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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 34, issue 5
Ann. Geophys., 34, 529-541, 2016
https://doi.org/10.5194/angeo-34-529-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 34, 529-541, 2016
https://doi.org/10.5194/angeo-34-529-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 10 May 2016

Regular paper | 10 May 2016

A multi-platform investigation of midlatitude sporadic E and its ties to EF coupling and meteor activity

Joseph Helmboldt Joseph Helmboldt
  • US Naval Research Laboratory, Code 7213, 4555 Overlook Ave. SW, Washington, DC 20375, USA

Abstract. This paper describes the results of a multi-platform observing campaign aimed at studying midlatitude sporadic E (Es) and associated ionospheric phenomena. The assets used were the digisonde in Boulder, Colorado; the first station of the Long Wavelength Array, LWA1, in New Mexico; the transmitters of the radio station WWV in Colorado; and 61 continuously operating GPS receivers between LWA1 and WWV. The results show that southwestward-directed medium-scale traveling ionospheric disturbances (MSTIDs) were substantially more prevalent when Es was detected. The amplitudes of these correlate with a plasma frequency up to about 4.5MHz. For fp5MHz, the MSTIDs become significantly weaker and basically vanish above  ∼6.5MHz. The prevalence of meteor trail reflections observed with LWA1 also correlates with fp up to about 4.5MHz; above this limit, the relationship exhibits a significant turnover. The observed intensity of coherent backscatter from Es field-aligned irregularities (FAIs) also correlates with inferred plasma frequency. However, this trend continues to higher frequencies with a peak near 6MHz, followed by a much more subtle turnover. The reflected power from Es structures observed with LWA1 is significantly more correlated on spatial scales between 10 and 40km. The magnitude of this correlation increases with fp up to  ∼  6MHz, above which it drops. These results are consistent with the following: (1) southwestward-directed MSTIDs are produced via EF coupling; (2) this coupling is stronger when the Es layer, seeded by meteor ablation, is more dense; (3) the coupling is substantially diminished for Es layers harboring extremely dense structures (fp5MHz).

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This paper details observed connections between dense, transient layers within the lower ionosphere (sporadic E) and both meteor activity and irregularities higher in the ionosphere. The coupling between these layers and wavelike disturbances in the middle ionosphere seems to be shorted out when extremely dense “clouds” are present, which possible disrupt the stability of the layers.
This paper details observed connections between dense, transient layers within the lower...
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