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Diabatic generation of negative potential vorticity and its impact on the North Atlantic jet stream

Harvey, Ben und Methven, John und Sanchez, Claudio und Schäfler, Andreas (2020) Diabatic generation of negative potential vorticity and its impact on the North Atlantic jet stream. Quarterly Journal of the Royal Meteorological Society, Seiten 1477-1497. Wiley. doi: 10.1002/qj.3747. ISSN 0035-9009.

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Offizielle URL: https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/qj.3747

Kurzfassung

Localised regions of negative potential vorticity (PV) are frequently seen on the equatorward flank of the upper‐tropospheric jet streams in analysis and forecast products. Their positioning, on the anticyclonic side of the jet and often close to the jet core, suggest they are associated with an enhancement of jet stream maximum winds. Given that PV is generally positive in the northern hemisphere and is materially conserved under adiabatic conditions, the presence of negative PV is indicative of recent diabatic activity. However, little is understood on the mechanisms for its generation and subsequent impacts. In this paper, aircraft measurements from a recent field campaign are used to provide direct observational evidence for the presence of negative PV on the anticyclonic side of an upper‐tropospheric jet. Theory is then developed to understand the process by which PV can turn negative. The key ingredient is diabatic heating in the presence of vertical wind shear, and the resulting PV anomalies are shown to always result from a flux of PV directed “down the isentropic slope”. This explains why, for the typical situation of heating in a warm conveyor belt, negative PV values appear on the equatorward side of the upper‐tropospheric jet stream close to the jet core. These ideas are illustrated with a semi‐geostrophic model and the processes responsible for the observed negative PV are explored using an operational forecast model with online PV tracer diagnostics. The diabatic influence on jet stream winds and shear is of interest because it is pertinent to the predictability of extreme jet stream events and associated flight‐level turbulence, and is crucial to the propagation of Rossby waves at tropopause level, development of midlatitude weather systems and their subsequent impacts at the surface.

elib-URL des Eintrags:https://elib.dlr.de/134895/
Dokumentart:Zeitschriftenbeitrag
Titel:Diabatic generation of negative potential vorticity and its impact on the North Atlantic jet stream
Autoren:
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID-iDORCID Put Code
Harvey, BenUniv. of Reading, UKNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Methven, JohnUniv. of Reading, UKNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Sanchez, ClaudioMet Office, UKNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Schäfler, AndreasDLR, IPAhttps://orcid.org/0000-0002-6165-6623NICHT SPEZIFIZIERT
Datum:21 Februar 2020
Erschienen in:Quarterly Journal of the Royal Meteorological Society
Referierte Publikation:Ja
Open Access:Nein
Gold Open Access:Nein
In SCOPUS:Ja
In ISI Web of Science:Ja
DOI:10.1002/qj.3747
Seitenbereich:Seiten 1477-1497
Verlag:Wiley
ISSN:0035-9009
Status:veröffentlicht
Stichwörter:NAWDEX, observations, warm conveyor belt, Rossby waves
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Raumfahrt
HGF - Programmthema:Erdbeobachtung
DLR - Schwerpunkt:Raumfahrt
DLR - Forschungsgebiet:R EO - Erdbeobachtung
DLR - Teilgebiet (Projekt, Vorhaben):R - LIDAR-Forschung und - Entwicklung
Standort: Oberpfaffenhofen
Institute & Einrichtungen:Institut für Physik der Atmosphäre
Institut für Physik der Atmosphäre > Lidar
Hinterlegt von: Schäfler, Andreas
Hinterlegt am:13 Mai 2020 12:23
Letzte Änderung:13 Mai 2020 12:23

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