Electric field measurements of DC and long wavelength structures associated with sporadic-<i>E</i> layers and QP radar echoes
Electric field and plasma density data gathered on a sounding rocket launched from Uchinoura Space Center, Japan, reveal a complex electrodynamics associated with sporadic-<i>E</i> layers and simultaneous observations of quasi-periodic radar echoes. The electrodynamics are characteri...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2005-10-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/23/2319/2005/angeo-23-2319-2005.pdf |
| _version_ | 1811274284400640000 |
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| author | R. Pfaff H. Freudenreich T. Yokoyama M. Yamamoto S. Fukao H. Mori S. Ohtsuki N. Iwagami |
| author_facet | R. Pfaff H. Freudenreich T. Yokoyama M. Yamamoto S. Fukao H. Mori S. Ohtsuki N. Iwagami |
| author_sort | R. Pfaff |
| collection | DOAJ |
| description | Electric field and plasma density data gathered on a sounding rocket
launched from Uchinoura Space Center, Japan, reveal a complex
electrodynamics associated with sporadic-<i>E</i> layers and simultaneous
observations of quasi-periodic radar echoes. The electrodynamics are
characterized by spatial and temporal variations that differed considerably
between the rocket's upleg and downleg traversals of the lower ionosphere.
Within the main sporadic-<i>E</i> layer (95–110 km) on the upleg, the electric
fields were variable, with amplitudes of 2–4 mV/m that changed considerably
within altitude intervals of 1–3 km. The identification of polarization
electric fields coinciding with plasma density enhancements and/or
depletions is not readily apparent. Within this region on the downleg,
however, the direction of the electric field revealed a marked change that
coincided precisely with the peak of a single, narrow sporadic-<i>E</i> plasma
density layer near 102.5 km. This shear was presumably associated with the
neutral wind shear responsible for the layer formation. The electric field
data above the sporadic-<i>E</i> layer on the upleg, from 110 km to the rocket
apogee of 152 km, revealed a continuous train of distinct, large scale,
quasi-periodic structures with wavelengths of 10–15 km and wavevectors
oriented between the NE-SW quadrants. The electric field structures had
typical amplitudes of 3–5 mV/m with one excursion to 9 mV/m, and in a very
general sense, were associated with perturbations in the plasma density. The
electric field waveforms showed evidence for steepening and/or convergence
effects and presumably had mapped upwards along the magnetic field from the
sporadic-<i>E</i> region below. Candidate mechanisms to explain the origin of these
structures include the Kelvin-Helmholtz instability and the <i>E<sub>s</sub></i>-layer
instability. In both cases, the same shear that formed the sporadic-<i>E</i> layer
would provide the energy to generate the km-scale structures. Other
possibilities include gravity waves or a combination of these processes.
The data suggest that these structures were associated with the lower
altitude density striations that were the seat of the QP radar echoes
observed simultaneously. They also appear to have been associated with the
mechanism responsible for a well-defined pattern of "whorls" in the
neutral wind data that were revealed in a chemical trail released by a
second sounding rocket launched 15min later. Short scale (<100 m)
electric field irregularities were also observed and were strongest in the
sporadic-<i>E</i> region below 110km. The irregularities were organized into 2–3
layers on the upleg, where the plasma density also displayed multiple
layers, yet were confined to a single layer on the downleg where the plasma
density showed a single, well-defined sporadic-<i>E</i> peak. The linear gradient
drift instability involving the DC electric field and the vertical plasma
gradient is shown to be incapable of driving the observed waves on the
upleg, but may have contributed to the growth of short scale waves on the
topside of the narrow unstable density gradient observed on the downleg. The
data suggest that other sources of free energy may have been important
factors for the growth of the short scale irregularities.<p>
<b>Keywords.</b> Ionosphere (Mid-latitude ionosphere; Electric
fields and currents; Ionospheric irregularities) |
| first_indexed | 2024-04-12T23:16:14Z |
| format | Article |
| id | doaj.art-81018c806a1f4087a46dc0cf4cd44721 |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-04-12T23:16:14Z |
| publishDate | 2005-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-81018c806a1f4087a46dc0cf4cd447212022-12-22T03:12:40ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762005-10-01232319233410.5194/angeo-23-2319-2005Electric field measurements of DC and long wavelength structures associated with sporadic-<i>E</i> layers and QP radar echoesR. Pfaff0H. Freudenreich1T. Yokoyama2M. Yamamoto3S. Fukao4H. Mori5S. Ohtsuki6N. Iwagami7NASA/Goddard Space Flight Center, Greenbelt, MD, USANASA/Goddard Space Flight Center, Greenbelt, MD, USAResearch Institute for Sustainable Humanosphere, Kyoto University, Kyoto, JapanResearch Institute for Sustainable Humanosphere, Kyoto University, Kyoto, JapanResearch Institute for Sustainable Humanosphere, Kyoto University, Kyoto, JapanNational Institute of Information and Communications, Tokyo, JapanDepartment of Earth and Planetary Science, University of Tokyo, Tokyo, JapanDepartment of Earth and Planetary Science, University of Tokyo, Tokyo, JapanElectric field and plasma density data gathered on a sounding rocket launched from Uchinoura Space Center, Japan, reveal a complex electrodynamics associated with sporadic-<i>E</i> layers and simultaneous observations of quasi-periodic radar echoes. The electrodynamics are characterized by spatial and temporal variations that differed considerably between the rocket's upleg and downleg traversals of the lower ionosphere. Within the main sporadic-<i>E</i> layer (95–110 km) on the upleg, the electric fields were variable, with amplitudes of 2–4 mV/m that changed considerably within altitude intervals of 1–3 km. The identification of polarization electric fields coinciding with plasma density enhancements and/or depletions is not readily apparent. Within this region on the downleg, however, the direction of the electric field revealed a marked change that coincided precisely with the peak of a single, narrow sporadic-<i>E</i> plasma density layer near 102.5 km. This shear was presumably associated with the neutral wind shear responsible for the layer formation. The electric field data above the sporadic-<i>E</i> layer on the upleg, from 110 km to the rocket apogee of 152 km, revealed a continuous train of distinct, large scale, quasi-periodic structures with wavelengths of 10–15 km and wavevectors oriented between the NE-SW quadrants. The electric field structures had typical amplitudes of 3–5 mV/m with one excursion to 9 mV/m, and in a very general sense, were associated with perturbations in the plasma density. The electric field waveforms showed evidence for steepening and/or convergence effects and presumably had mapped upwards along the magnetic field from the sporadic-<i>E</i> region below. Candidate mechanisms to explain the origin of these structures include the Kelvin-Helmholtz instability and the <i>E<sub>s</sub></i>-layer instability. In both cases, the same shear that formed the sporadic-<i>E</i> layer would provide the energy to generate the km-scale structures. Other possibilities include gravity waves or a combination of these processes. The data suggest that these structures were associated with the lower altitude density striations that were the seat of the QP radar echoes observed simultaneously. They also appear to have been associated with the mechanism responsible for a well-defined pattern of "whorls" in the neutral wind data that were revealed in a chemical trail released by a second sounding rocket launched 15min later. Short scale (<100 m) electric field irregularities were also observed and were strongest in the sporadic-<i>E</i> region below 110km. The irregularities were organized into 2–3 layers on the upleg, where the plasma density also displayed multiple layers, yet were confined to a single layer on the downleg where the plasma density showed a single, well-defined sporadic-<i>E</i> peak. The linear gradient drift instability involving the DC electric field and the vertical plasma gradient is shown to be incapable of driving the observed waves on the upleg, but may have contributed to the growth of short scale waves on the topside of the narrow unstable density gradient observed on the downleg. The data suggest that other sources of free energy may have been important factors for the growth of the short scale irregularities.<p> <b>Keywords.</b> Ionosphere (Mid-latitude ionosphere; Electric fields and currents; Ionospheric irregularities)https://www.ann-geophys.net/23/2319/2005/angeo-23-2319-2005.pdf |
| spellingShingle | R. Pfaff H. Freudenreich T. Yokoyama M. Yamamoto S. Fukao H. Mori S. Ohtsuki N. Iwagami Electric field measurements of DC and long wavelength structures associated with sporadic-<i>E</i> layers and QP radar echoes Annales Geophysicae |
| title | Electric field measurements of DC and long wavelength structures associated with sporadic-<i>E</i> layers and QP radar echoes |
| title_full | Electric field measurements of DC and long wavelength structures associated with sporadic-<i>E</i> layers and QP radar echoes |
| title_fullStr | Electric field measurements of DC and long wavelength structures associated with sporadic-<i>E</i> layers and QP radar echoes |
| title_full_unstemmed | Electric field measurements of DC and long wavelength structures associated with sporadic-<i>E</i> layers and QP radar echoes |
| title_short | Electric field measurements of DC and long wavelength structures associated with sporadic-<i>E</i> layers and QP radar echoes |
| title_sort | electric field measurements of dc and long wavelength structures associated with sporadic i e i layers and qp radar echoes |
| url | https://www.ann-geophys.net/23/2319/2005/angeo-23-2319-2005.pdf |
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