University of Oulu

M Macotela, E. L., Clilverd, M. A., Manninen, J., Thomson, N. R., Newnham, D. A., & Raita, T. ( 2019). The effect of ozone shadowing on the D region ionosphere during sunrise. Journal of Geophysical Research: Space Physics, 124, 3729– 3742.

The effect of ozone shadowing on the D region ionosphere during sunrise

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Author: Macotela, Edith L.1; Clilverd, Mark A.2; Manninen, Jyrki1;
Organizations: 1Sodankylä Geophysical Observatory, University of Oulu, Sodankylä, Finland
2Space Weather and Atmosphere, British Antarctic Survey (UKRI‐NERC), Cambridge, UK
3Department of Physics, University of Otago, Dunedin, New Zealand
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 16.3 MB)
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Language: English
Published: American Geophysical Union, 2019
Publish Date: 2019-10-25


Diurnal very low frequency subionospheric radio wave phase measurements show a night‐to‐day transition pattern. During this sunrise transition a phase perturbation, which consist of a phase overshoot followed by a small phase recovery to normal daytime values, is often observed. The variability of the size of this sunrise phase perturbation and its maximum and end times were monitored to identify the associated physical causes. Very low frequency signal from the 22.1‐kHz UK transmitter (call sign GVT) recorded at Sodankylä, Finland, from 20 April 2010 to 31 December 2016 were used. The timing at the maximum of the phase perturbation period has an annual pattern that is well described by the seasonal variation of the sunrise time 28 km above the transmitter. Variations in ozone number density at 38–42‐km altitudes are better correlated (R = 0.7) with the sunrise phase perturbation variability than at any other altitudes below ~80 km, and exhibit higher correlation values than for atmospheric temperature. Our results show that the main characteristics of the observed very low frequency sunrise phase perturbation arise from shadowing of short‐wavelength solar UV flux from the D region ionosphere due to stratospheric ozone absorption.

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Series: Journal of geophysical research. Space physics
ISSN: 2169-9380
ISSN-E: 2169-9402
ISSN-L: 2169-9380
Volume: 124
Issue: 5
Pages: 3729 - 3742
DOI: 10.1029/2018JA026415
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
114 Physical sciences
111 Mathematics
Funding: ELM was supported by the Suomen Kulttuurirahasto (grant 00180689) and the Oulun yliopiston tukisäätiö (grant 20180003). D.A.N. and M.A.C. were supported in part by the UK Natural Environment Research Council (grants NE/J022187/1 and NE/R016038/1).
Dataset Reference: Data availability is described at the following websites: (AARDDVARK) and (EOS MLS).
Copyright information: ©2019. American Geophysical Union. All Rights Reserved.