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Downward Control from Lower Stratosphere?

Egger, Joseph und Hoinka, Klaus-Peter (2005) Downward Control from Lower Stratosphere? Journal of the Atmospheric Sciences, 62, Seiten 3808-3817. DOI: 10.1175/JAS3569.1

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The concept of downward control proposes a mechanism for the impact of the stratospheric circulation on the troposphere. Momentum forcing at upper-stratospheric levels induces a meridional circulation that eventually reaches the surface. So far, a lack of sufficiently accurate data hindered an observational test of this downward propagation. The concept is extended in this paper by looking at the effect of angular momentum forcing in prescribed regions in the lower stratosphere on the tropospheric circulation. In that case, the European Centre for Medium-Range Weather Forecasts Reanalysis Project (ERA) data can be used to investigate the atmospheric response to forcing in a prescribed domain. It is found that these forcing events are quite short lived and that angular momentum flux convergence in the prescribed domain is highly correlated with convergence outside this forcing area. Typically, these fields of convergence and also divergence extend to the surface in a quasibarotropic manner outside the Tropics. This structure of the forcing is not compatible with the assumptions of the downward control concept. The observed related meridional circulation therefore differs widely from that predicted. In particular, there is no obvious descent of the circulation to the ground. Even so, such forcing events are accompanied by an intensive exchange of angular momentum between stratosphere and troposphere. The confinement of the forcing to the selected forcing domain is reasonably strict in the Tropics. A relatively narrow tongue of angular momentum is growing at the equator underneath the forcing area. Frictional torques play a role in this development. Altogether, the forcing events as selected involve a strong angular momentum exchange between stratosphere and troposphere but are not suited for a test of the downward control concept. Alternatives are discussed.

Titel:Downward Control from Lower Stratosphere?
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID
Egger, JosephUniv. München, MünchenNICHT SPEZIFIZIERT
Erschienen in:Journal of the Atmospheric Sciences
Referierte Publikation:Ja
In Open Access:Nein
In ISI Web of Science:Ja
DOI :10.1175/JAS3569.1
Seitenbereich:Seiten 3808-3817
Stichwörter:stratosphere, troposphere, ERA40
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W EO - Erdbeobachtung
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W EO - Erdbeobachtung
DLR - Teilgebiet (Projekt, Vorhaben):W - Vorhaben Atmosphären- und Klimaforschung (alt)
Standort: Oberpfaffenhofen
Institute & Einrichtungen:Institut für Physik der Atmosphäre > Wolkenphysik und Verkehrsmeteorologie
Hinterlegt von: Freund, Jana
Hinterlegt am:08 Dez 2006
Letzte Änderung:11 Nov 2014 21:56

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