of Science (PNAS), 45, Seiten 19181-19184. DOI: 10.1073/pnas.1005555107.

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Offizielle URL: http://www.pnas.org/content/107/45/19181.full.pdf+html

Kurzfassung

Estimates of the global radiative forcing by line-shaped contrails differ mainly due to the large uncertainty in contrail optical depth. Most contrails are optically thin so that their radiative forcing is roughly proportional to their optical depth and increases with contrail coverage. In recent assessments, the best estimate of mean contrail radiative forcing was significantly reduced, because global climate model simulations pointed at lower optical depth values than earlier studies. We revise these estimates by comparing the probability distribution of contrail optical depth diagnosed with a climate model with the distribution derived from a microphysical, cloud-scale model constrained by satellite observations over the United States. By assuming that the optical depth distribution from the cloud model is more realistic than that from the climate model, and by taking the difference between the observed and simulated optical depth over the United States as globally representative, we quantify uncertainties in the climate model’s diagnostic contrail parameterization. Revising the climate model results accordingly increases the global mean radiative forcing estimate for line-shaped contrails by a factor of 3.3, from 3.5 mW∕m2 to 11.6 mW∕m2 for the year 1992. Furthermore, the satellite observations and the cloud model point at higher global mean optical depth of detectable contrails than often assumed in radiative transfer (off-line) studies. Therefore, we correct estimates of contrail radiative forcing from off-line studies as well. We suggest that the global net radiative forcing of line-shaped persistent contrails is in the range 8–20 mW∕m2 for the air traffic in the year 2000.

Dokumentart:Zeitschriftenbeitrag
Titel:Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Kärcher, BerndNICHT SPEZIFIZIERT
Burkhardt, UlrikeNICHT SPEZIFIZIERT
Ponater, MichaelNICHT SPEZIFIZIERT
Frömming, ChristineNICHT SPEZIFIZIERT
Datum:9 November 2010
Erschienen in:Proceedings of the National Academy of Science (PNAS)
Referierte Publikation:Ja
In Open Access:Nein
In SCOPUS:Ja
In ISI Web of Science:Ja
Band:45
DOI :10.1073/pnas.1005555107
Seitenbereich:Seiten 19181-19184
Status:veröffentlicht
Stichwörter:aviation, contrails, radiative forcing
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Luftfahrt
HGF - Programmthema:L VU - Luftverkehr und Umwelt (alt)
DLR - Schwerpunkt:Luftfahrt
DLR - Forschungsgebiet:L VU - Luftverkehr und Umwelt
DLR - Teilgebiet (Projekt, Vorhaben):L - Schadstoffarmer Luftverkehr (alt)
Standort: Oberpfaffenhofen
Institute & Einrichtungen:Institut für Physik der Atmosphäre > Atmosphärische Spurenstoffe
Hinterlegt von: Prof. Bernd Kärcher
Hinterlegt am:06 Dez 2010 14:58
Letzte Änderung:12 Dez 2013 21:06

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