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Performance of two GCM borne radiation schemes in calculating contrail radiative forcing

Ponater, Michael und Frömming, Christine (2012) Performance of two GCM borne radiation schemes in calculating contrail radiative forcing. 3rd conference on Transport, Atmosphere, and Climate (TA3-3), 25-28 Jun 2012, Prien am Chiemsee, Germany.

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Kurzfassung

Contrail radiative forcing is difficult to determine even if the numerous key parameters like coverage, ice water content, crystal size etc. are known. One reason is the considerable amount of cancellation between the positive (warming) component from the contrails' greenhouse effect and the negative (cooling) component from backscattering of solar irradiance. This sets high demands on the abilities of the radiative transfer model used to calculate the forcing, and a substantial respective uncertainty has been documented in literature. To complicate things further, the longwave/shortwave cancellation depends on some ambient parameters like ambient temperature, co-existing natural clouds, surface albedo and some others. Climate models are optimally suited to provide a representation of the required variety of ambient parameters for a climatological estimate of contrail radiative forcing. However, comprehensive global climate models have to use simplified radiative transfer schemes for reasons of computational economy. Hence, a dedicated test of these schemes is always indicated. We present a comparison of contrail radiative forcing between two contrail radiative forcing estimates from global climate models. The first is yielded with the ECHAM4 model frequently used for this purpose over the last ten years, the second by the more recent ECHAM5/EMAC model to be applied in the coming years. Use is made of the so-called "Myhre benchmark test" with specified contrail parameters. The ratio of longwave/shortwave cancellation for various seasons and the daytime/nighttime difference are features of particular focus. Contrail radiative forcing is difficult to determine even if the numerous key parameters like coverage, ice water content, crystal size etc. are known. One reason is the high degree of cancellation between the positive (warming) component from the contrails' greenhouse effect and the negative (cooling) component from backscattering of solar irradiance. This sets high demands on the abilities of the radiative transfer model, and a considerable uncertainty of respective calculations has been documented in literature. Furthermore, the longwave/shortwave cancellation is sensitive to several ambient parameters like temperature, co-existing natural clouds, and surface albedo.

Dokumentart:Konferenzbeitrag (Poster)
Titel:Performance of two GCM borne radiation schemes in calculating contrail radiative forcing
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Ponater, MichaelNICHT SPEZIFIZIERT
Frömming, ChristineNICHT SPEZIFIZIERT
Datum:26 Juni 2012
Status:veröffentlicht
Stichwörter:contrail, radiative forcing, longwave radiative flux, shortwave radiative flux
Veranstaltungstitel:3rd conference on Transport, Atmosphere, and Climate (TA3-3)
Veranstaltungsort:Prien am Chiemsee, Germany
Veranstaltungsart:internationale Konferenz
Veranstaltungsdatum:25-28 Jun 2012
Veranstalter :DLR
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Luftfahrt
HGF - Programmthema:ATM und Flugbetrieb
DLR - Schwerpunkt:Luftfahrt
DLR - Forschungsgebiet:L AO - Luftverkehrsmanagement und Flugbetrieb
DLR - Teilgebiet (Projekt, Vorhaben):L - Klima, Wetter und Umwelt
Standort: Oberpfaffenhofen
Institute & Einrichtungen:Institut für Physik der Atmosphäre
Institut für Physik der Atmosphäre > Dynamik der Atmosphäre
Hinterlegt von: Dr.rer.nat. Michael Ponater
Hinterlegt am:08 Okt 2012 16:19
Letzte Änderung:08 Okt 2012 16:19

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