Images of transequatorial F region bubbles in 630- and 777-nm emissions compared with satellite measurements

Images of transequatorial F region bubbles were obtained from magnetic field aligned airglow observations from Haleakala, Hawaii, for 9 nights in August 1988. Bubbles of scale size 10–100 km were recorded with an intensified CCD detector attached to a filter wheel imager, and sequential images were...

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Veröffentlicht in:Journal of Geophysical Research 1997-02, Vol.102 (A2), p.2057-2077
Hauptverfasser: Tinsley, B. A., Rohrbaugh, R. P., Hanson, W. B., Broadfoot, A. L.
Format: Artikel
Sprache:eng
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Zusammenfassung:Images of transequatorial F region bubbles were obtained from magnetic field aligned airglow observations from Haleakala, Hawaii, for 9 nights in August 1988. Bubbles of scale size 10–100 km were recorded with an intensified CCD detector attached to a filter wheel imager, and sequential images were made in the plasma recombination emissions at 630 nm and 777 nm and in the background emissions. The observations also yield information on the large‐scale structure of the ionosphere in the northern Appleton Anomaly region, particularly on the latitude variations of plasma concentration and layer height. Measurements from the DMSP F8 and F9 satellites extend this to include the southern Anomaly region. The DMSP satellites were near 830 km in altitude and in near‐polar orbits at about 1800 and 2120 hours local time. A comparison of the bubble images and the DMSP results with plasma concentration and drift velocities obtained from the San Marco satellite allows us to put the measurements along the San Marco track into the larger ionospheric context. One‐to‐one correspondence is found between the presence of the optical bubbles and the presence of plasma depletions measured from the San Marco satellite, allowing identification on consecutive orbits of the same depletions. This extends for up to 5 hours of the satellite measured information for individual depletions, that is, their vertical and horizontal drift velocities and the plasma concentration variations. The images show the shapes of the depletions in apex height and longitude and their evolution. Horizontal drift velocities of the bubbles were determined by a correlation analysis. Bubble occurrence is compared with day‐to‐day changes in the equatorial fountain electric fields and transequatorial asymmetries caused by neutral winds, and with measurements of radar backscatter from centimeter‐scale irregularities associated with bubbles in the Kwajalein sector. The development of 10–100 km scale size bubbles at a given time and location is clearly a consequence of the presence of even larger wavelike corrugations in the F layer, provided there is also at least a moderately strong equatorial fountain.
ISSN:0148-0227
2156-2202
DOI:10.1029/95JA01398