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Arecibo measurements of D-region electron densities during sunset and sunrise: implications for atmospheric composition

Baumann, Carsten and Kero, Antti and Raizada, Shikha and Rapp, Markus and Sulzer, Michael P. and Verronen, Pekka T. and Vierinen, Juha (2022) Arecibo measurements of D-region electron densities during sunset and sunrise: implications for atmospheric composition. Annales Geophysicae, 40 (4), pp. 519-530. Copernicus Publications. doi: 10.5194/angeo-40-519-2022. ISSN 0992-7689.

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Official URL: https://dx.doi.org/10.5194/angeo-40-519-2022


Earth's lower ionosphere is the region where terrestrial weather and space weather come together. Here, between 60 and 100 km altitude, solar radiation governs the diurnal cycle of the ionized species. This altitude range is also the place where nanometre-sized dust particles, recondensed from ablated meteoric material, exist and interact with free electrons and ions of the ionosphere. This study reports electron density measurements from the Arecibo incoherent-scatter radar being performed during sunset and sunrise conditions. An asymmetry of the electron density is observed, with higher electron density during sunset than during sunrise. This asymmetry extends from solar zenith angles (SZAs) of 80 to 100°. This D-region asymmetry can be observed between 95 and 75 km altitude. The electron density observations are compared to the one-dimensional Sodankylä Ion and Neutral Chemistry (SIC) model and a variant of the Whole Atmosphere Community Climate Model incorporating a subset SIC's ion chemistry (WACCM-D). Both models also show a D-region sunrise–sunset asymmetry. However, WACCM-D compares slightly better to the observations than SIC, especially during sunset, when the electron density gradually fades away. An investigation of the electron density continuity equation reveals a higher electron–ion recombination rate than the fading ionization rate during sunset. The recombination reactions are not fast enough to closely match the fading ionization rate during sunset, resulting in excess electron density. At lower altitudes electron attachment to neutrals and their detachment from negative ions play a significant role in the asymmetry as well. A comparison of a specific SIC version incorporating meteoric smoke particles (MSPs) to the observations revealed no sudden changes in electron density as predicted by the model. However, the expected electron density jump (drop) during sunrise (sunset) occurs at 100° SZA when the radar signal is close to the noise floor, making a clear falsification of MSPs' influence on the D region impossible.

Item URL in elib:https://elib.dlr.de/187814/
Document Type:Article
Title:Arecibo measurements of D-region electron densities during sunset and sunrise: implications for atmospheric composition
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Baumann, CarstenDLR, Neustrelitzhttps://orcid.org/0000-0001-7104-5992UNSPECIFIED
Kero, AnttiUniversity of Oulo, Sodankylä, FinlandUNSPECIFIEDUNSPECIFIED
Raizada, ShikhaArecibo Obs. Arecibo, Puerto RicoUNSPECIFIEDUNSPECIFIED
Rapp, MarkusDLR, IPAhttps://orcid.org/0000-0003-1508-5900UNSPECIFIED
Sulzer, Michael P.Arecibo Obs. Arecibo, Puerto RicoUNSPECIFIEDUNSPECIFIED
Verronen, Pekka T.University of Oulo, Sodankylä, FinlandUNSPECIFIEDUNSPECIFIED
Vierinen, JuhaUiT Arctoc Univ. of Norway, Tromso, NorwayUNSPECIFIEDUNSPECIFIED
Journal or Publication Title:Annales Geophysicae
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 519-530
Publisher:Copernicus Publications
Keywords:Terrestrial weather, Arecibo incoherent-scatter radar
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 - Middle Atmosphere
Location: Neustrelitz , Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics
Institute for Solar-Terrestrial Physics
Deposited By: Ziegele, Brigitte
Deposited On:09 Aug 2022 08:18
Last Modified:17 Aug 2022 13:55

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