Weddell Sea and Yakutsk Anomalies in FOF2 from the Multipoint Observations
Abstract
Zone of the irregular variations in foF2 in the Northern and Southern hemispheres has been evolved from the ground-based data, Intercosmos-19 topside sounding data for the high solar activity, and CHAMP data for the low solar activity. In this zone in summer the night-time foF2 values exceed the day-time ones. Such behavior is known as Yakutsk anomaly in the Northern hemisphere and Weddell sea anomaly (WSA) in the Southern hemisphere. In the Southern hemisphere WSA covers all the longitudes of the western hemisphere 180-360° S and latitudes of 40-80° S, the maximum effect (up to 5 MHz) is observed at the longitudes of 255-315° and latitudes of 60-70° S (50-55° ILAT). In the Northern hemisphere anomaly is not so strong pronounced and occupies smaller area (at the latitudes of 55-65° N and the longitudes of 120-210° ). The main characteristics of the anomaly do not practically depend on the solar activity. The reasons of the anomaly formation on the basis of the quality and quantity analysis are examined. To accomplish this, the longitudinal variations in the ionospheric parameters for the midday and midnight conditions are in detail considered. They are mainly determined by the vertical drift effect induced by the neutral wind. The longitudinal variations in foF2 are strongly in the geomagnetic coordinates as a result of additional action of the solar radiation. The main ionospheric trough forms the poleward border of the anomaly. The other possible reasons are discussed.
- Publication:
-
38th COSPAR Scientific Assembly
- Pub Date:
- 2010
- Bibcode:
- 2010cosp...38..891K