HR: 11:25h
AN: SA22A-05 INVITED     [Abstracts]
TI: Radar Observations of Midlatitude Irregularities at Low Latitudes
AU: * Tsunoda, R T
EM: tsunoda@sri.com
AF: SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025, United States
AB: There is a tendency to refer to plasma structures as "midlatitude," when found well poleward of the equatorial ionization anomaly (EIA), but equatorward of the subauroral region, and to attribute them to the Perkins instability. Similarly, there is a tendency to refer to plasma structures as "equatorial," when found equatorward of the EIA crest, and to attribute them to the Rayleigh-Taylor instability. There is evidence, however, that geomagnetic field lines, which thread equatorial plasma bubbles at very high altitudes, can pass through the peak of the F layer at magnetic dip latitudes poleward of the EIA. In these events, interpretation is in terms of equatorial structure penetrating into the midlatitude ionosphere. More recently, there has appeared evidence that midlatitude structures may be able to penetrate into the equatorial ionosphere, that is, to dip latitudes equatorward of the EIA crest. We present examples of the latter and discuss which of the processes may be acting to account for these observations.
DE: 2439 Ionospheric irregularities
DE: 2443 Midlatitude ionosphere
DE: 2471 Plasma waves and instabilities (2772)
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly