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The origin of semidiurnal neutral wind oscillations in the high-latitude ionospheric dynamo region

Günzkofer, Florian Ludwig and Pokhotelov, Dimitry and Stober, G. and Liu, Huixin and Liu, Hanli and Mitchell, N. and Tjulin, Anders and Borries, Claudia (2023) The origin of semidiurnal neutral wind oscillations in the high-latitude ionospheric dynamo region. IUGG General Assembly 2023, Berlin, Deutschland.

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Tidal neutral wind oscillations in the high latitude ionospheric dynamo/transition region can be either in situ forced or propagate there from lower atmospheric layers. Investigating the complex mixing of tidal modes allows to determine the solar, geomagnetic and atmospheric impact on the transition region dynamics. In classical tidal theory, semidiurnal tides forced by UV and infrared absorption in lower atmospheric regions propagate upwards and are the dominant tidal mode up to about 120 km. Above that, diurnal tidal modes forced in situ by EUV absorption and ion drag due to the polar plasma convection are assumed to be dominant. We analyze a 22 day long measurement campaign with the EISCAT UHF incoherent scatter radar during September 2005. The beam-swinging experiment allows to obtain neutral winds from 96 - 142 km altitude which are combined with simultaneous meteor radar measurements. An Adaptive Spectral Filtering technique is applied to determine tidal amplitudes and phases. The zonal wind showed the expected transition from semidiurnal to diurnal oscillations at about 120 km. The meridional wind showed a more complex tidal structuring with dominant 12h oscillations below 110 km and above 130 km. General Circulation Model runs with different forcing settings are analyzed to determine the origin of these high altitude semidiurnal oscillations. The measured asymmetry of tidal amplitudes in zonal and meridional winds is found in all investigated model runs. It is shown that atmospheric tides have no influence on tidal oscillations above 120 km. Polar ion convection and EUV absorption both appear to contribute to the observed strong semidiurnal oscillations above 130 km.

Item URL in elib:https://elib.dlr.de/196096/
Document Type:Conference or Workshop Item (Speech)
Title:The origin of semidiurnal neutral wind oscillations in the high-latitude ionospheric dynamo region
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Günzkofer, Florian LudwigUNSPECIFIEDhttps://orcid.org/0000-0001-6568-2995UNSPECIFIED
Pokhotelov, DimitryUNSPECIFIEDhttps://orcid.org/0000-0002-3712-0597UNSPECIFIED
Stober, G.UNSPECIFIEDhttps://orcid.org/0000-0002-7909-6345UNSPECIFIED
Liu, HuixinUNSPECIFIEDhttps://orcid.org/0000-0001-7073-4366UNSPECIFIED
Tjulin, AndersEISCAT Scientific AssociationUNSPECIFIEDUNSPECIFIED
Borries, ClaudiaUNSPECIFIEDhttps://orcid.org/0000-0001-9948-3353UNSPECIFIED
Date:July 2023
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:ionospheric dynamo region, tidal neutral wind oscillations, incohrerent scatter radar
Event Title:IUGG General Assembly 2023
Event Location:Berlin, Deutschland
Event Type:international Conference
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 - Solar-Terrestrial coupling processes
Location: Neustrelitz
Institutes and Institutions:Institute for Solar-Terrestrial Physics > Solar-Terrestrial Coupling Processes
Deposited By: Günzkofer, Florian Ludwig
Deposited On:22 Aug 2023 17:34
Last Modified:22 Aug 2023 17:34

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