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Non-orographic gravity waves and turbulence caused by merging jet streams

Woiwode, Wolfgang and Dörnbrack, Andreas and Geldenhuys, Markus and Friedl-Vallon, F. and Giez, Andreas and Gulde, T. and Höpfner, M. and Johansson, Sören and Kaifler, Bernd and Kleinert, A. and Krasauskas, Lukas and Kretschmer, Erik and Maucher, G. and Neubert, T. and Nordmeyer, H. and Piesch, C. and Preusse, P. and Rapp, Markus and Riese, Martin and Schumann, Ulrich and Ungermann, Jörn (2023) Non-orographic gravity waves and turbulence caused by merging jet streams. Journal of Geophysical Research: Atmospheres, 128 (14), e2022JD038097. Wiley. doi: 10.1029/2022JD038097. ISSN 2169-897X.

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Official URL: https://doi.org/10.1029/2022JD038097

Abstract

Jet streams are important sources of non-orographic internal gravity waves and clear air turbulence (CAT). We analyze non-orographic gravity waves and CAT during a merger of the polar front jet stream (PFJ) with the subtropical jet stream (STJ) above the southern Atlantic. Thereby, we use a novel combination of airborne observations covering the meso-scale and turbulent scale in combination with high-resolution deterministic short-term forecasts. Coherent phase lines of temperature perturbations by gravity waves stretching along a highly sheared tropopause fold are simulated by the ECMWF IFS (integrated forecast system) forecasts. During the merging event, the PFJ reverses its direction from approximately antiparallel to parallel with respect to the STJ, going along with strong wind shear and horizontal deformation. Temperature perturbations in limb-imaging and lidar observations onboard the research aircraft HALO during the SouthTRAC campaign show remarkable agreement with the IFS data. Ten hours earlier, the IFS data show an “X-shaped” pattern in the temperature perturbations emanating from the sheared tropopause fold. Tendencies of the IFS wind components show that these gravity waves are excited by spontaneous emission adjusting the strongly divergent flow when the PFJ impinges the STJ. In situ observations of temperature and wind components at 100 Hz confirm upward propagation of the probed portion of the gravity waves. They furthermore reveal embedded episodes of light-to-moderate CAT, Kelvin Helmholtz waves, and indications for partial wave reflection. Patches of low Richardson numbers in the IFS data coincide with the CAT observations, suggesting that this event was accessible to turbulence forecasting.

Item URL in elib:https://elib.dlr.de/199403/
Document Type:Article
Title:Non-orographic gravity waves and turbulence caused by merging jet streams
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Woiwode, WolfgangKIT, IMK, KarlsruheUNSPECIFIEDUNSPECIFIED
Dörnbrack, AndreasDLR, IPAhttps://orcid.org/0000-0003-0936-0216UNSPECIFIED
Geldenhuys, MarkusForschungszentrum Jülich (IEK-7), Jülich, Germanyhttps://orcid.org/0000-0001-6273-5633UNSPECIFIED
Friedl-Vallon, F.KIT, Karlsruhe, GermanyUNSPECIFIEDUNSPECIFIED
Giez, AndreasUNSPECIFIEDhttps://orcid.org/0000-0002-8595-8343UNSPECIFIED
Gulde, T.Univ. KarlsruheUNSPECIFIEDUNSPECIFIED
Höpfner, M.Univ. KarlsruheUNSPECIFIEDUNSPECIFIED
Johansson, SörenKIT, IMK, KarlsruheUNSPECIFIEDUNSPECIFIED
Kaifler, BerndDLR, IPAhttps://orcid.org/0000-0002-5891-242XUNSPECIFIED
Kleinert, A.KIT, Karlsruhe, GermanyUNSPECIFIEDUNSPECIFIED
Krasauskas, LukasFZ Jülich, JülichUNSPECIFIEDUNSPECIFIED
Kretschmer, ErikKIT, IMK, KarlsruheUNSPECIFIEDUNSPECIFIED
Maucher, G.KIT, Karlsruhe, GermanyUNSPECIFIEDUNSPECIFIED
Neubert, T.Research Centre JülichUNSPECIFIEDUNSPECIFIED
Nordmeyer, H.KIT, Karlsruhe, GermanyUNSPECIFIEDUNSPECIFIED
Piesch, C.Univ. KarlsruheUNSPECIFIEDUNSPECIFIED
Preusse, P.Forschungzentrum Jülich, IEK7, Jülich, GermanyUNSPECIFIEDUNSPECIFIED
Rapp, MarkusDLR, IPAhttps://orcid.org/0000-0003-1508-5900UNSPECIFIED
Riese, MartinForschungszentrum Jülich, (IEK-7), Jülich, Germanyhttps://orcid.org/0000-0001-6398-6493UNSPECIFIED
Schumann, UlrichDLR, IPAhttps://orcid.org/0000-0001-5255-6869UNSPECIFIED
Ungermann, JörnFZ Jülich, IEK7, Jülich, GermanyUNSPECIFIEDUNSPECIFIED
Date:19 July 2023
Journal or Publication Title:Journal of Geophysical Research: Atmospheres
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:128
DOI:10.1029/2022JD038097
Page Range:e2022JD038097
Publisher:Wiley
ISSN:2169-897X
Status:Published
Keywords:gravity waves clear air turbulence jet stream HALO SouthTrac
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Atmospheric and climate research, L - Climate, Weather and Environment
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Transport Meteorology
Institute of Atmospheric Physics > Zentrale Aufgaben PA
Institute of Atmospheric Physics
Flight Experiments > Oberpfaffenhofen
Deposited By: Schumann, Prof.Dr.habil. Ulrich
Deposited On:20 Nov 2023 08:48
Last Modified:04 Dec 2023 11:38

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